University of California • Berkeley 1&&&&L t®p*g. ^tt&fW M r ^fc I *fmrt fPs£s1*f?L i PHILOSOPHICAL TRANSACTIONS OF THE -■ ROYAL SOCIETY OF LONDON, § FROM TH&IR COMMENCEMENT, IN 1665, TO THE YEAR 1800; 9flbrtoget»> WITH NOTES AND BIOGRAPHIC ILLUSTRATIONS, BY CHARLES HUTTON, LL.D. F.R.S. GEORGE SHAW, M.D. F.R.S. F.L.S. RICHARD PEARSON, M.D. F.S.A. VOL. XVIII. from 1796 to 1800. LONDON: PRINTED BY AND FOR C. AND R. BALDWIN, NEW BRIDGE-STREET, BLACKFRIARS. 1809. 6" t • * fVt>M\ LOAN STACK I CONTENTS OF VOLUME EIGHTEENTH. HPage EBERDEN, Wm., Jun. Effect of Cold on Health 1 Hatchett, on Carynthian Molybdate of Lead 4 Macdonald, Daily Variations of the Needle 29, 355 Outram, Singular Balls in a Tunnel 30 Gray, on an Earthquake in England .... 31 Sewell, the Binomial Theorem demonstrated 33 Home and Menzies, on the Sea Otter .... 34 Pearson, on Ancient Metallic Arms, &c. 38 Herschel, on the Periodical Star « Herculis; on the Rotation of Stars on their Axes, and the Comparative Brightness of the Stars 6l Barker, Meteorological Register 64, 300, 443, 580 Home, on" Blood extravas. in the Bladder 65 Correa de Serra, Fructification of the Sub- merged Algas 68 Home, Muscles and Cornea of the Eye . . 74 Huddart, on Horizontal Refractions .... 88 Mendoza, Problems of Nautical Astronomy 95 Cavendish, Correction of the observed Dis- tance of the Moon and a Star 9^ Tennant, on the Nature of the Diamond . . Q7 Marsham, on the Growth of Trees 100 Pigott, Edw. on two Periodical Stars .... 102 Pearson, on the Gaz produced from Water 104 Haighton, on Animal Impregnation 112 Cruikshank, on the same subject 129 Rumford, Donation for a Prize Medal. ... 137 R.S. Meteorological Journal 138, 315, 485, 666 Tennant, Action of Nitre and Gold, &c. . 138 Rumford, on the Force of Fired Gunpowder 140 Herschel, Third Catalogue of Stars 171 Vulliamy, on an Overflowing Well 184 Herschel, on Jupiter's Satellites 187 Brougham, on the Properties of Light. . . . 196 Wollaston, W. H. Gouty and Urinary Concretions 213 Henry, on Carbonated Hydrogenous Gas 221 Wells, Experiments on the Colour of Blood 228 Williams, Mudge, Dalby, Trigon. Survey 236 Vince, Resistance of Fluids to Bodies. . . . 248 Pearson, on Urinary Concretions 254 Herschel, Satellites of the Georgium Sidus 270 Rumford, on Heat excited by Friction . . 278 Abernethy, Foramen Thebesii of the Heart 287 Hatchett, of the Sydneia, or Terra Australis 290 Shuckburgh, Standard Weights and Mea. sures ...»,,.....,,.,... 300 VOL. XVIII. ; Page Hellins, of a Slowly Converging Series . . 312 Atwood, on the Stability of Ships 315 Prevost, Reflexibility of Light 320 Home, an Orifice in the Retina of the Eye 326 Wilson, Unusual Formation of the Heart 332 Latham, Wm., on Atmospherical Refrac- tions 337 Clark, a Tumour in the Human Placenta. . 338 Wood, on the Roots of Equations 341 Brougham, Theorems and Porisms in Geo- metry 345 Greville, on the Corundum Stone 356 Rumford, Chemical Properties of Light . . 378 Cavendish, on the Density of the Earth . . 388 Hellins, a Prob. in Physical Astronomy 408,599 Hatchett, Effects of the Mere of Diss 421 Wilkins, Catalogue of Sanscrita MSS. 427, ^63 Home, on the Structure of Nerves 430 Vince, unusual Horizontal Refractions . . 436 Home, on a Doubleheaded Child 443 Corse, Manners and Habits of the Elephant 444 Crell, on Acid of Borax, or Sedative Salt 457 Lax, the Latitude by two Altitudes and the Time 466 Herschel, a 4th Catalogue of the Stars .... 475 Correa de Serra, on a Submarine Forest . . 479 Home, Observations on Hermaphrodites. . 485 Rumford, (Count Rumford) on the Weight ascribed to Heat 496 Knight, on the Fecundation of Vegetables 504 Corse, Species and Dentition of Elephants 509 Home, on the Teeth of the Elephant, &c. 519 Biggin, on the Tanning Principle and Gal- lic Acid in Trees 527 Wilson, Resolution of Algebraic Equations 529 Tennant, on Lime for Agriculture 548 Hatchett, Observations on Shell and Bone 554 Home, on the Membrana Tympani of the Ear 566 Morgan, Contingent Reversions for 3 Lives 576 Herschel, Telescopic Penetration into Space 580 Carlisle, the Arteries of Slow moving Ani- mals 601 Young, Experiments on Sound and Light . 604 Cooper, the Membrana Tympani of the Ear 626 Home, on the same subject 630 Hulme, Spontaneous Light of Bodies .... ib Biographical Notice of Dr. Nat. Hulme . . ib Henry, Decomposing the Muriatic Acid . . 64 1 Howard, on a New Fulminating Mercury . 649 Wollaston, Wm. H. on Double Images by Atmospherical Refraction 667 n CONTENTS. Page Herschel, Heat and Light of Prismatic Rays 675 Herschel, Refrangibility of Invisible Rays 688 Herschel, Solar and Terrestrial Heat Rays 691, 750 Hatchett, on Zoophytes and on Membrane 706 Pa*e Volta, the Galvanic Pile or Electricity . . 744 Home, on the Ornithorhynchus Paradoxus 746 Mudge, Trigonometrical Survey of England 787 Edit. Davy's Electro. chemical Discoveries 79% THE CONTENTS CLASSED UNDER GENERAL HEADS. Class I. Mathematics. 1. Arithmetic, Annuities, Political Arithmetic. Contingent Reversion for 3 J Morgan 5?fi 2. Algebra, Analysis, Fluxions, Series. Binomial Theorem demon- ") ~ ,. „„ On the Roots of Equations, Wood 341 strated J ewe Resolution of Algebraic i ^yjjson 520 A Slowly Converging Series, Hellins 312 Equations j 3. Geometry, Trigonometry, Surveying. TEgnOIlandtriCal ^^ °' } Williams> &c- 236 ^Tland'™*1 ^^ °! } MudSe 7 S7 Geometrical Theorems and j Br ham 345 Ponsms J Class II. Mechanical Philosophy. 1. Dynamics. Resistance of Fluids Vince 248 The Density of the Earth . . Cavendish . . 388 A Prob. in Physical Astro- j HeUi nomy J ' 1. Statics. On the Stability of Ships . . Atwood 315 3. Astronomy, Chronology, Navigation. On the Periodical Star *"J Herculis; on the Rota- I tion of Stars on their >Herehel .... 6*1 Axes; and on the Bright- [ ness of the Stars J On Horizontal Refractions, Huddart 88 Problems of Nautical As- 1 Mendoza 05 tronomy J Correction of the observed ^ Distance of the Moon >Cavendish. ... 9$ Spa and a Star J Two Periodical Stars Pigott, Edw Third Catalogue of Stars . . Herschel . . On Jupiter's Satellites Herschel . . Satellites of the Georgium 1 Herschel Sidus J The Latitude by 2 Alti- 1 Lax tudes and the Time . . . . / Fourth Catalogue of Stars. . Herschel . . Telescopic Penetrat. int0 1 Herschel . . Space J The Force of Fired Gun. powder 4. Projectiles and Gunnery. Rumford 140 102 171 187 270 466 475 580 An Overflowing Well Vulliamy. CONTENTS. Page 5. Hydraulics. . . 184 6. Pneumatics. Page The Force of Fired Gun- powder Rumford . 140 On Horizontal Refractions. . Huddart .... 88 The Properties of Light . . Brougham . . 196 Reflexibility of Light .... Prevost .... 320 Atmospherical Refractions . . Latham, Wm. 337 Chemical Properties of Light, Rumford .... 378 Horizontal Refractions .... Vince 436 Telescopic Penetrat. into 1 He„chel Space ■ Experiments on Sound and Light 7. Optics. Spontaneous Light of Bodies, Hulme 6*30 Double Images by Atmos- J Wollagton>w.H.66y pher Heat and Light of Prisma, tic Rays i Herschel 675 Refrangibility of Refran- J Herschel # _ 6gs J* Herschel 580 Fhle Rays J i Solar and TerrestrialHeat- 1 Herschel 6o2 750 JYoung 604 Ra?s S 8. Electricity, Magnetism, Thermometry. D iNenedleVariati0n f 9? } Mcdonald, 29, 3 55 ° jgj* Weight aSCribed t0 } Rumford .... 496 Donation for a Prize Medal, Rumford .... 137 GalvanicPiIe,or Electricity, Volta 744 The Heat excited by Fric- 1 j>r. 2_8 Davy's Experiments with I •& « . 7Q8 tion / the same J '■* Class III. Natural History. 1. Zoology. On the Sea-Otter Home and Menzies 34 1. Mineralogy, CLeaahian M61ybdatG °f}Hatchett .... 4 Singular Balls in a Tunnel, Outram . The Nature of the Diamond, Tennant . The Sydneia, or Terra Au- J Hatchett 30 97 On the Ornithorhyncus )„ 6 Paradoxus J Fossilogy, &c. On the Corundum Stone. .. . Greville .... 356 On a Submarine Forest . . Correa de Serra 479 On Zoophytes, and on 7 Membrane j Hatchett 706 stralis 3 290 3. Geography. On the Density of the Earth, Cavendish.. 388 Class IV. Chemical Philosophy. ] . Chemistry. Carynthian Molybdate of7 Hatchett Lead } The Gaz produced from } p Water ) Actionof Nitre on Gold, &c. Tennant CarbonatedHydrogenousGas, Henry. . Effects of the Mi re of Diss, Hatchett Acid of Borax, or Sedative i rjrell Salt j 104 138 221 421 457 On the Tanning Principle 1 and Gallic Acid in Trees J On Lime for Agriculture . . Observations on Shell and ) Bone J The Spontaneous Light of I Bodies j Decomposing the Muriatic \ Acid j A NewFulminatingMercury, Biggin . Tennant Hatchett Hulme . . Henry . . Howard .. 527 . 548 . 554 . 630 . 641 . 649 IV CONTENTS. Page Page 2. Meteorology. Meteorological Register. . . . Barker. . 64, 300, Meteorological Journal R.S. 138, 315, 485, 442, 580 0fo 3. Geology, An Earthquake in England, Gray 31 Class V. Physiology. 1. Anatomy. Cornea and Muscles of the \ ■»„_. ~, On the Structure of the") 1T Eyes JH°me 74 Nerves j Home i *™ Foramen Thebesii of the \ ADernethy 287 ^n a Douhle-neaaed Child, Home 443 Heart / * ' Observations on Herma- 7 „__ An Orifice in the Retina of \ jjome 32g phrodites 5 the Eye / The Membrana Tympani 7 „ Unusual Formation of the ? m^ „o9 of the Ear J rt Lome 485 > Home . . 566, 630 Heart J " """" *** On the same subject Cooper 626 2. Physiology of Animls. On Animal Impregnation . . Haighton 112 Manners and Habits of the 7 r On the same subject Cruikshank. . 129 Elephant \ Uorse 44?* Gouty and Urinary Con.") Wo11wh2]3 Species and Dentition of J c cretions J Elephants J jyjJ Expers. on the Colour oflw,lo ona On the Teeth of the Ele- "» „ i.„ theBlood JWellS 228 phant,&c JHome 519 On Urinary Concretions ..Pearson 254 Arteries of Slow-moving 7 n ,. . ,. On a Double-headed Child, Home 443 Animals \ Carhsle • • • • ©01 3. Physiology of Plants. Fre"yfthe.SUb:}CO"eadeSC"168 0geUbtCUndat.i0nOf.Ve;}KniSht .... 50* On the Growth of Trees Marsham 100 4. Medicine and Surgery. Effect of Cold on Health . . W. Heberden 1 Tumour in the Human Pla- \r. . On Blood extravas. in the 1 jjome gc centa / ^lark 338 Bladder J Class VI. The Arts. 1. Mechanical Arts. *mSLJ?*?. .and. } Shuckbur«h- • 300 2. Antiquities. Ancient Metallic Arms, &c. Pearson 38 On a Submarine Forest .... Cor. de Serra 479 Catalogue of Sanscrit MSS. Wilkins 427, 563 Class VII. Biography. Biographical Notice of Dr. Nat. Hulme . . 630 THE PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY OF LONDON; ABRIDGED. XI. Of the Influence of Cold on the Health of the Inhabitants of London. By Wm. Heberden, Jun., M. D., F. R. S. p. 279. The extraordinary mildness of last Jan. (179@) compared with the unusual seve- rity of the Jan. preceding, affords a peculiarly favourable opportunity of observing the effect of each of these seasons contrasted with each other. For of these 2 successive winters, one has been the coldest, and the other the warmest, of which any regular account has ever been kept in this country. Nor is this by any means an idle speculation, or matter of mere curiosity; for one of the first steps towards preserving the health of our fellow-creatures, is to point out the sources from which diseases are to be apprehended. And what may make the present inquiry more par- ticularly useful, is that the result, as I hope clearly to make appear by the fol- lowing statements, is entirely contrary to the prejudices usually entertained on this subject. During last Jan. nothing was more common than to hear expressions of the unseasonableness of the weather; and fears lest the want of the usual degree of cold, should be productive of putrid diseases, and I know not what other causes of mortality. On the other hand, " a bracing cold," and " a clear frost," are fa- miliar in the mouth of every Englishman ; and what he is taught to wish for, as among the greatest promoters of health and vigour. Whatever deference be due to received opinions, it appears to me however from the strongest evidence, that the prejudices of the world are on this point at least unfounded. The average degrees of heat on Fahrenheit's thermometer kept in London during the month of Jan. 1795, was 23° in the morning, and 29°.4 in the afternoon. The average in Jan. 1796, was 43°.5 in the morning, and 50°. 1 in the afternoon. A difference of above 20 degrees ! And if we turn our attention from the comparative coldness of these months, to the corresponding healthiness of each, collected from the weekly bills of mortality, we shall find the result no less remarkable. For in 5 weeks between the 31st of Dec. 1794 and the 3d of Feb. 1795, the whole number of burials amounted to 2823 ; and in an equal period of 5 weeks between the 30th of Dec. 1/95 and the 2d of Feb. 1796, to 147 1. So VOL. xviii. B 2 PHILOSOPHICAL TRANSACTIONS. [ANNO 17 Q6. that the excess of the mortality in Jan. 1795 above that of Jan. 1796, was not less than of 1352 persons. A number sufficient surely to awaken the attention of the most prejudiced admirers of a frosty winter. And though I have only stated the evi- dence of 2 years, the same conclusion may universally be drawn; as I have learned from a careful examination of the weekly bills of mortality for many years. These 2 seasons were chosen as being each of them very remarkable, and in immediate succession one to the other, and in every body's recollection. It may not be impertinent to the objects of this Society, without entering too much into the province of medicine, to consider a little more particularly the several ways in which this effect may be supposed to be produced; and to point out some of the principal injuries which people are liable to sustain in their health from a severe frost. And one of the first things that must strike every mind engaged in this investigation, is its effect on old people. It is curious to observe among those who are said in the bills to die above 60 years of age, how regularly the tide of mortality follows the influence of this prevailing cause: so that a person used to such inquiries, may form no contemptible judgment of the severity of any of our winter months, merely by attending to this circumstance. Thus their number last Jan. was not much above ± of what it had been in the same month the year be- fore. The article of asthma, as might be expected, is prodigiously increased, and perhaps includes no inconsiderable part of the mortality of the aged. After these come apoplexies and palsies, fevers, consumptions, and dropsies. Under the 2 last of which are contained a large proportion of the chronical diseases of this country ; all which seem to be hurried on to a premature termination. The whole will most readily be seen at one view in the following table. Week ending. Mean heat. Whole N° of deaths. Aged above 60. Asthma. Apoplexy; and palsy. Fever. Consump- tion. Dropsy. Morn. Noon. r 6 Jan. 25° 29° 244 51 13 4 20 73 7 13 Jan. 26 32 532 139 26 13 49 158 20 20 Jan. 24 30 637 145 51 11 81 164 37 1795. < 27 Jan. 19 27 543 143 64 11 42 157 17 3 Feb. 25 37 867 239 95 13 66 273 45 Result 23 29 .4 2823 717 249 52 258 825 126 5 Jan. 40° 46' 300 35 5 7 34 79 13 12 Jan. 41 49 273 37 9 5 25 53 19 19 Jan. 48 53 313 29 2 4 29 77 11 1706. < 26* Jan. 47 52 257 20 7 9 23 47 11 7 3 Feb. 41 49 328 32 6 6 23 86 16 [■ Result 43 .5 50 .1 1471 153 29 31 134 342 70 Notwithstanding the plague, the remittent fever, the dysentery, and the scurvy, have so decreased, that their very name is almost unknown in London ; yet there VOL. LXXXVI.] PHILOSOPHICAL TRANSACTIONS. 3 has, I know not how, arisen a prejudice concerning putrid diseases, which seems to have made people more and more apprehensive of them, as the danger has been getting less. It must in great measure be attributed to this, that the consumption of Peruvian bark in this country has, within the last 50 years, increased from 14,000 to above 100,000 lb. annually. And the same cause has probably contributed, from a mistaken mode of reasoning, to prepossess people with the idea of the wholesomeness of a hard frost. But it has in another place * been very ably de- monstrated, that a long frost is eventually productive of the worst putrid fevers that are at this time known in London ; and that heat does in fact, prove a real pre- ventive against that disease. And though this may be said to be a very remote effect of the cold, it is not therefore the less real in its influence on the mortality of London. Accordingly a comparison of the numbers in the foregoing table will show that very nearly twice as many persons died of fevers in Jan. 17Q5, as did in the corresponding month of this year. I might go on to observe that the true scurvy was last year generated in the metropolis from the same causes extended to an unusual length. But these are by no means the only ways, nor indeed do they seem to be the principal ways, in which a frost operates to the destruction of great numbers of people. The poor, as they are worse protected from the wea- ther, so are they of course the greatest sufferers by its inclemency. But every physician in London, and every apothecary, can add his testimony, that their busi- ness among all ranks of people never fails to increase, and to decrease, with the frost. For if there be any whose lungs are tender, any whose constitution has been impaired either by age, or by intemperance, or by disease; he will be very liable to have all his complaints increased, and all his infirmities aggravated by such a season. Nor must the young and active think themselves quite secure, or fancy their health will be confirmed by imprudently exposing themselves. The stoutest man may meet with impediments to his recovery from accidents otherwise incon- siderable; or may contract inflammations, or coughs, and lay the foundation of the severest ills. In a country where the prevailing complaints among all orders of people are colds, coughs, consumptions, and rheumatisms, no prudent man can surely suppose that unnecessary exposure to an inclement sky; that priding one-self on going without any additional clothing in the severest winter; that inuring one- self to be hardy, at a time that demands our cherishing the firmest constitution lest it suffer; that braving the winds, and challenging the rudest efforts of the season, can ever be generally useful to Englishmen. But if generally, and on the whole, it be inexpedient, then ought every one for himself to take care that he be not the sufferer. For many doctrines very importantly erroneous; many remedies either vain, or even noxious, are daily imposed on the world for want of attention to this great truth ; that it is from general effects only, and those founded on ex- tensive experience, that any maxim, to which each individual may with confidence defer, can possibly be established. * Observations on the Jail Fever, by Dr. Hunter, Med. Trans, vol. 3. — Orig, B 1 4 PHILOSOPHICAL TRANSACTIONS. [ANNO 17 Q6. XII. An Analysis of the Carynthian Molybdate of Lead ; with Experiments on the Molybdic Acid. To which are added some Experiments and Observations on the Decomposition of the Sulphate of Ammonia. By Charles Hatchett, Esq. p. 285. § 1. The celebrated Scheele, in 1778, read before the Acad, of Sc. at Stockholm an essay, in which he proved, by a series of experiments, that the mineral called Molybdaena was composed of sulphur, and a peculiar metallic substance, which, like arsenic and tungsten, was liable by super-oxygenation to be converted into a me- tallic acid, which in its properties differed from every other that had been previously discovered *. The experiments of M. Pelletier-j~, Mr. Islmann;};, and Mr. Hielm §, confirmed the discovery of the Swedish chemist ; but the existence of this metallic substance was only known to be in that mineral which Scheele had examined, as no vestige of it had as yet been discovered in other bodies appertaining to the mi- neral kingdom. Mr. Jacquin, in 1781 and 1786, gave to the public an account, from the Abbe Wulfen, of a yellow sparry lead ore, found at Villach in Carinthia||; and the Abbe Wulfen himself, in an elaborate work, written in the German lan- guage, and published in 1785, also described the above-mentioned lead ore, toge- ther with some experiments which had been made on it ^[. Nothing satisfactory however relative to its nature was exposed in these memoirs ; and though the sub- stance was indisputably proved to be an ore of lead, yet the mineralizing principle of it remained unknown. In 1790, Mr. Heyer, of Brunswick, made some experiments on this ore; from which he inferred that it was composed of lead, combined with the tungstic acid**; and in the same year Mr. Klaproth communicated a similar account, which he had received from Mr. Salzwedel, of Frankfort sur Mayne -\"\-. This substance was therefore universally believed to be a tungstate of lead, till that excellent chemist Mr. Klaproth undertook to subject it to a further examination ; and as the experi- ments which I have made may be regarded as a continuation of those made by Mr. Klaproth, I think it necessary here to mention them. Mr. Klaproth says, that by previous experiments he had found, that nitric acid much diluted did not attack the ore when cold ; and therefore to separate it from the soluble matrix, he successively poured small quantities of the diluted acid on the ore till all effervescence had ceased, after which the ore was washed and dried. The nitric acid which had been employed was found to contain calcareous earth, and also a considerable quantity of red oxyde of iron, which on being dissolved in * Scheele's Essays, transl. by Dr. Beddoes, p. 227.. f Journ. de Phys. Dec. 1785. \ Chem. Ann. von Crell, 1787, et Journ. de Phys. Oct. 1788. § Journ. de Phys. Mai, 1789. ' || Nic Jos. Jacquin Misc. Austr. torn. 2, p. 139 i et N. J. Jacquin Collect, torn. 1, p. 3. This ore is also described in Lithophyl. Bornianum, torn. 1, p. 90; et torn 2, p. 123. — Karsten in Mus. Lesk. torn. 2, p. 501. — Werner's Verziech. Band, 1, p. 128. — Raab's Catal. tome 2, p. 379. — Rome de l'lsle Cristal. tome 3, p. 387. — Widenmann's Handb. der Mineralogie, p. 864. ^f Xavier Wulfens Abhand. vom Karnthnerischen Bleyspate. Wien, 1785. ** Chem. Ann. von Crell, 1790, p. 58. ft lbLd- l79°> P- 297.— Orig. VOL. LXXXVI.] PHILOSOPHICAL TRANSACTIONS. 5 sulphuric acid, left a residuum of lead and siliceous earth *. Two drs. of the purified ore were mixed with an equal quantity of pot-ash, and afterwards exposed to the fire in a crucible. The mixture melted without intumescence. When cold, the mass was of a reddish colour, and the surface was covered with small scales. Water was poured on it, and the solution was saturated with nitric acid. The next day, the bottom of the glass was found covered with projecting crystals, about -£• of an inch in length : these crystals were formed of small glittering rhomboi- dal plates, heaped one on the other. Their flavour was rather metallic. They quickly melted with the blow-pipe, on charcoal, without any increase of bulk, and became small* round drops, which were immediately absorbed by the charcoal. When melted by the blow-pipe in a silver spoon, ,the,y appeared as small grains, of a greyish colour, which became streaked in cooling, and deposited a white pow- der during the operation. When the phosphate of ammonia and soda was melted, and some of these crystals were added, they speedily dissolved, and communicated to the salt a green colour, more or less deep according to the quantity employed. They completely dissolved in distilled water, when heated. Prussiate of pot-ash with this solution produced a reddish-brown precipitate, not very dark. When some drops of muri- atic acid were mixed with the solution of these crystals in water, and a small piece of tin was added, the liquor became of a deep blue. The solution of muriat of tin poured on the crystals produced the same effect. Mr. Klaproth from these experiments concludes, that the crystals are the aci- dulous molybdate of pot-ash, especially as the crystals obtained from the filtrated solution of the molybdaena of Altenberg, detonated with nitre, and saturated with nitric acid, have the same properties. As in the above experiment the ore did not appear to have been completely decomposed, Mr. Klaproth mixed 2 drs. of the purified ore with 10 of carbonate of pot-ash, melted the whole in a crucible, and reduced it to powder, and dissolved it in water. The solution was filtrated, par- tially saturated with muriatic acid, and heated. A white precipitate fell, resembling curdled milk, which consisted of molybdic acid, and a still larger quantity of oxyde of lead. When dissolved in muriatic acid, the lead was precipitated in the state of muriate of lead. This precipitate being separated by a filter from the alkaline solution partially saturated with muriatic acid, the solution was then com- pletely saturated with the same acid, and again became slightly turbid, and depo- sited a white precipitate, which resembled starch in cold water. This precipitate, after it had been washed and dried, was subjected to the same experiments as the above-mentioned crystals, and exhibited the same properties, excepting that it did not dissolve in distilled water till some drops of muriatic acid were added. When the solution was evaporated in a glass basin, the rest of the oxyde of molybdaena was deposited in the form of a heavy citron-coloured powder. The white oxyde of lead on the filter through which the solution of the alkaline mass * Analyse Chimique du Plomb Spathique jaune de Carinthie An. de Chiraie, 1751, p. 103.— Orig. 6 PHILOSOPHICAL TRANSACTIONS. [ANNO 17Q0. had passed, was found to be mixed with siliceous earth. When melted on charcoal, it did not entirely assume the metallic form, but a part changed into a small grain of transparent yellowish vitrified oxyde of lead. Mr. Klaproth observes, that in this experiment the presence of the siliceous earth prevented the complete reduction of the lead, in the same manner as when glass of lead, composed of 3 parts of oxyde of lead and 1 of siliceous earth, is melted on charcoal. He therefore dissolved this oxyde in weak nitric acid, separated the siliceous earth by a filter, and precipi- tated the lead by sulphuric acid. Mr. Klaproth however, doubts whether the greater part of the siliceous earth was not introduced, during the operation, by the action of the alkali on the crucible. A drachm of the ore was digested with a considerable quantity of nitric acid, and a great part was dissolved. In the solution white flocculi were perceived, and were separated by a filter. When dried they were like a membrane, which became bluish when exposed to the light, and much resembled the molybdic acid obtained from molybdaena, by repeatedly distilling nitric acid from it. In the filtrated nitric solution there was much oxyde of molybdaena mixed with oxyde of lead. The lead was therefore precipitated by sulphuric acid, and afterwards the molybdaena by prussiate of pot-ash. A drachm of the ore was digested with muriatic acid; and was completely dis- solved, excepting a small residuum of siliceous earth. The solution was transpa- rent, and without colour. In the course of some time it plentifully deposited crys- tals of muriated lead. When these crystals were separated, the solution was evapo- rated, and the interior of the basin was, during the evaporation, covered with a bluish saline crust, which dissolved and the colour disappeared when the vessel was shaken. The concentrated solution decanted from the muriate of lead, which had been precipitated during the evaporation, was of a deep blue, which disappeared when water was added. The solution was then saturated with alkali, and deposited a white precipitate, which consisted of molybdic acid, together with a small quan- tity of oxyde of lead. According to these experiments Mr. Klaproth remarks, that the yellow sparry lead ore of Carinthia is composed of oxyde of lead and molybdic acid, and that this mineralogical novelty is the more remarkable, as it is the only one of the kind known at present. It is also worthy of notice, that the molybdaena changes its form according to the method employed to precipitate it from alkaline solutions ; for it is obtained either in a crystalline form, or in that of a white powder, or in that of citron-coloured oxyde. When crystallized, it is soluble in acids, and in water; as a white powder it does not dissolve in water, unless a small quantity of muriatic acid be added ; but in the state of the citron-coloured oxyde, it is insoluble in wa- ter as well as in the acids. Mr. Klaproth considers that this difference is occa- sioned by the presence of some alkali in the first 2 substances, so as to form an imperfect neutral salt with the molybdic acid, but that the yellow powder is in the state of a simple oxyde. This yellow colour probably occasioned the suppo- VOL. LXXXVI.] PHILOSOPHICAL TRANSACTIONS. 7 sition that the lead was mineralized by the tungstic acid ; but the blow-pipe is suffi- cient to distinguish them. The yellow oxyde of molybdaena loses the colour as soon as the point of the flame touches it, inclines to an olive colour, and melts into small grains, which are immediately absorbed by the charcoal. In the phosphate of ammonia and soda it dissolves, and communicates to it a green colour. On the contrary, the yellow oxyde of tungsten by ignition becomes blue or black, remain- ing refractory, and with phosphate of ammonia and soda it produces a sky-blue glass. Mr. Klaproth concludes his paper by saying, that he could not exactly determine the proportions of the ingredients, as the quantity of the ore in his possession was not sufficient to make the necessary allowance for the solubility of the oxyde of lead in the alkalis, and especially that of the molybdic acid when in a state of combination. These experiments of Mr. Klaproth, certainly prove that this ore is a molybdate of lead ; but as the quantity which he had was too small, either to make a greater number of experiments, or a regular analysis, I was induced to attempt a further investigation of it ; and therefore in the course of the last summer I made the experiments and analysis which are described in this paper. § 1. Characters of the Carinthian Molybdate of Lead. — The molybdate of lead is found at Villach, in Carinthia *. The matrix is a lime-stone, of a pale brown- ish-grey colour, often more or less tinged with oxyde of iron. The ore is a heavy brittle substance, easily scratched with a knife, and of a yellow colour, varying from pale yellow to orange. The fracture is sparry. The external lustre is like that of wax ; and when crystallized, 2 of the faces of the crystals are commonly opaque, and of a pale yellow, but the remaining 4 faces or sides have a resinous appearance. It generally exhibits an appearance of crystal- lization, and the crystals, when perfect, afford various modifications between the octoedral figure and the cube. The specific gravity of a specimen, from which I had separated all the visible part of the matrix, was 5092, the temperature of the water being 60°, but when the ore was reduced to powder, and purified by diluted nitric acid, I found the spe- cific gravity to be 5706. 1. When the ore was examined by the blow-pipe, it at first split and crackled as soon as the point of the flame touched it, but afterwards readily melted into a dark-coloured mass, in which were some shining globules of lead. 1. With borax it formed a brownish-yellow globule ; but when it was in a small proportion, and heated by the interior flame, it occasionally produced a glass, which was greenish blue, and sometimes deep blue. 3. With phosphate of ammonia and soda it formed a sea-green glass, which in proportion to the quantity of the ore sometimes became deeper in colour, so as to be nearly of a deep blue. Before making the following experiments, I reduced 8 oz. of the ore to a fine powder, and dissolved the matrix after the manner of Klaproth, by successively * It is said to have been sometimes found in Austria and Hungary, but I doubt if the nature of these ores is the same.— Orig. I PHILOSOPHICAL TRANSACTIONS. [ANNO 17q6. pouring on the powder small quantities of nitric acid diluted with 6 parts of distilled water, after which I edulcorated and dried the residuum. The nitric acid used in this operation contained, as Klaproth has mentioned, calcareous earth, oxyde of iron, and oxyde of lead ; but as prussiate of pot-ash produced a pale green preci- pitate, I suspected that some other metallic substance beside iron and lead was in the solution. I therefore added muriate of tin to a portion of it, which was imme- diately changed from a pale yellow to -a pale blue, and showed that a small quan- tity of molybdic acid was present in the solution. § 3. Molybdate of lead mith water. — I boiled 12 oz. of distilled water on 20 grs. of the purified ore in a glass matrass during 3 hours. The ore did not appear to be changed, nor did the water after it had passed the filter afford any trace of matter in solution. I believe therefore that the molybdate of lead is in- soluble in water. §4. As Mr. Klaproth had proved the action of the fixed alkalies on the mo- lybdate of lead, in the dry way, I was desirous to know what effects they would produce in the humid way, and therefore made the following experiments. Exper. 1. a. I boiled 4 oz. of strong lixivium of caustic pot-ash with 20 grs. of the purified ore, till there remained at the bottom of the matrass a dry mass, which was partly red, yellow, and green. I reduced this to powder, and poured distilled water on it, till the water came away without any taste. The alkaline solution was nitrated, and afterwards saturated with sulphuric acid. The liquor then became turbid, and deposited a small quantity, of a white precipitate, which consisted of lead and some molybdic acid. This was separated by a filter, and prussiate of pot-ash being added to the clear liquor, precipitated a great quantity of molybdaena, in the state of a reddish-brown flocculent precipitate. b. I took the residuum of the alkaline solution, which now was chiefly of a red colour, and appeared like. minium, and poured nitric acid very largely diluted on it, till the whole was dissolved. I then precipitated the lead with sulphuric acid, and from the clear liquor which remained, I afterwards, by the means of prussiate of pot-ash, obtained a quantity of Prussian blue. Exber. 2. a. 20 grs. of the purified ore were boiled with 4 oz. of a lixivium of carbonate of pot-ash. When all the water was evaporated, there remained a white saline mass, which was reduced to powder, and treated with distilled water as in the former experiment. A large quantity of a heavy white residuum remained on the filter. The clear solution was saturated as before with sulphuric acid, and a white precipitate, similar to that of the former experiment, was obtained. This was se- parated, and a copious precipitate of molybdaena was produced, on the addition of prussiate of pot-ash. b. The white residuum was then edulcorated, and when diluted nitric acid was poured on it, it was dissolved with effervescence. From this solution I precipitated the lead by sulphuric acid, and afterwards the iron by prussiate of pot-ash. Am- monia, when digested on the ore, had not any effect. From these experiments VOL. LXXXVI.] PHILOSOPHICAL TRANSACTIONS. g it appears, that the molybdate of lead is decomposed by the fixed alkalies in the humid way, and that the component parts of the ore are lead and iron mineralized by the molybdic acid *. § 5. Molybdate of lead with sulphur. — A mixture, composed of 50 grs. of the ore and 150 grs. of sulphur, was put into a small glass retorts, to which a receiver was luted. The fire was then gradually raised till all the sulphur was driven over, and the bottom of the retort began to melt. The residuum was a black, loose pow- der, which was greasy to the touch, and soiled the fingers like molybdaena. This black powder was digested in a strong heat with nitric acid, diluted with 3 parts of water. Nitrous fumes were discharged during the digestion, and the powder was dissolved, excepting a residuum of molybdic acid, which was of a greenish-yellow colour. The solution was diluted with an equal quantity of distilled water, and was filtrated. Sulphuric acid was then added till all the lead was precipitated ; after which I obtained a brown precipitate by prussiate of pot-ash -j~. ^ 6. Molybdate of lead with carbonate of ammonia. — A mixture, composed of 50 grs. of the ore and 220 grs. of dry carbonate of ammonia, was put into a glass retort, and was sublimed with a gentle heat. The molybdate of lead remained in the retort without having suffered any apparent alteration. The ammonia however had raised a small portion ; for when it was dissolved in distilled water, and was saturated with an acid, prussiate of pot-ash produced a brown cloud. § 7. Molybdate of lead sublimed with muriate of ammonia. — Exper. 1. A mixture of 50 grs. of the molybdate of lead and 240 grs. of muriate of ammonia was sublimed. The sublimate was partly yellow, green, and blue ; there was also some muriatic acid, and the residuum was a black powder ^. a. The sublimate was mixed with an equal weight of sulphur and distilled. The residuum of this was a black powder, resembling the mineral called molybdaena, and when distilled with nitric acid, afforded a citron-coloured oxyde. b. A quantity of distilled water was boiled on the residuum of the first sublima- tion, by which a part was dissolved, and communicated a blue colour to the water. 1. Prussiate of pot-ash added to some of this blue liquor, produced a precipitate of Prussian blue. 2. Sulphuric acid added to another portion deepened the blue colour. 3. Lixivium of carbonate of soda precipitated some ochry matter. 4. And nitrate of silver was decomposed, and muriate of silver was precipitated. c. Nitric acid diluted with 6 parts of water was then poured on the undissolved powder, and was digested on it in a sand-heat. The powder was nearly dissolved, * The alkalies, whether caustic or combined with carbonic acid, do not act in the humid way on mo- lybdaena when mineralized by sulphur. Scheele's Essays, p. 230 ; and Mem. sur la Molybdene, par M. Pelletier, Journal de Phys. Dec. 1785, p. 437. — Orig. + As the quantity of molybdic acid in the ore is much greater than that of iron, it is scarcely possible to discover the latter when they are precipitated together by prussiate of pot-ash. — Orig. + M. Sage has observed, that molybdaena with muriate of ammonia affords a blue sublimate. Journ. de Phys. 1788, p. 389.— Orig. VOL. XVIII. C 10 PHILOSOPHICAL TRANSACTIONS. [ANNO \7Q6. and the solution was colourless. 1 . From this solution I precipitated sulphate of lead by the means of sulphuric acid. 2. With prussiate of pot-ash I obtained a brown precipitate of molybdaena ; and 3. Muriate of tin turned another portion of it blue. From these experiments it appears that the 1st solution contained iron, with some molybdic acid dissolved in muriatic acid ; and the 2d solution contained molybdic acid and lead. Molybdate of lead sublimed with muriate of ammonia. — Exper. 1. 125 grs. of the ore were mixed with 2 oz. of muriate of ammonia, and put into an earthen matrass, to which a head of stone-ware was fitted. The matrass was then exposed to a sufficient degree of heat, and when all was sublimed the vessels were separated. The black powder which remained was mixed with 2 oz. of muriate of ammonia, and again sublimed. This operation was repeated 3 times, after which nothing re- mained in the matrass. The sublimate, as before, was yellow, green, and blue. a. Distilled water was poured on the sublimate, so as to dissolve all of the saline part ; but as the solution was turbid, it was poured on a filter, which collected a precipitate of a pale bluish-grey colour. . b. This precipitate after it had been edulcorated was boiled with distilled water, which was afterwards filtrated. 1. Prussiate of pot-ash precipitated some iron. 2. Muriatic acid was added to another portion, after which the prussiate produced a brown precipitate of molybdaena. 3. Muriate of silver was precipitated when nitrate of silver was dropped in. c. I then boiled lixivium of carbonate of pot-ash on the undissolved part of the residuum, by which the greatest part was dissolved. The alkali was then satu- rated with muriatic acid, and prussiate of pot-ash being added, precipitated some molybdaena. On the small portion of the residuum which remained I poured diluted nitric acid. The solution was then filtrated, and I obtained a small quan- tity of sulphate of lead by the means of sulphuric acid. These experiments show that the residuum was composed of molybdic acid, iron, lead, and a small quan- tity of muriatic acid, which was produced from the muriate of ammonia during the sublimation. d. I now took the solution a and divided it into 2 portions, to 1 of which I added 3 oz. of concentrated sulphuric acid, and evaporated the liquor to half the quantity. When cold it deposited a white saline matter, which for the greater part dissolved in water, leaving a small residuum which appeared to be muriate of lead. Pot-ash expelled some ammonia from a portion of the dry salt ; and a pre- cipitate was produced when muriate of barytes was added to the solution. This white saline matter was therefore a mixture of sulphate of ammonia with a small portion of muriate of lead. The solution to which the sulphuric acid had been added was again evaporated to a considerable degree, and when cold it resembled a very thick mucilage of a pale yellow colour. It readily dissolved in water, and contained sulphuric acid in great VOL. LXXXVI.] PHILOSOPHICAL TRANSACTIONS. ] 1 excess. 1. Prussiate of pot-ash only changed the colour to pale green. 2. Car- bonate of pot-ash expelled the ammonia, and a white precipitate like starch was formed, which was principally composed of molybdic acid and pot-ash. e. To the 2d portion of the solution I added 3 oz. of concentrated nitric acid, and evaporated it nearly to dryness. A bright yellow matter was deposited, which I found to be molybdic acid combined with a portion of lead. There was also a small quantity of liquid, which I diluted with distilled water, and then precipitated some sulphate of lead by sulphuric acid. When this was separated I added prus- siate of pot-ash, and obtained a quantity of Prussian blue. § 8. Molybdate of lead with black Jlux. — 100 grs. of the ore were mixed with 4 times the weight of black flux. The mixture was then put into a crucible with a piece of charcoal over it ; a cover was fitted to the crucible, and it was placed in a furnace in which a strong heat was kept up during an hour. When the crucible was cold and was broken, there did not appear any reguline button, but shining me- tallic particles were dispersed throughout the mass. It was then reduced to pow- der, and the largest particles were separated by washing, were dried on paper, and weighed 31 grs. ; on examination they proved to be lead in the metallic state. Other particles were separated by a magnet, and the remainder consisted of a black powder. a. Diluted nitric acid was poured on this black powder and dissolved it, ex- cepting a small residuum, which consisted of siliceous earth with a little charcoal. 1. The solution was diluted with distilled water, and filtrated. 2. I then first separated a quantity of lead by sulphuric acid, and afterwards obtained some Prussian blue by prussiate of pot-ash. b. The alkaline solution which had been formed when the melted mass was washed, was poured on a filter, and distilled water was added till it came away tasteless. The filtrated liquor was without colour : nitric acid was then added till the alkali was saturated. When about half of the requisite quantity of nitric acid was poured in, the liquor became pale blue, and as the quantity was increased it changed to green ; and, lastly, when the nitric acid was added till it was in a small excess, the liquor was of a bright amber colour. 1. This solution, with prus- siate of pot-ash, afforded a brown precipitate of molybdaena. 2. Muriate of tin changed the colour to a beautiful deep blue. 3. But sulphuric acid had no effect. c. The amber-coloured solution was evaporated to dryness, and a saline mass of a bright citron-colour remained at the bottom of the vessel. As part of the yellow colouring matter appeared to be only mixed with the salt, I dissolved it in distilled water, and separated a quantity of a citron-coloured powder, which was the mo- lybdic acid. The solution was twice again evaporated, and each time some mo- lybdic acid was separated ; but a part still remained intimately combined with the salt, so as with water always to produce the amber-coloured solution. I now proceeded to examine the ore with the acids. As the results which I ob- tained when the ore was digested with nitric acid were the same as those mentioned c 2 12 PHILOSOPHICAL TRANSACTIONS. [ANNO 17Q6. by Mr. Klanroth, I shall not repeat them, but shall only observe, that it does not appear possible to decompose the ore completely by means of this acid. ^ 9. Molybdale of lead with muriatic acid. — 240 grs. of the purified ore in fine powder were put into a glass matrass, with 3 oz. of pure muriatic acid. The matrass was then placed in a sand bath ; in about an hour the whole was dissolved, excepting some muriate of lead, which I dissolved by pouring water on it. After this there only remained a very small residuum of siliceous earth. a. The solutions were then added together, and formed a liquor which was trans- parent, and of a greenish-yellow colour. 1. Prussiate of pot-ash produced a co- pious precipitate of molybdaena, in the form of a reddish-brown flocculent matter. b. Lixivium of carbonate of pot-ash precipitated a yellowish-white matter, and turned the liquor to a deep blue. c. Carbonate of soda had the same effect, d. Solution of carbonate of ammonia produced a similar precipitate, and caused the liquor to become blue. These precipitates were separately collected and washed on filters. When ex- amined by the blow-pipe, all of them afforded a yellowish-green glass, with phos- phate of ammonia and soda. These precipitates dissolved in diluted nitric acid with effervescence, and sulphuric acid precipitated sulphate of lead, after which Prussian blue was precipitated by prussiate of pot-ash, and the liquor became brown. je. The blue solution, which consisted of the muriatic and molybdic acids com- bined with soda, was evaporated. When the liquor became hot, the colour changed from blue to pale yellow, and the evaporation was continued without any other perceptible alteration till the whole was become a dry concrete salt. I dissolved this salt in distilled water, and added muriatic acid, so as to be in a small excess. The liquor was then evaporated to half, and was set in a cool place. The fol- lowing morning I found a quantity of crystallized muriate of soda at the bottom of the basin, covered with a white flocculent precipitate, which I collected and edul- corated on a filter. The rest of the liquor was repeatedly evaporated, till I had separated the greatest part of this white matter from the muriate of soda. The last portion of the liquor however still contained some molybdic acid, combined with the muriate of soda ; for after it had been several times evaporated and again dissolved, it became blue when muriate of tin was added ; or if muriatic acid was first poured in, prussiate of pot-ash produced a reddish-brown precipitate of molybdaena. Experiments on the ivhite precipitate. — 1. It was not dissolved when water was boiled on it. 2. When digested with sulphuric or muriatic acid, the greatest part was dissolved, and prussiate of pot-ash produced a precipitate of a greenish-brown colour. 3. A small part became yellow when nitric acid was distilled from it. 4. The solutions of carbonate of pot-ash, soda, and ammonia, dissolved the greater part; and when these solutions were saturated with muriatic acid, prus- siate of pot-ash produced precipitates like those of the acid solutions. f. I next examined the blue solution, which consisted of the muriatic and VOL. LXXXVI.] PHILOSOPHICAL TRANSACTIONS. 1 3 molybdic acids combined with ammonia. It was first filtrated, and then gradually evaporated. When evaporated to half the original quantity, the colour was green, but towards the end of the operation it again became blue, and when evaporated to dryness, the residuum was a whitish salt, tinged in some parts with blue. g. This salt was reduced to powder, and was put into a small glass retort, to which a receiver was fitted. I then placed the retort in a small open furnace, and gradually raised the fire till the bottom of it began to melt. The retort was now removed, and the contents examined. The receiver contained some water, and a small quantity of muriatic acid. Near the extremity of the beak of the retort was some muriate of ammonia, with some fuming muriatic acid, and the re- mainder of the tube was filled with a hard greyish-blue salt. In the retort was a black pulverulent residuum. I collected all of the blue salt, and again sublimed it, and again obtained muriatic acid, blue salt, and some of the black powder. The blue salt was composed of muriate of ammonia combined with the acid, or rather with a blue oxyde of molybdaena. h. The black residuum was put into a glass retort, and some nitric acid being poured on it, it was exposed to a moderate heat. Nitrous fumes were discharged, and when the distillation had been repeated, I found the whole of this black pow- der converted into the citron-coloured molybdic acid. I had evident proof that in this experiment a portion of the muriate of ammonia was decomposed by each sublimation, and also that part of the molybdic acid was deprived of oxygen, and remained in the retort, if not in the state of metal, at least combined with so small a quantity of oxygen as to be nearly approaching to it.* Molybdate of lead with muriatic acid. — Exper. 1. 1 dr. of the ore was digested with muriatic acid, and distilled water was added till the whole was dissolved, ex- cepting a small residuum of siliceous earth. The solution was filtrated, and re- peatedly evaporated, till muriate of lead was no longer separated. The muriate of lead, when edulcorated, I found to be perfectly free from any other substance. I now saturated the acid solution, from which the muriate of lead had been separated, with solution of carbonate of ammonia, and obtained a pale yellow flocculent precipitate, which was well edulcorated. This precipitate immediately dissolved in very dilute nitric acid, and with sulphuric acid I precipitated a small portion of lead, after which, with prussiate of pot-ash, I separated a quantity of iron. The solution, when saturated with the ammonia, was deep blue, and was composed of muriatic acid, ammonia, and the blue oxyde of molybdasna, like that mentioned in the former experiment. In the course of these experiments, I have observed that the full blue colour only takes place at the precise moment of saturation, and if the alkali is even added to a considerable excess, the colour does not sutler any further change; but if much water is first added, the blue colour does not appear ; or if water is added after- * A black powder of a similar nature appears to have been obtained hy Scheele, when he distilled the white molybdic acid with a small quantity of olive oil. Essays, p. 238. — Orig. ]6 PHILOSOPHICAL TRANSACTIONS. [ANNO 1796. blue particles. The rest of the solution was then evaporated, and left a bright yel- low mass at the bottom of the matrass. The undissolved residuum of the nitric solution was then boiled with lixivium of pot-ash, which was afterwards saturated with muriatic acid, and became tinged with blue when prussiate of pot-ash was added. The residuum was now a black powder, which was edulcorated, and was immediately dissolved when nitric acid was poured on it; at the same time nitrous fumes were emitted. The solution was transparent, excepting that a few white particles were floating in it. It was then diluted, and filtrated. Prussiate of pot- ash turned it to a brownish green, which afterwards be- came brown. Lixivium of pot-ash precipitated a white flocculent matter; and caustic ammonia, added to a third portion, precipitated a quantity of iron. As this precipitate had some remarkable properties, particularly in respect to the difficulty with which it was decomposed, I have been induced to mention the ex- periments made on it in a circumstantial manner. This precipitate appears from these experiments to be principally composed of iron, and some molybdic acid, to- gether with a small portion of alkali and sulphuric acid. The intimate union be- tween the iron and molybdic acid is apparently the cause which impedes the decom- position of this precipitate; but this can only be ascertained by future experiments on molybdate of iron. I next examined the white precipitate which was deposited by the last evapora- tions, and found that, when distilled with nitric acid, it was converted into the yel- low molybdic acid; and I \va§ therefore convinced that this last portion of the white precipitate was the same neutral salt which I obtained in several other operations, and which has also been noticed by Scheele and Klaproth.* I now began to exa- mine the blue solution b, which consisted of the sulphuric solution of molybdic acid, saturated with ammonia; but that the experiments made on this may be ' better understood, I shall first give an account of some experiments and observa- tions which I have made on the sulphate of ammonia. Experiments and observations on the sulphate of ammonia. — This neutral salt, which from Glauber, who first prepared it, was called the secret ammoniacal salt of Glauber, or vitriolic ammonia, has been very little examined; neither has it been applied to any useful purpose, though the inventor much recommended it in metal- lurgical operations. It has been long known that the fixed alkalies, lime, and barytes, when triturated with it, decompose it, by uniting with the acid. But the effects of heat on it do not appear to have been sufficiently observed. Macquer says, that it is demi-volatile, that it may be sublimed entire, and that it cannot be decomposed in close vessels without some intermediate substance.-f- Baume makes use of nearly the same expressions. J Bucquet says, that when it has lost the * Scheele observes, when molybdaena was detonated with nitre, and the mass afterwards dissolved in water, and saturated with sulphuric, nitric, or muriatic acid, that a white precipitate was produced, which was the acid of molybdaena combined with a portion of alkali. Essays, p. 231 and 240. — Orig. + Diet, de Chimie, torn. 1, p. 111. — % Chimie Exp. et Raisonnee, torn. 1, p. S3\ — Orig. VOL. LXXXVI.] PHILOSOPHICAL TRANSACTIONS. j* water of crystallization, it becomes red-hot, and melts without being volatilized. Lastly, M. Fourcroy mentions it in the following manner: " As it contains much water of crystallization, it immediately liquifies by a very moderate heat; but by degrees it becomes dry, in proportion as the water of crystallization is dissipated. In this state it first becomes red-hot, and soon melts without being volatilized, ac- cording to Bucquet; butM. Baume asserts that it is demi-volatile. In repeating this experiment I have observed, that in fact a part of this salt is sublimed, but a portion remains fixed in the vessel, and doubtless it is concerning this that Bucquet speaks*." When so many eminent chemists concurred in nearly the same assertion, I was not a little surprized to observe, in some experiments made for a very different pur- pose, that the whole of the sulphate of ammonia was not only volatilized by heat but also that the distillation of it was accompanied with some remarkable phe- nomena. I therefore diluted some very pure concentrated sulphuric acid with an equal quantity of distilled water, and having saturated it with ammonia, I gradu- ally evaporated it till it became a concrete salt. Exper. 1 . I put 2 oz. of the salt into a glass retort, capable of containing 3 times the quantity, then fitted on a receiver without any luting, and placed the retort in a small open furnace over some lighted charcoal. The salt in the retort speedily liquified, and a small portion of water first came over ; this was succeeded by a considerable quantity of alkaline gas, which continued to be produced during 15 or 20 minutes. On a sudden the vessels were filled with a thick white cloud, which on close inspection appeared to be composed of very minute glittering crystals. This cload quickly disappeared, and was followed by a great quantity of sulphureous gas and water, the greatest part of which was condensed in the re- ceiver; and the operation went on in this manner while any thing remained in the retort. During the distillation the matter in the retort was always liquid; and when the operation was finished, I found in the receiver a considerable quantity of sulphureous acid, with some ammonia in solution; and in the neck of the retort there was sublimed a portion of the undecomposed salt. From this experiment I was in a great measure convinced, not only that the neutral salt was decomposed, but that the ammonia was also in part resolved into its constituent principles. Exper. 2. That I might however remove any doubt respecting this matter, I fitted a bent glass adopter to a retort, and to this added a double tubulated re- ceiver, from which proceeded a bent tube, which passed under a glass jar filled with water and inverted. The former experiment was now repeated with this ap- paratus; and I had the satisfaction to observe, that when the sulphureous acid began to be produced, a quantity of gas at the same time displaced the water in the jar, and continued to pass into it till to the end of the operation. This gas I afterwards examined, and found that it possessed all the properties of the azotic gas-}-. * Elemens d'Hist. Nat. et de Chimie, torn. 2, p. 93. — Orig. + This operation requires to be conducted with caution ; for at the moment when the white cloud VOL. XVIII. D 18 PHILOSOPHICAL TRANSACTIONS. [ANNO 179& I afterwards distilled 100 grs. of the yellow oxyde of iron, mixed with 200 grs. of sulphate of ammonia. Pure ammonia first came over, and afterwards some sulphureous acid. When the retort began to melt I removed it, and found the iron chiefly in the state of red oxyde, or colcothar, mixed with some sulphate of iron. When oxyde of zinc was used, the residuum was sulphate of zinc. Minium, when triturated with sulphate of ammonia, immediately decomposed it like lime, or the alkalies, and when distilled, the retort contained sulphate of lead. When native green oxyde of copper was distilled with sulphate of ammo- nia, the residuum was partly red oxyde of copper, with some sulphate of the same. But the ammonia came over in a concrete state, by reason of the car- bonic acid contained in the green oxyde. The oxydes therefore of iron, zinc, lead, and copper decompose the sulphate of ammonia by combining with the acid. I next mixed it with the yellow tungstic acid ; but after the distillation, I found the tungstic acid unchanged, excepting that it had acquired a tinge of pale green. The ammonia and the sulphureous acid also came over in the same manner as when only the sulphate of ammonia was distilled. Lastly, I distilled 1 oz. of the sulphate of ammonia with 20 grs. of the yellow molybdic acid. During the distillation, the ammonia and sulphureous acid were produced in as great quantities as when the sulphate of ammonia was distilled by itself. But the molybdic acid remained in the retort, deprived of oxygen, in the form of a black blistered matter, which was again converted into the yellow acid when dis- tilled with nitric acid. From these experiments it appears, that the sulphate of ammonia is not, as many eminent chemists have imagined, incapable of being decomposed without some intermediate substance, but on the contrary, the whole of it can be raised and a great part decomposed, whenever a proper degree of heat is applied; for then a certain portion of ammonia first comes over, so that the remainder is combined with acid in excess, and the hydrogen of the ammonia which remains unites with part of the oxygen of the sulphuric acid, and forms water, which passes into the receiver, accompanied by the acid, now become sulphureous acid, and by the azote in the state of gas. Various methods have long been in use to decompose ammonia. Metallic oxydes produce this effect; and Scheele par- ticularly mentions, that if arseniate of ammonia is distilled, gas is produced, and the acid of arsenic is reduced to the metallic form, and as such is sublimed*. appears, a vacuum takes place, occasioned by the alkaline gas, which previously filled the vessels, being neutralized by the sulphureous gas, which is then produced. It is necessary therefore, in about 10 or 15 minutes after the commencement of the operation, that the fire should be raised, and the azotic gas will then soon begin to pass into the jar. Some water will most commonly rush into the receiver, but if the capacity of this is not too small, there will not be time enough for the water to rise sufficiently high, so as to pass into the retort.— Orig. * Essays, page 155. The same effects were also produced when acid of arsenic was sublimed with muriate of ammonia, p. l6l.— Orig. TOL. LXXXVI.] PHILOSOPHICAL TKANSACTI-ONS. , 1Q The decomposition of the nitrate of ammonia is also well known; and I have no doubt but that muriate of ammonia suffers a similar decomposition in a smaller degree each time that it is sublimed ; for whenever I have had occasion to sublime muriate of ammonia, I have always found some fuming muriatic acid; and from whence could this be produced, but from a portion of the salt which was decomposed during the sublimation. The distillation of the triple salt, com- posed of molybdic acid, muriatic acid, and ammonia (§ 7 and 9,) places this in a stronger light; for whenever this salt was distilled, a certain portion of molybdaena was left in the retort deprived of oxygen, and muriatic acid was found in the re- ceiver. Moreover, from several repetitions of this experiment, I am well con- vinced, that by a great number of sublimations the whole of the molybdaena might have been obtained in the proportion that the muriate of ammonia was de- composed. When all these facts are considered, it appears more than probable that most, if not all, of the ammoniacal salts suffer different degrees of decomposition whenever they are treated in the dry way. As the molybdic acid was my principal object, I did not make all the experiments I could have wished on this neutral salt; neither have I as yet exactly determined the proportion of azotic gas produced from a certain quantity. I have found however, that the sublimed undecomposed part of the salt amounted to 183 grs. when an ounce of the salt had been distilled, and that the liquid in the receiver weighed 145 grs.; so that 152 grs. had escaped, which principally consisted of azotic gas, together with some sulphureous acid, and some alkaline gas, which had made their way out of the vessels during the operation. Continuation of the experiments on the molybdale of lead.— -From the effects which I observed to be produced when sulphate of ammonia was distilled with molybdic acid, I was induced to examine in a similar manner the blue solution b : but first I collected, washed, and dried the pale yellow precipitate which had been formed when the sulphuric solution of the molybdic acid was saturated with ammo- nia*. This precipitate, when dry, appeared of a deeper yellow, and easily dis- solved in muriatic acid. Prussiate of pot-ash was then added to the clear solution, which precipitated the whole of the dissolved matter in the state of Prussian blue. The filtrated solution b was now evaporated till it became a dry concrete salt, the colour of which was pale greyish blue. I collected this salt, and having reduced it to powder, put it into a small glass retort, and having fitted on a receiver, I distilled it in the same manner as was employed with the sulphate of ammonia. The pro- ducts which came over were also the same; and when the bottom of the retort began to be softened by the heat, I removed it, and found the residuum to be a * Whenever the solution was sufficiently diluted, I always found that ammonia precipitated the iron free from any part of the molybdic acid } but when either of the fixed alkalies were used, a portion of molybdic acid was precipitated with the iron into a state similar to the first portions of those white floc- culent precipitates, which have been already mentioned in | 9 and 10. — Orig. D 2 18 PHILOSOPHICAL TRANSACTIONS. [ANNO 1790*. I afterwards distilled 100 grs. of the yellow oxyde of iron, mixed with 200 grs. of sulphate of ammonia. Pure ammonia first came over, and afterwards some sulphureous acid. When the retort began to melt I removed it, and found the iron chiefly in the state of red oxyde, or colcothar, mixed with some sulphate of iron. When oxyde of zinc was used, the residuum was sulphate of zinc. Minium, when triturated with sulphate of ammonia, immediately decomposed it like lime, or the alkalies, and when distilled, the retort contained sulphate of lead. When native green oxyde of copper was distilled with sulphate of ammo- nia, the residuum was partly red oxyde of copper, with some sulphate of the same. But the ammonia came over in a concrete state, by reason of the car- bonic acid contained in the green oxyde. The oxydes therefore of iron, zinc, lead, and copper decompose the sulphate of ammonia by combining with the acid. I next mixed it with the yellow tungstic acid; but after the distillation, I found the tungstic acid unchanged, excepting that it had acquired a tinge of pale green. The ammonia and the sulphureous acid also came over in the same manner as when only the sulphate of ammonia was distilled. Lastly, I distilled 1 oz. of the sulphate of ammonia with 20 grs. of the yellow molybdic acid. During the distillation, the ammonia and sulphureous acid were produced in as great quantities as when the sulphate of ammonia was distilled by itself. But the molybdic acid remained in the retort, deprived of oxygen, in the form of a black blistered matter, which was again converted into the yellow acid when dis- tilled with nitric acid. From these experiments it appears, that the sulphate of ammonia is not, as many eminent chemists have imagined, incapable of being decomposed without some intermediate substance, but on the contrary, the whole of it can be raised and a great part decomposed, whenever a proper degree of heat is applied; for then a certain portion of ammonia first comes over, so that the remainder is combined with acid in excess, and the hydrogen of the ammonia which remains unites with part of the oxygen of the sulphuric acid, and forms water, which passes into the receiver, accompanied by the acid, now become sulphureous acid, and by the azote in the state of gas. Various methods have long been in use to decompose ammonia. Metallic oxydes produce this effect; and Scheele par- ticularly mentions, that if arseniate of ammonia is distilled, gas is produced, and the acid of arsenic is reduced to the metallic form, and as such is sublimed*. appears, a vacuum takes place, occasioned by the alkaline gas, which previously filled the vessels, being neutralized by the sulphureous gas, which is then produced. It is necessary therefore, in about 10 or 15 minutes after the commencement of the operation, that the fire should be raised, and the azotic gas will then soon begin to pass into the jar. Some water will most commonly rush into the receiver, but if the capacity of this is not too small, there will not be time enough for the water to rise sufficiently high, so as to pass into the retort.— Orig. • Essays, page 155. The same effects were also produced when acid of arsenic was sublimed with muriate of ammonia, p. l6l.— — Orig. VOL. LXXXVI.] PHILOSOPHICAL TRANSACTIONS. > ig The decomposition of the nitrate of ammonia is also well known ; and I have no doubt but that muriate of ammonia suffers a similar decomposition in a smaller degree each time that it is sublimed; for whenever I have had occasion to sublime muriate of ammonia, I have always found some fuming muriatic acid; and from whence could this be produced, but from a portion of the salt which was decomposed during the sublimation. The distillation of the triple salt, com- posed of molybdic acid, muriatic acid, and ammonia (§ 7 and 9,) places this in a stronger light ; for whenever this salt was distilled, a certain portion of molybdaena was left in the retort deprived of oxygen, and muriatic acid was found in the re- ceiver. Moreover, from several repetitions of this experiment, I am well con- vinced, that by a great number of sublimations the whole of the molybdaena might have been obtained in the proportion that the muriate of ammonia was de- composed. When all these facts are considered, it appears more than probable that most, if not all, of the ammoniacal salts suffer different degrees of decomposition whenever they are treated in the dry way. As the molybdic acid was my principal object, I did not make all the experiments I could have wished on this neutral salt; neither have I as yet exactly determined the proportion of azotic gas produced from a certain quantity. I have found however, that the sublimed undecomposed part of the salt amounted to 183 grs. when an ounce of the salt had been distilled, and that the liquid in the receiver weighed 145 grs.; so that 152 grs. had escaped, which principally consisted of azotic gas, together with some sulphureous acid, and some alkaline gas, which had made their way out of the vessels during the operation. Continuation of the experiments on the molybdate of lead.— From the effects which I observed to be produced when sulphate of ammonia was distilled with molybdic acid, I was induced to examine in a similar manner the blue solution b : but first I collected, washed, and dried the pale yellow precipitate which had been formed when the sulphuric solution of the molybdic acid was saturated with ammo- nia*. This precipitate, when dry, appeared of a deeper yellow, and easily dis- solved in muriatic acid. Prussiate of pot-ash was then added to the clear solution, which precipitated the whole of the dissolved matter in the state of Prussian blue. The filtrated solution b was now evaporated till it became a dry concrete salt, the colour of which was pale greyish blue. I collected this salt, and having reduced it to powder, put it into a small glass retort, and having fitted on a receiver, I distilled it in the same manner as was employed with the sulphate of ammonia. The pro- ducts which came over were also the same; and when the bottom of the retort began to be softened by the heat, I removed it, and found the residuum to be a * Whenever the solution was sufficiently diluted, I always found that ammonia precipitated the iron free from any part of the molybdic acid 5 but when either of the fixed alkalies were used, a portion of molybdic acid was precipitated with the iron into a state similar to the first portions of those white floc- eulent precipitates, which have been already mentioned in § 9 and 10. — Orig. D 2 20 PHILOSOPHICAL TRANSACTIONS. [ANNO 1706. black blistered matter. I then examined the sulphureous acid and sulphate of am- monia which had risen, but did not find any trace of molybdaena. I next poured nitric acid diluted with an equal weight of distilled water on the black residuum in the retort, and distilled it. As soon as the acid began to be warm, nitrous fumes were discharged, and when the distillation had been repeated with a 2d portion of nitric acid, I found the whole of the black matter converted into a pale citron-coloured substance, which was the molybdic acid. $11. Analysis of the molybdate of lead. — I put 250 grs. of the purified ore re- duced to a fine powder into a glass matrass, and having poured on it 1 oz. of con- centrated sulphuric acid, I digested it in a strong heat during an hour. When the solution was become cool and had settled, the acid was cautiously decanted from the powder, and distilled water was poured on till it came away tasteless. The same operation was repeated twice, so that 3 oz. of sulphuric acid were used. The acid solutions and washings were then filtrated, and were received in a large glass vessel. I diluted the pale blue liquor with distilled water, in the proportion of l6 to 1, and afterwards gradually added ammonia till it was completely saturated. The liquor then became deep blue, and appeared turbid. When it had stood about 24 hours, a loose pale ochry precipitate subsided, and was collected on a filter, the weight of which had been noted*. This precipitate was edulcorated, and after- wards dried with the filter on the flat top of a tin vessel heated by boiling water, after which the weight of the precipitate was 4.2 grs. The colour of the dry pre- cipitate was yellowish brown, and when dissolved in muriatic acid it was precipitated by prussiate of pot-ash in the state of Prussian blue. I now poured part of the clear blue solution, which was composed of sulphuric and molybdic acid saturated with ammonia, into a glass retort, and when about half was evaporated, I continued to add the remainder of the liquor at different times till the whole was become a concrete salt. I then raised the fire and continued the distillation till all the sulphate of ammonia was decomposed or driven over: but as some of the sublimed salt was fixed in the neck of the retort, I turned the bottom of it upwards, and poured some distilled water into the neck, so as to wash out the salt; after this I increased the fire till the whole body of the retort was be- come red-hot -f-. The residuum in the retort was a black blistered mass, on which I poured 3 oz. of nitric acid diluted with an equal portion of water, and having dis- tilled it, I repeated the operation, and thus converted the whole of the black * This is one of the many instances which prove the weak affinity between molybdaena and oxygen ; for it is well known that pure ammonia precipitates iron from sulphuric acid, in a state nearly similar to martial aethiops ; but in the present case the iron takes a considerable portion of oxygen from die molybdic acid at the moment that the acid menstruum is saturated by the ammonia, and it is therefore precipitated in the form of a yellowish-brown oxyde, while the molybdic acid being thus deprived of so large a quantity of oxygen, is converted into a blue oxyde which remains in solution. — Orig. + To be certain that all of the ammoniacal salt is decomposed, it is absolutely necessary that the retort should he made red-hot. — Orig. VOL. LXXXVI.] PHILOSOPHICAL TRANSACTIONS. 21 matter into the yellowish acid of molybdaena. When the retort was sufficiently cooled, I cut off the neck, and removed the powder, which weighed Q5 grs. I next proceeded to decompose the residuum left by the acid solution in the state of sulphate of lead; and having edulcorated it, I boiled it during an hour with 4 oz. of lixivium of carbonate of soda, then washed the powder, and poured on it nitric acid much diluted. The whole was dissolved, excepting a small portion of white powder, which was washed and dried on a filter by the heat of boiling water, and then weighed TV of a grain. This on examination, proved to be siliceous earth. I then exactly saturated the nitric solution with lixivium of pure or caustic soda, and having washed and dried the precipitate of 4ead, I exposed it in a porcelain cru- cible for a -^ of an hour to a heat rather below red ; after which it weighed 146 grs. As I had found by a former experiment that a G small portion of iron remained with the lead, I Oxydeoflead 14 j£. 24f J 1 gr. ■ By this analysis, 250 grs. of the ore yielded 25° ° as annexed, and lost 3.1, which I am inclined to place principally to the account of the lead, as it is scarcely possible to decompose the sulphate of lead without some loss, occasioned by the action of the alkaline solution. § 12. Experiments on the yellow molybdic acid, obtained by the analysis.— a. When exposed to the blow-pipe on charcoal, it was melted by the exterior flame, and the sides of the charcoal were covered with small long crystals, which had a metallic lustre resembling silver*. When the heat was continued, the whole was melted, and for the greater part absorbed by the charcoal, the edges of which became covered with a blue powder. When melted in a spoon of platina, some yellow powder was deposited near the edges, and a brownish yellow shining matter was formed, which became streaked in cooling. With borax it produced a brownish-yellow glass, but when the quan- tity of molybdic acid was small, the colour was sometimes blue when the globule was heated by the interior flame. With soda in the platina spoon it formed a brownish opaque matter. And with phosphate of ammonia and soda it formed a glass, which, in proportion to the quantity of molybdic acid, varied from a greenish blue to a deep blue. b. 10 grs. of the yellow molybdic acid were boiled with 6oz. of distilled water. About 3 grs. were dissolved, and the solution when filtrated was of a pale yellow * Scheele mentions a similar product obtained when molybdaena was exposed to the blow-pipe. Essays, p. 23o. — Also by sublimation. Essays, p. 238. — And Mem. sur la Molybdene, par M. Pelletier. Journ, de Phys., Dec. 1785, p. 439-— Orig. 22 PHILOSOPHICAL TRANSACTIONS. [ANNO 1790. colour. It had scarcely any perceptible flavour, but turned litmus paper red. When prussiate of pot-ash was added to a portion of the solution, no apparent change was effected; I therefore added a small quantity of nitric acid, which produced a copious brown precipitate of molybdaena. The sulphuric and muriatic acids had the same effect, when poured into the solution, either before or after the addition of prussiate of pot-ash. With muriate of tin it changed to a beautiful deep blue. Lead was precipitated from solution of nitrate of lead, in the form of a pale yellow precipitate, which was a regenerated molybdate of lead. Nitrate of barytes rendered the solution slightly turbid, but I did not find that the precipitate which subsided was soluble in cold water, as Scheele has mentioned*. The solution did not precipitate lime from nitric acid. c. 10 grs. of the yellow molybdic acid were dissolved when digested with 1 oz. of concentrated sulphuric acid. The solution as it cooled became blue.-f- Prussiate of pot-ash produced a^reddish-brown precipitate. Muriate of tin had no effect. When a portion of the solution was distilled to dryness, the yellow molybdic acid was left in its original state.J The remainder of the solution was saturated with lixivium of soda, by which the blue colour was heightened, and some white floc- culent matter was precipitated. Prussiate of pot-ash added to part of this saturated solution did not precipitate the molybdaena, till the alkali was again supersaturated with an acid. Muriate of tin poured into the solution saturated with alkali, changed it to a deep blue ; but when the alkali was again saturated with an acid the muriate of tin ceased to have any effect. The white flocculent matter which was precipitated when the solution was saturated with soda, was edulcorated and heated with nitric acid, by which it was converted into a yellow powder, similar to the molybdic acid which had been dissolved. d. 10 grs. of the yellow molybdic acid, when digested in a strong heat with 1 oz. of concentrated muriatic acid, formed a pale yellowish-green solution. Prussiate of pot-ash precipitated the molybdaena. Muriate of tin had not any effect. A portion of the solution being distilled to dryness, left a greyish-blue residuum. § I then saturated the remaining part of the solution with lixivium of pot-ash, by which the blue colour became more apparent and a much larger quantity of white flocculent matter was precipitated than when soda was employed. Prussiate of pot-ash did not affect this solution, till the alkali was again saturated with an acid. Muriate of tin was precipitated by the solution saturated with alkali, highly coloured with blue ; but when the alkali was again saturated with an acid, the muriate of tin had no * Essays, p. 234. — Scheele does not mention the quantity of water which he employed. — Orig. + Scheele observes that sulphuric acid dissolves a considerable quantity of molybdic acid, and that the solution as it cools becomes blue and thick ; but when heated, the colour disappears, and returns again as the liquor cools. Essays, p. 235. — Orig. \ M. Pelletier says, that a small portion of molybdaena is raised by sulphuric acid when distilled with it ; but I did not find it so with the molybdic acid. — Mem. sur la Molybdene, Journ. de Phyi . Dec. 1785.— Orig. if Scheele has made the same observation. Essays, p. 235. — Orig. VOL. LXXXVI.] PHILOSOPHICAL TRANSACTIONS. 23 effect.* Lastly, the white flocculent matter was boiled with nitric acid, and be- came like the molybdic acid before it was dissolved. e. Nitric acid did not appear to have any effect on the molybdic acid when di- gested with it. f. 2 oz. of lixivium of carbonate of pot-ash were poured on 10 grs. of the molyb- dic acid. In a few minutes carbonic acid was gradually expelled, and as the molyb- dic acid dissolved, a white flocculent matter was deposited. After it had stood some hours, the clear liquor was decanted from the residuum. Prussiate of pot-ash did not affect this solution. Some nitric acid was then dropped in, and produced a reddish-brown precipitate, which was re-dissolved till the acid was in some excess. Muriate of tin, when added to a portion of the alkaline solution, was precipitated white, but when some muriatic acid was dropped in, the precipitate became blue. The white flocculent residuum, when treated with nitric acid as in the former experiments, was converted into the yellow molybdic acid. Another portion of the alkaline solution was evaporated to 4, and in proportion as the evaporation ad- vanced, some of the white flocculent matter was precipitated, but I did not obtain any crystals. g. 1 oz. of lixivium of carbonate of soda were poured on 10 grs. of molybdic acid. In a few minutes carbonic acid was expelled, and when the molybdic acid was dis- solved, a small quantity of white flocculent matter was precipitated. The clear solu- tion was then poured from the residuum. Prussiate of pot-ash did not produce any precipitate till the alkali was saturated with an acid. The effects of muriate of tin were also the same as those mentioned in the former experiment. A part of the solution was evaporated to half, and the next morning I found crystals, which, though not very distinct, appeared to be in the form of four-sided tables with the angles truncated. These crystals dissolved in water without leaving any residuum, and when the solution was saturated with muriatic acid, the molybdic was precipi- tated by prussiate of pot-ash, as in the former experiments. h. 1 oz. of carbonate of ammonia in solution were poured on 10 grs. of molybdic acid, which appeared to be more readily dissolved than when the fixed alkalies were employed. The solution appeared slightly turbid, but very little of it was precipi- tated. The effects produced by prussiate of pot-ash and muriate of tin were the same as in the preceding experiments. When a portion of the solution was distilled to dryness, part of the molybdic acid remained unchanged, but another part was de- prived of oxygen, and appeared in the form of»a dark grey powder. The remaining part of the solution was considerably evaporated ; and the following day I found a * From the effects produced by muriate of tin on the molybdic aeid dissolved in water, in acids, and in alkalies, it appears that it always tends to deprive the molybdic acid of a great part of its oxygen ; and when water is the menstruum, the muriate of tin does this effectually ; but when the molybdic acid is dissolved in sulphuric or muriatic acid, the muriate of tin has no effect, because, as I conceive, the oxygen is supplied by the acid menstruum. This seems the more evident from the effects produced by the muriate of tin when the excess of acid is saturated by an alkali. — Orig. 24 PHILOSOPHICAL TRANSACTIONS. [ANNO 179$. striated yellowish mass, which dissolved in water without leaving any residuum. This solution resembled the former in every respect.. § J 3. Molybdic acid with, sulphur. — To remove every doubt concerning the nature of the yellow acid obtained by the analysis, I made the following experiment. I put 20 grs. of the yellow acid and 100 grs. of sulphur into a small glass retort, and continued the distillation till the bottom began to melt. The residuum was a black substance, which was greasy to the touch, stained the fingers black, communicated to them a shining metallic lustre, and had all the other properties of the mineral known by the name of Molybdaena. I afterwards distilled this black matter with nitric acid, which converted it into a yellow powder, similar in appearance and pro- perties to the molybdic acid which had been originally employed. § 14. General Observations. — It has been proved in the course of this paper, that molybdate of lead can be decomposed in the humid way by the fixed alkalies, though these have no effect when boiled with molybdaena mineralized by sulphur.* The state of the molybdaena in the 2 substances appears to be the cause of this differ- ence, for in the former it is oxygenated, but in the latter I conceive it to be in the state of metal. From the experiments of Scheele it also appears, that of all the known acids only 2 have any effect on the sulphurated molybdaena, and that these 2 are the nitric acid, and that of arsenic. The latter however seems rather to act on the sulphur than on the molybdaena ; but the former communicates oxygen to both, so to convert the one into sulphuric and the other into molybdic acid. The rapidity with which nitric acid oxygenates molybdaena, even to super- saturation, resembles the effects produced by the same acid on some other metallic substances, particularly tin ; for in both cases the acid ceases to act as soon as the supersaturation with oxygen is effected; and on this account the nitric acid is unable to dissolve the molybdic acid. Before proceeding I must observe that whenever a solution of the molybdic acid becomes blue, or tending towards that colour, it is a certain sign that the molybdic acid has suffered a diminution of oxygen. A variety of facts which prove this, have been already brought forward in the different experi- ments contained in this paper ; and I shall soon have occasion to mention others. Sulphuric acid can disolve a considerable quantity of molybdic acid ; and the solution is always more or less of a blue colour according to the quantity dissolved ; and the blue colour proves that the molybdic acid has parted with a portion of oxygen ; but if the solution be heated, the blue colour disappears, and returns again when the liquor becomes cold.-f~ The cause of this I believe to be a change produced by heat in the respective de- grees of affinity which prevail between the metallic base and oxygen, and between the base of the acid menstruum and oxygen ; so that when the solution is heated, the affinity between the blue oxyde of molybdaena and oxygen is increased, and a * Scheele's Essays, p. 230 j and Mem. sur la Molybdene, par M. Pelletier. Journ. de Phys. 1785, D. 437. — Orig. + When lead or any other metal is present, the blue colour is permanent. — Orig. VOL. LXXXVI.] PHILOSOPHICAL TRANSACTIONS. 25 portion of oxygen therefore quits the acid menstruum, and combines with the blue oxyde, which then becomes molybdic acid ; but as soon as the heat is dissipated, the cause of this augmentation of affinity ceases, and the acid menstruum receives again the portion of oxygen from the molybdic acid, which then returns to the state of a blue oxyde ; or if the heat is continued till the solution is distilled to dryness, the residuum is the molybdic acid exactly in the same state as it was before the solution was made; for the continuation of the heat enables it to retain the portion of oxygen requisite to constitute a metallic acid. I do not therefore believe that the total quantity of oxygen in the solution suffers alteration any further than that it is dis- tributed in different proportions between the 2 acidifiable bases, sulphur and molyb - daena, according to the temperature of the solution. As the affinity between azote and oxygen is comparatively weak, the metal molybdaena effects a decomposition of the nitric acid, and acquires a sufficiency of oxygen to become molybdic acid. But as the affinity between sulphur and oxygen is greater than that of azote, and also under certain circumstances superior to molybdaena, the latter requires the assistance of heat to be able to retain a full por- tion of oxygen, and this increase of affinity lasts no longer than during the con- tinuation of the heat. To corroborate this assertion, it will be proper to consider the effects of muriatic acid on that of molybdaena, especially as the affinity between the radical principle, or base of the muriatic acid, and oxygen, is known to be so great, that no chemist has as yet been able to effect a separation of the constituent principles. It has been mentioned, that molybdic acid when dissolved in muriatic acid, also parts with some oxygen, and tinges the menstruum with a green colour. But heat does not enable it to take back the oxygen, for it augments the effects of the mu- riatic acid, which, when distilled, passes oxygenated into the receiver, and the molybdic acid is converted into a bluish grey oxyde.* These effects clearly prove, that heat in this case acts inversely to what it did when the nitric and sulphuric acids were the menstrua. For then the increase of affinity was between molybdaena and oxygen, but here it is in favour of the base of muriatic acid ; so that by the con- tinuation of heat, the muriatic acid carries with it into the receiver a certain portion of oxygen, which it has taken from the molybdic acid, and the latter is left in the state of an oxyde. From this it appears that muriatic acid uniformly tends to deprive the molybdic acid of a certain quantity of oxygen, and that heat produces a contrary effect on this solution to that which it did on the one made with sulphuric acid ; and heat and cold do not therefore produce a change of colour. I do not however believe that muriatic acid acts thus constantly on all those metals which can be dissolved by it ; on the contrary, there is a muriatic solution much resembling the sulphuric so- lution of molybdic acid in the vicissitudes of colour which it exhibits by heat and cold. * Elemens d'Hist. Nat. et de Chimie, par M. de Fourcroy, tome 2, p. 439. — Orig. VOL. XVIII. E 26 PHILOSOPHICAL TRANSACTIONS. [ANNO \7Q6. The phenomena which heat produces on the solution of cobalt in muriatic or nitro-muriatic acid, called sympathetic ink, have long engaged the attention of chemists and others, but as yet great difficulties have occurred whenever an expla- nation has been attempted. There can be no foundation for the idea which some have had, that the green colour, which characters traced with this solution on paper assume when heated, is caused by a temporary crystallization of the salt, and the disappearance of the colour by a subsequent degree of deliquescence ; because any quantity of the liquid becomes green when heated. The effects caused by heat on the sulphuric solution of molybdic acid have there- fore induced me to suspect a similar cause in the muriatic solution of cobalt ; and I believe that heat and cold in like manner causes a temporary difference to take place in the proportions of oxygen existing in the acid menstruum and the oxyde ; and this is the more confirmed when the acid is expelled by too great a degree of heat, for then the changes of colour are no longer to be observed. Heat, it is well known, assists the combination of oxygen with the metals, but I do not be- lieve that the above-mentioned alternate effects of heat and cold have been as yet investigated. It is probable that these are not confined to the two instances which have been adduced, though in other solutions they may not be so apparent. The subject is certainly curious, and worthy of the attention of chemists, as it would re- flect much light on the solutions of metals in general. When the sulphuric or muriatic solutions of the molybdic acid are saturated with pot-ash or soda, they assume a very deep blue colour at the moment of saturation. The molybdaena is not however precipitated in the form of the blue oxyde, but for the greater part remains combined with the acid menstruum and the alkali, and thus forms a triple salt in solution, which differs considerably from another triple salt, which is slowly precipitated at the time of saturation in the form of a white flocculent matter, and is composed of the same 3 ingredients, but contains the oxyde in the largest proportion. Sometimes a 4th ingredient becomes added to the last mentioned white precipitate ; for when iron is present in the sulphuric or muriatic solutions, it is precipitated by pot-ash or soda intimately combined with the other ingredients, and appears to render the decomposition of the precipitate very difficult. Though the triple salt which is in solution will pass many folds of paper without leaving any residuum, yet it is not permanent ; for by repeated eva- porations, the neutral salt resulting from the combination of the acid menstruum and the alkali becomes crystallized, and a white flocculent matter is separated, which does not contain iron like that which was precipitated when the acid solution was saturated with the alkali, but can be converted into the yellow molybdic acid by be- ing distilled with nitric acid, which takes from it the small portion of the acid men- struum and the alkali required to constitute the triple salt. It has already been observed, that nitric acid has no effect when immediately digested on molybdic acid, but I have found it otherwise when a 3d substance was present ; and the effects were nearly the same whether this substance was a metal VOL. LXXXVI.] PHILOSOPHICAL TRANSACTIONS. 27 or an alkali. The portion of molybdic acid which I detected in the nitric acid em- ployed to purify the ore, and Mr. Klaproth's experiments made with the same acid, prove the first, and the experiment mentioned in ^ 8 is a proof of the latter. The phenomena which appeared in the last experiment throw some light on the effects produced by nitric acid on molybdaena ; for when the sulphuric and muriatic solu- tions of the molybdic acid were saturated with pot-ash or soda, they gradually changed to yellowish green, and so on to blue, in proportion as the alkali was added; but when nitric acid was added to the alkaline solution, the change of colour was exactly the reverse of the former, for the changes were then blue, green, and yel- low, in proportion to the quantity of nitric acid. The cause of these effects I conceive to be the different degrees of oxygenation of the molybdaena ; for when the first portion of nitric acid was added, it rather com- bined with the alkali than with the molybdic acid, and the latter was therefore in some degree separated with a diminution of the original quantity of oxygen, and consequently appeared as the blue oxyde in solution. After this, the 2d portion of nitric acid began to oxygenate the blue oxyde, and therefore changed the colour of the solution to green ; but the 3d addition of nitric acid acted immediately on the oxyde, turned the solution yellow, and when assisted by heat, caused a quantity of the yellow molybdic acid to be precipitated. The alkali however appears to have impeded the complete separation of the molybdic acid, and retained a part of it to- gether with the nitric acid, so as to form a yellow triple salt. When the sulphuric and muriatic solutions of the molybdic acid are saturated with ammonia, triple salts are formed, which are different in their properties from those which have been de- scribed ; for the triple salts produced by ammonia are permanent, and do not appear to be decomposed by evaporation. When iron is present in the acid solution, sufficiently diluted, it is precipitated by ammonia free from molybdic acid, especially when the menstruum is the sul- phuric acid. The affinity of the molybdic acid with muriate of ammonia is so great, that by sublimation it even in part quits lead to unite with it, and then forms the blue triple salt, from which the blue oxyde does not separate, but in proportion as it is deprived of oxygen by the gradual decomposition of the ammonia caused by re- peated sublimations. When the sulphuric solution saturated with ammonia is evaporated to a proper degree, the triple salt crystallizes in the usual figure of the sulphate of ammonia, but the colour is bluish green. When however the evaporation is continued to dry- ness, a pale greyish-blue salt is left, and by distillation this salt is decomposed, after the manner of the decomposition noticed in the sulphate of ammonia, and the molybdaena remains in the form of a black powder, deprived of oxygen. I think it necessary here to observe, that when molybdaena is not in the metallic state, it appears to suffer 4 degrees of oxygenation. The first is the black oxyde ; the 2d is the blue oxyde ; the 3d is the green oxyde which, as it seems to be inter- e 2 28 PHILOSOPHICAL TRANSACTIONS. |~ANNO I796. mediate between an oxyde and an acid, I am inclined to call molybdous acid, ac- cording to the distinction made by the new Nomenclature ; the last and 4th degree is the yellow acid, or that which is supersaturated with oxygen. The affinity between molybdaena and oxygen is but weak, at least in respect to that portion which is required to constitute molybdic acid ; for it has been proved, in the course of these experiments, that considerable changes are produced by a very small difference in the proportions of the acids or alkalies, and even by the degrees of heat. Scheele and Mr. Islmann have observed, that all of the metals, excepting gold and platina, are able in the humid way to deprive the molybdic acid of oxygen, so as to cause it to become blue ; but here their effects appear to cease. M. Pelletier found that a solution of molybdic acid was turned blue when hydro- genous gas was passed through it. Mr. Klaproth has also remarked that light, under certain circumstances, changed the colour of molybdic acid to blue. And the effects of light appear in some measure to be connected with the following experiment. I made a solution of the molybdic acid, by digesting sulphuric acid on molybdate of lead, and diluted it with an equal quantity of water. The solution was filtrated, and I then added a solution of hepar sulphuris till the brownish-red precipitate which was produced began to fall much paler. After this the liquor was filtrated, and was of a pale beer colour. I placed it accidentally in an open glass jar, on a shelf near a window, on which the sun shone during a great part of the day, and was surprized to observe that in about 2 days it began to assume a greenish tinge, which gradually became deeper ; on the 3d day it was of a full green, on the 4th it had a tinge of blue, on the 5th the colour was greenish-blue, and on the Oth day it was changed to a beautiful deep blue. The solution continued all the time to be transparent ; and though the vessel remained 4 weeks in the same situation, the blue colour suffered no further change. This solution much resembles that which Scheele discovered in the course of his experiments on manganese ; but the apparent similar effects, I believe, are produced by opposite causes ; for the changes of co- lour in the alkaline solution of manganese appear to be effected by the absorption of oxygen, but those of the molybdic solution are caused by a diminution of the in- herent quantity. The contrast of the causes which operate on the 2 solutions becomes the more evident when the effects which acids produce on them are considered ; for when a few drops of an acid are added to the solution of manganese, the changes of colour are accelerated, not merely by the neutralization of the alkali and consequent pre- cipitation of the manganese, but, as I conceive, by the accession of oxygen either mmediately from the acid, or from the atmosphere, which the manganese is better able to absorb when the disengagement of it from the alkali is thus assisted by the addition of the acid. On the contrary, when nitric acid is dropped into the molybdic solution, the colour is immediately destroyed, in the same manner as in all the other blue solutions of molybdaena when oxygen is thus presented to them. The Y0L. LXXXVI.] PHILOSOPHICAL TRANSACTIONS. 29 facility with which molybdaena parts with oxygen is evinced not merely in the humid way, for M. Pelletier found that molybdic acid yielded oxygen to arsenic when dis- tilled with it, and that the latter was converted into a white oxyde. The same is also proved by my experiments on various oxydes distilled with sulphate of ammonia; for the molybdic acid was the only one which could thus be deprived of oxygen, not excepting the tungstic acid, which has been supposed much to resemble that of molybdaena. XIII. Observations of the Diurnal Variation of the Magnetic Needle at Fort Marlborough, Sumatra. By John Macdonald, Esq. p. 340. These observations were carefully made in a wooden building, having nothing of iron near it. They were taken 3 times mostly every day, at the hours of 7 or 8 in the morning, and at noon, and 4 or 5 afternoon ; from June 27, 1794, till the middle of March 1795- The thermometer was commonly at about 80°. It appears from these observations, that the diurnal east variation of the variation, increased from about 7 in the morning till 5 in the afternoon, and that it thence decreased till 7 in the morning. The whole variation was, on a medium, about 1° 8' east ; and the change in the variation, between morning and evening, 2 or 3'. It appears in general, that such diurnal variation of the variation as had been observed during thunder, is greater than it ought to have been, caeteris paribus. It has been remarked, that heat weakens the magnetic virtue, and that cold strengthens it. Supposing, with Dr. Halley, the existence of 4 magnetic poles, by blending this supposition with the above principle well ascertained, attempts have been made to account for the diurnal variation of the variation. The south-east mag- netic pole being less heated in the morning, either by the sun or by subterraneous fire, than towards noon, and in the afternoon, and being at the same time, by passing through the meridian of Celebes, nearer Sumatra than the south-west mag- netic pole, it draws to it in the morning the south end of the magnetic needle more powerfully than the other attracts ; and consequently the diurnal variation of the variation ought to be, and actually is, less in the morning than in the afternoon. In the progress of the day, the south-east magnetic pole having become heated, and the south-west pole being at the same time less heated, attracts the south end of the magnetic needle more powerfully than the other does ; and hence the east diurnal variation of the variation appears greater in the afternoon than in the morn- ing. It is found in Europe, that this diurnal variation of the variation is greater in summer than in winter. This seems to point out heat acting on magnets in the earth, as its efficient cause. This was first observed in Europe in 1756, by Mr. Canton ; and the results of the foregoing observations being diametrically opposite to his, with similar effects, afford not a small confirmation of the essential part of Halley's theory. From the greatness of the angle of dip of the needle, we are led to suppose that the magnetic poles are fixed within the magnetic nucleus far within the earth's sur- SO PHILOSOPHICAL TRANSACTIONS. [ANNO 17Q6. face, and that some of these poles are more powerful in their action than others, from the variation observed in various places of the globe. XIV. Discovery of some very Singular Balls of Stone, found in the Works of tTie Huddersfield Canal. By Mr. Benj. Outram, Engineer, p. 350. The Huddersfield canal is to be carried through that chain of mountains which extends from the Peak of Derbyshire, in a northward direction through Yorkshire, &c. into and through a great part of Scotland, by pursuing from the navigation at Huddersfield a deep and narrow valley to Marsden, where it enters the north- eastern foot of one of these mountains, called Pule Hill, under which it is to be extended south-westwardly by a subterraneous cut or tunnel to the foot of Stand Edge Hill, or Brunn Clough, where it again excavates ; and pursuing the bottom of a deep valley into Saddleworth, passes along the banks of the Tame to Ashton- under-Lyne, where it joins the canals that extend to Manchester, Stockport, Peak Forest, &c. In the latter end of the year 1794, the miners employed by the canal company began to perforate the north-eastern foot at Pule Hill : the strata they first cut through consisted of a greyish coloured shale, the beds or laminae of which did not lie quite horizontal, but dipped or declined a little to the westward. The strata continued regular till the workmen had perforated about 240 yards in length from the entrance of the hill, and were about 80 yards deep from the surface of the ground immediately over them, when they discovered on the north side of their work a fault, throw, or break of the strata, which was filled with shale, reared on the edge, and mixed with softer earth, and in some places with small lumps of coal. In con- tinuing to pursue the direction of the tunnel, this fault occupied by degrees more of the space of the tunnel, for about 40 yards in length, when it nearly occupied the whole tunnel, which is near 4 yards in width': and at about 5 feet from its southern mar- gin it contained a rib of lime-stone, near 4 feet thick in the bottom, but not quite so thick at the top of the tunnel ; and on each side of this rib it contained balls of lime-stone promiscuously scattered, and of various sizes, from 1 ounce to upwards of 100 lbs. weight. The rib and balls of lime-stone were first found at about 280 yards from the north-eastwardly end of the tunnel, where it is about 90 yards in perpendicular depth from the surface ; and the workmen have now pursued the tunnel to near 350 yards from the entrance, and the rib of lime-stone and balls continue nearly the same ; the rib has varied a little in thickness, and has not pursued a straight line ; in one place it nearly left the tunnel to the northward, but in a few yards turned southward, to its former direction. The lime-stone of the rib is not per- fectly pure, that in the balls is still less so, but it makes a good lime for cement. The balls when broken appear to be mixed with a kind of pyrites, in small particles, near their outward edges ; their form is very peculiar, being similar in all their * VOL. LXXXVI.] PHILOSOPHICAL TRANSACTIONS. 31 sizes ; it is not perfectly globular, being flattened a little on two opposite sides, which appear to have been the poles when in a revolting state ; and each ball is more or less furrowed in a latitudinal direction, as if, when revolving round its axis, and taking its fixed state from a more fluid one, it had met with some resist- ing substance. Though the surface of this country is very rocky, it does not discover lime-stone any where within 20 miles of this tunnel ; yet if the strata near the lime-stone at Buxton to the south, and at Clitheroe to the north, are examined, it will appear probable that the base of these hills is lime-stone at some depth, and this fault dis- covered in the shale probably extends from the lime-stone bed beneath ; and the rib of lime-stone and balls which, with other mixed substances, fill up this crevice or fault, were probably thrown thither from the mass beneath, by the volcanic erup- tion which first occasioned this break in the strata, or by some subsequent eruption of the same kind. XV. Account of the Earthquake felt in Various Parts of England, Nov. 18, 1795. By Edw. Whitaher Gray, M. D., F.R.S. p. 353. This earthquake happened about 1 1 o'clock at night, of the day above-mentioned. It appears that the shock was felt as far to the north as Leeds, and as far to the south as Bristol. To the east it was felt as far as Norwich, and to the west as far as Liverpool. Its extent from north to south therefore was about 105 miles; and its extent from east to west about 175. In this latter direction, or rather from north-east to south-west, it may be said to have reached nearly across the island. The counties in which it has been perceived are, Somerset, Wilts, Oxfordshire, Buckinghamshire, Northamptonshire, Huntingdonshire, Norfolk, Lincolnshire, Leicestershire, Warwickshire, Gloucestershire, Herefordshire, Worcestershire, Staffordshire, Cheshire, Derbyshire, Nottinghamshire, Yorkshire, and Lancashire. To which may probably be added the counties of Rutland, Berks, Bedford, Cam- bridge, and Shropshire. I have not indeed met with any account of the earthquake from either of them; but, whoever will examine the situation of these counties, with respect to those above enumerated, will find it difficult to conceive that they were not, in some degree, affected by it. The accounts of it from different places are nearly alike: the duration about 2 seconds. From Worcester the following account of it was sent by Dr. Johnstone of that city, in a letter dated Nov. 24 ; which may be considered a pretty good specimen of the several accounts. " The earthquake was chiefly felt by persons in bed, about 1 1 o'clock, or 5 minutes after, who describe the sensation to have been as if some person under the bed had heaved it up. That sensation was preceded, the instant before, by a noise which some call rumbling, and which others compare to the falling of tiles, though none fell from the houses where they lived. Many persons heard the windows and doors of their rooms rattle at the same time, which 32 PHILOSOPHICAL TRANSACTIONS. [ANNO 17Q6. increased their alarm. Thunder and lightning had been observed some days before; and several persons, of a delicate state of ^health, passed the night of the 1 8th in a restless uneasy manner, without knowing why, though very much in the manner in which they used to be affected by thunder and lightning." In Derbyshire the shock appears to have been very severe. A description of its effects, not only on the earth, but also under its surface, is contained in the two following letters from Mr. Wm. Milnes, of Ashover: the first is dated Nov. 20. " On Wednesday night, about a quarter past 1 1 o'clock, a severe shock of an earth- quake was felt here. I felt it very sensibly ; at first I heard a rumbling kind of noise, and immediately after it appeared as if some persons had violently forced into the room; the bed, and every thing else, shaking very much. The workmen in Gregory mine were so much alarmed by the noise, and the sudden gust of wind that attended it, as to leave their work; some expecting that the whole mass of bunnings above them, which contains many hundred tons weight of rubbish, had given way, and that they should be buried in the ruins; others, who were at work near the new shaft, supposed that the curb which supports the walling had given way, and the whole shaft had run in. Several chimnies were thrown down, and several families left their habitations; indeed such a general alarm was never known in this neighbourhood." The gust of wind mentioned by Mr. Milnes being considered as a remarkable circumstance, he was desired to make some further inquiry concerning it: in con- sequence of which a second letter was received from him, dated Dec. 4, as follows. " I have examined all our miners separately, and, from the following circumstances, I think there cannot be a doubt but the wind which was felt in the mines, on the ] 8th of last month, rushed into the shafts from the surface. Those men who were at work in the pumps, which are a considerable depth below the waggon gates, and have no communication with thern, did not feel the wind; but heard in the first place, a rushing rumbling kind of noise, which appeared to be at a distance, and to come nearer and nearer, till it seemed to pass over them, and die away, Those who were in the waggon gate which has a communication with the engine shaft, and the new shaft, felt a very strong current of wind: which, one man says, con- tinued while he walked about 6 or 7 yards, and came along the gate, as if it came from the new shaft ; he had no light, but, as he went along the gate, its sides, where he laid his hands, felt as if they were going to close in upon him. " The only one who saw any appearance of light, on that evening, in this neighbourhood, was a person who lives with Mr. Enoch Stevenson, the miller, at Mill Town, He informs me that, as he and another man were returning from Tideswell, he saw, when he got on a piece of high land near Moor-hall, on the road to Chatsworth, an uncommon light; and, when looking towards Chesterfield, the sky appeared to be open for about the length of a mile, the colour pale red, and continued so while he awakened his fellow servant, who was asleep in the VOL. LXXXVI.] PHILOSOPHICAL TRANSACTIONS. 33 waggon, to show him the strangest flash of lightning that ever was seen. From his description, the range of it was from east to west ; and so low in the horizon, that, had he not been on high ground, he could not have seen it." XVI. Newton s Binomial Theorem Legally Demonstrated by Algebra. By the Rev. Wm. Sew ell, A.M. p. 382. *» Let m and n be any whole positive numbers; and (l -{- XY a binomial to be ex- panded into a series, as 1 + ax -f b*2 •+- ex3 + &c. where a, b, c, d, &c. are the co-efficients to be determined. m Assume vm = (l + x)~" = 1 -f- ax + bx* -f ex3 -f- d,t4 -f- &c. m And zm = (1 + y)~n = 1 + Ay + By2 + cy3 + dj/4 -f &c. Then will vn = 1 -f x, and z" = 1 -j- y ; .-. vn — • ' zn = » — y. And i/» — zm = a X (# — y) + b X (a?a — #2) + c X (#3 — y5) + &c. Consequently *„ ~ * „ = a + b X (x -f y) -f c X (*2 + afy + y9) + &c. Now */» — zm = (v — z) X : 7/*"1 + t/"~" z -j- i;™-3 z.2 + &c zm~\ Also un — zn = (i; — z) X : vn~' + i;"-* z -{- z/1"3 z2 + &c z""'. Therefore — — — reduces to, and becomes = v — , „ z — i-i — c i — = A + BX(^ + y)+cX(^+^+/)+DX(^ + ^ + *y2 + y3) + &c. The law is manifest; and it is also evident that the numerator and denominator of the fraction respectively, terminate in m and n terms. Suppose then x = y; then will v = z; and our equation will become — — • or, — — = a + 2b# -4- 3ca?2 -j- 4d*3 + &c. But v" = 1 + x i therefore by multiplying we have — = a + (a + '2b)x -f- (2B -f 3c) ar2 -J- (3c + 4d) x3 -f &c. Or vm = m .7 ma . «a + 2«b , 2/?b + 3nc 2 , 3nc + 4nD 3 . 0 ~ ■'*•.'• 1+a: as x -\ x1 -\ x3 + &c. Compare this with the assumed series, to which it is similar and equal, and it will be, n\ n\ + 2»b 2«b + 3nc 0 „ — = ] ; = A ; = B ; &C. = &c. m m m m m — n m — 2n Q .*. A = -; B = — j; — A; C = ■ „ a ■ B; &C n ' 1.2.n ' 1.2. 3.« Therefore f| + »)" =: i + = » + ^^^ + ^~^^ *, + &c the law is manifest, and agrees with the common form derived from other principles. Schol. In the above investigation, it is obvious that unless m be a positive whole number, the numerator above-mentioned does not terminate: it still remains there fore to show, how to derive the series when m is a negative whole number. In this case, the expression (vm — zm) assumes this form, vm — z*, or its equal which divided by vn — zn, as before, gives zm — vm _ J_ — (v — z) X : fm"' + ? * t,» — 2» tJ™sm X (v — z) X : t>n"1 + f" VOL. XVIII. F Z — D" ^V X *n - z" ~" i>"\sm (v - z) X : ftt"x + fn'"2z + *'""'3z2 + ' ' ~ " »"z" 34 PHILOSOPHICAL TRANSACTIONS. [ANNO 17Q0\ tf— ■ + t>— °z + r"-32i -f &c. , , x wit— • — mB-"1— , . . . v.-> + v>z + v*-h>+zc. = ^hen v = z) - ;^^— T 73T' wh,ch 1S the same as the expression (— — ) before derived, with only the sign of m changed. The remainder of the process being the same as before, shows that the series is general, or extends to all cases, regard being had to the signs, a. e. d. XVII. A Description of the Anatomy of the Sea Otter, from a Dissection made Nov. 15, 1795. By E. Home, Esq., F. R. S., and Mr. Arch. Menzies. p. 385. The subjects from which the following description is taken, were procured from the natives on the west coast of America, near Queen Charlotte's Isles, by Mr. A. Menzies, surgeon in the navy, and naturalist to the expedition fitted out by go- vernment for making discoveries, under the direction of Capt. Vancouver. The sea otter is not confined to this particular situation; it was met with in the course of the voyage every where along the coast, from 30° to 62° north lat., and some- times even 100 leagues out at sea. Two sea otters were examined, both of them males ; one was a cub not old enough to leave the mother, the other appeared to be full grown. A description of the external appearances. — The large one measured 4 feet 4 inches from the nose to the extremity of the tail. The body appears a little com- pressed, and is nearly of the same thickness throughout ; its circumference is 2 feet A\ inches. The colour of this animal varies in different subjects, but in general the head and neck are grey, or of a silver colour ; the back, sides, legs, and tail, black and glossy ; in some, the longest hairs are tipped with white, which gives them a beautiful greyish cast ; the breast and belly also vary from a silver grey, to different shades of light brown. The long hairs shine with a brilliant gloss, but the short fur is exceedingly fine, soft, and thick set ; and its colour is either a light chesnut-brown, or it has a silver hue, and a beautiful silky gloss. In the cub state, the hair is a long, coarse, shaggy fur, of a brown colour, destitute of any gloss ; but as the animal grows up the fur becomes finer and more beautiful. There are 2 nipples, one on each side of the sheath of the penis, nearer to the anus than to the external orifice of the sheath. The sheath of the penis does not project beyond the skin of the neighbouring parts ; its external orifice is 7 inches from the anus, but the sheath itself extends 14- inch further on under the skin of the belly ; by which means the penis, when inclosed in it, has its point more effec- tually defended from injury. The head is somewhat compressed, and small for the size of the animal. The nose and upper lip are very muscular, and protrude about 1-J- inch beyond the gums and lower lip. The eyes are small, and placed directly over the angles of the mouth, about -£- way between the ears and the tip of the nose. The ears are nearly naked, black, slightly notched at the ends, and about 1 inch long ; they are 6 inches removed from the tip of the nose. The whiskers are in great number, they are white and strong, they arise from the upper lip on each side of the nose. There are a few weak long hairs on the eyebrows. VOL. LXXXVI.] PHILOSOPHICAL TRANSACTIONS. 35 In the upper jaw there are 6 conical incisor teeth, regularly placed ; of these the middle ones are the smallest. Two strong conical fangs, -fths of an inch long, measuring from the edge of the gums ; on each side there are 2 small obtuse pointed teeth, of which that next the fang is much the smallest ; and 1 broad molares with very irregular grinding surfaces. In the lower jaw there are 4 incisores, flatter than those in the upper ; 2 fangs, shorter than the upper ones ; and on each side 2 small teeth and 3 molares, similar in appearance to those in the upper jaw. The fore legs are short and strong, with palmated feet ; each foot has 5 toes. They are covered with a thick black fur, which has a fringe of the same colour round the edge of the sole of the foot, where the fur terminates. The hind legs, when stretched backwards, reach nearly to the end of the tail, and are well adapted for swimming, having 5 long wide-spreading palmated toes with claws, of which the innermost is the shortest ; they measure across 8 inches, and are completely covered with fur, except a small spot under the extremity of each toe. The claws are of a light colour, and channelled on the under surface ; those on the fore feet. are small, and placed so far back that they seem of little use but as a defence for the upper part of the toe ; those on the hind feet are stronger, and project beyond the toes. The tail is flat, and tapers to a sharp point ; it is covered with a thicker short fur than any other part of the animal. A description of the internal parts. — The panniculus carnosus, which lies imme- diately under the skin, is very strong, and extends over the greatest part of the body. The tongue is 4 inches long, and rounded at the end, in which there is a slight fissure, giving the tip a bifid appearance. The papillae on its surface are soft ; they are long towards the root, but less so near the tip. The os hyoides, thyroid, and cricoid cartilages are small for the size of the animal, and weak in their texture. The cricoid cartilage is not a circular ring, but made up of 2 equal parts, united anteriorly ; their lower edge at this union forms an acute angle, the 2 sides pass a little down upon the trachea as they go round it ; and the lower edge laps over the upper annular ring of the trachea. The thyroid gland is small, and divided into 2 parts. The epiglottis is short, and its edges are attached by means of a ligament to the inner side of the thyroid cartilage. The passage of the glottis is small. The rings of the trachea are circular, and disunited behind, so that their edges meet, and when pressed on, they lap over each other, being bevilled off for that purpose. Towards the bifurcation of the trachea, the space behind, which is not occupied by the carti- laginous ring, is much increased. This space is occupied by a muscle whose princi- pal fibres are transverse. The trachea is very elastic in a longitudinal direction : 7 inches of its length being readily elongated to 10^, and immediately on being left to itself it contracts to its former state. The lungs on the right side have 3 lobes, 2 large and one small azygos lobe ; the lower lobe sends a process between the pericardium and diaphragm. On the left side there are 2 lobes. The lungs were completely empty, so as readily to sink in the spirits in which they had been preserved ; the cells are very small, and so f2 36 PHILOSOPHICAL TRANSACTIONS. [ANNO 17Q6. elastic that they are difficultly expanded, and readily collapse. The anterior medi- astinum is of considerable breadth, but free from fat, consisting of nothing besides the duplicature of the pleura. In the foetus there is a very large thymus gland, convex on its external surface, and concave on the other. The heart is inclosed in a thin pericardium, is rather short, free from fat on its external surface, and rounded at the apex. The ventricles have no communication between them, but the fora- men ovale between the auricles remained open ; the passage was however so oblique, that it must have acted as a valve ; it admitted a crow quill. In the foetus it was less oblique. The structure of the heart, and the valves of the aorta and pulmo- nary artery, are the same as in other animals. There were no remains of the ca- nalis arteriosus. The aorta had nothing unusual in its appearance, but the vena cava descendens is very large ; when slit open, its breadth is 54- inches. The oeso- phagus is small for the size of the animal. The stomach is bent on itself, the pylorus being on a line with the entrance of the oesophagus, and not at a great distance from it. The cardia does not project much into the left hypochondre ; and that half of the stomach next the pylorus is much smaller than the other. The coats are thin. The internal surface is free from rugae ; the posterior portion is smooth, without any appearance of glandular structure ; the anterior portion is more vascular and villous. At the pylorus there is an oval part of the internal surface of a dark colour, and rougher or more villous than the rest of the stomach, with a determined edge ; the small end of the oval extends about 4- an inch beyond the pylorus into the duodenum ; the larger end goes some way into the stomach, and extends chiefly over the posterior surface, also a little way beyond the great arch anteriorly, covering about 4. the breadth of this part of the stomach ; it is nearly as long again as it is broad. This part is pro bably glandular ; it was only seen in the young subject, which from the smallness of its size was more perfectly preserved, and its internal parts better fitted for ana- tomical examination. At the pylorus there is the usual thickened valvular appear- ance. The stomach was entirely empty, and in a very flaccid state. The duodenum makes a considerable bend downwards on the right side before it crosses the spine, to become a loose intestine ; there is no coecum or difference of size in the intestines, they are all strung upon the mesentery till within ] 5 inches of the anus ; this part of the gut crosses the spine above the root of the mesentery, and passes down to the anus. The intestines have no valvulae conniventes ; they were 52 feet long, which is 12 times the length of the animal, In a common otter, the intestines are only 34- times the length of the animal. In a common otter 2 bags are found at the anus, but there are none in the sea otter. The mesentery is 7 inches broad, and its lower part, which may be called meso rectum, is only 5 inches in breadth. The mesentery is thin, and has a great many blood-vessels which are accompanied with fat. There are no lymphatic glands on the general membrane, but a cluster of very large ones close to the root of the mesentery. The lacteals appear a little larger than in the human subject, but the circumstance VOL. LXXXVI.] PHILOSOPHICAL TRANSACTIONS. 37 of the animal having been 2 years in spirits, was very unfavourable for their exami- nation. The omentum is a thin reticular membranous double bag, covering the whole of the intestines ; it is attached anteriorly to the great curvature of the sto- mach, but not to the duodenum ; posteriorly to the loins. The liver is made up of 5 lobes, besides the lobulus Spigelii ; 3 on the right of the falciform ligament, 2 on the left. The gall-bladder is found in the usual situ- ation, is bent in the middle upon itself, and is 6 inches long. The cystic and he- patic ducts unite at the external surface of the duodenum, forming a common canal, or ductus communis choledochus, about 14 inch long, of an oval shape, with an irregularly rugous internal surface, placed between the muscular coat and the in- ternal membrane of the intestine ; it opens into the duodenum by a projecting orifice 2-fr inches from the pylorus. The vena portarum is very large, and the pas- sage behind the ducts of the liver into the cavity of the little epiploon is also large, The pancreas is situated across the spine behind the stomach, it is not confined within the usual limits, but extends along the posterior membrane of the omentum. It is sub-divided into a number of small parts, of an oval shape, all at a certain dis- tance from each other, united by blood-vessels resembling small leaves on the branch of a shrub. The little pancreas puts on the same appearance, covering the whole meso-duodenum, which is unusually broad. The duct of the pancreas is of the ordinary size, it opens into the duodenum by a separate orifice ]i inch from the pylorus. In the common otter the pancreas has not this unusual sub-divided ap- pearance, and the duct opens by a common orifice with those of the liver into the duodenum. The receptaculum chyli is an oval bag, 4. of an inch broad, from which 2 trunks go off to form the thoracic duct, each of them about -£th of an inch in dia- meter ; these anastomose frequently in their course, so that there are always 2, sometimes 3, and even 4 trunks, running parallel to each other; the thoracic duct is 8 inches in length. The kidneys are conglomerated, 6 inches long, and 3 broad. The urinary bladder is pendulous and pyramidal, and the ureters open into it very near each other at the lower posterior part. The testicles are situated under the external skin on each side of the sheath of the penis, but have no pendulous scro- tum. They are small, flat, and oval. The tunica vaginalis communicates with the cavity of the abdomen. The cremaster muscle is very strong. The -vasa de- ferentia, as they pass behind the bladder, become a little convoluted, and open into the urethra at the caput gallinaginis. The penis, in the relaxed state, is 8 inches long, the bone 6 inches. The corpora cavernosa are small, but strong in their coats. The bone near its anterior end appears to be covered with a quantity of loose cellular substance ; this in the erected state is filled with blood, and forms a large glans 6 inches in circumference, and 4 inches long ; its anterior extremity is concave, and the end of the bone is seen in the centre. The penis, when erect, is 1 1 inches long. The erectores muscles are very strong. The globe of the eye is extremely small, and the optic nerve is small in the same proportion. Its internal 38 PHILOSOPHICAL TRANSACTIONS. [ANNO \7q6. parts were not in a state to bear examination. The articulation of the lower jaw admits of no motion forwards or laterally ; it is a simple hinge an inch long, and very narrow. The condyle of the jaw is so much inclosed in the socket as to be with difficulty disengaged. The ribs are 14 in number, 9 true, and 5 spurious. JLJ^IIL Observations on some Ancient Metallic Arms and Utensils ; with Experi- ments to determine their Composition. By George Pearson, M. D.} F. R. S. p. 395. Most of these articles, communicated by the president, Sir Joseph Banks, Bart, were found in Lincolnshire, in the bed of the river Witham, between Kirksted and Lincoln. Several of them were discovered when that river was scoured out in 1787 and 1788. The instruments were evidently made of what are commonly called brass, and iron. The brass instruments were allays of copper by tin ; and the supposed iron implements were found to be steel. It may be proper here to ob- serve, that brass is a term commonly used to denote any metallic composition the principal ingredient of which is copper ; but the most accurate writers in chemistry use the term brass, with more precision, to denote only the compound of copper and zinc ; and therefore (says Dr. P.) I shall employ it in this latter sense. SECTION I. OF THE COPPER INSTRUMENTS. § 1. Miscellaneous historical observations. — The articles belonging to this head were 7 in number ; namely, a lituus, a spear-head, a sauce-pan, a scabbard, and 3 celts. 1. The lituus. — This is represented, pi. 1, fig. 1. It is well known to have been a military musical instrument of the Romans. Several classical writers mention it, as Horace, ode i. Virg. JEn. 1. vi. v. l()2. Georg. 1. iii. v. 182. It is supposed by judicious antiquaries to have been adopted from the barbarous nations ; and that the figure of it was intended by them to resemble a snake, the principal object of their religious worship, and of the most sacred mysteries of the Druidical reli- gion. If these remarks be true, they throw new light on the crooked staff of the augurs, which the lituus much resembles. It is accurately represented among the trophies which ornament the base of Trajan's column at Rome, erected in memory of his conquest of the Dacians and Sarmatians, and covered with bas-reliefs, de- scribing the events of that war. The lituus is also found on the reverses of some Roman coins : see fig. 2. The present specimen is imperfect, a little of both ends being broken off: it is however a very valuable relic, as there is little doubt that it is the only one known to be in any cabinet at this time in Europe. It has been neatly made. The parts which appear like joints are pieces which slide over the tube for ornament, or per- haps for holding the instrument more conveniently. It had the appearance of a brazen tube, from which a great part of a blackish coating has been rubbed off. It was evidently made of a plate of hammered metal of about -^th of an inch thick. The juncture of the edges of the metal, the whole length of the tube, was pre- served by means of a solder clumsily applied, by melting it withinside the tube. VOL. LXXXVI.] PHILOSOPHICAL TRANSACTIONS. SQ This solder, which was readily melted out by a red-hot iron, was ascertained to be merely tin ; for it afforded rapidly oxyde of tin by applying nitric acid : the cold saturated solution in muriatic acid afforded Cassius' precipitate on dropping into it nitro-muriate of gold ; and it afforded no acetite of lead on digesting it in acetous acid. The black coating was easily scraped off with a knife, but the quantity of it was too small to enable me to determine whether it had been applied by art, or was the accidental effect of the mud or earth in which it had been buried for many ages. The ancients, as Pliny informs us, stained plates of one sort of copper, the aes corona- rium, with ox-gall to make it look like gold ; and the crowns and chaplets of public actors were made of copper so coloured *. It perhaps will not appear very impro- bable that the coating of the lituus was with this substance. 2. Fig. 2, represents a spear-head. In Sir Jos. Banks's collection there is a British spear-head of bone, a Norman one of iron, and a third, the article before us, of copper, which is believed with the greatest reason to be Roman workman- ship-j~. This Roman spear-head is worthy of admiration and imitation, on account of its figure, weight, and size, as an offensive weapon. It is however made of cast metal, as appears from its rough surface, figure, texture, and grain. That it is made of bad metal will be made appear hereafter. It has not been hammered, but has been cast hollow to receive a wooden shaft, and in order to be light and save the expence of metal. It is evident from its figure, that it is of the very best conceivable form for piercing, and for inflicting the largest wound at the least ex- pence of weight and bulk. 3. The sauce-pan is represented in fig. 3. From its form and the grain of its fracture, and its being one entire piece, it appears to have been made of cast metal. It is considered to be a piece of Roman workmanship. It is neatly and curiously grooved at the bottom, to admit the fire to penetrate to the contents more easily. On the handle is impressed, seemingly with a stamp, c. arat; which letters may possibly signify Caius Aratus, as the latter part of the stamp seems not to have made an impression. It appeared to have been tinned, but almost all the coating had been worn off. As it was said that it had been used by some boatmen, for some time after it had been found, it might have been tinned after it got into their possession. The art of tinning copper however was understood and practised by the Romans;}:, though it is commonly supposed to be a modern invention; so that it is not very improbable that this utensil was originally covered with tin by that people. 4. Fig. 4 represents the scabbard with a sword of iron within it, supposed to be either Danish or Saxon, being found in the Witham near the scite of Bardney * " Coronarium tenuatur in laminas, taurorumque felle rinctum, speciem auri in coronis histrionum praebet." Pliny, lib. 34, cap. 8. — ■+ An instrument is described and represented by a figure in the Archaeologia, vol. 9, fig. c, exactly like this spear-head, and it is deemed to be Roman. — J '* Stan- num illitum aeneis vasis, saporem gratiorem facit, et compescR seruginis virus." Pliny, lib. xxxiv. cap. xyii.— Orig. 40 PHILOSOPHICAL TRANSACTIONS. [ANNO \7q6. Abbey, destroyed by the Danes in 870, (Tanner's Not. Monast. p. 248.) In Strutt's korttoa 3£ngel-cynnan, where he describes the customs of our Saxon and Danish ancestors, such swords frequently occur; especially in the lives of the 2 Offas. Similar swords are also in the hands of the Danes, who are killing the abbot of Croyland on the shrine, as delineated by Dr. Stukeley, in the Phil. Trans, vol. 45, p. 5Q7- The brass scabbard possesses some degree of elegance, and much accuracy of workmanship. It appears to have been originally covered with a bright blue varnish, but the quantity was much too small for ascertaining its nature. Exactly such a sword as this is represented at the side of a Danish soldier, in pi. 2(5, vol. 1, of Strutt's work just quoted. The sword within this scabbard was destroyed by rusting, and could not be drawn out. The pommel and guard had been broken off. There was a plate of open work, about 4 inches long, laid over one side, and near the top of the scabbard ; and at the bottom, on one side, was a sort of joint; and on the other and opposite side was a bas-relief figure. The scabbard was made of hammered metal, and was perhaps about 7V of an inch thick. The next, and last 3 articles under the present head, are known to antiquaries by the name of Celts. They were probably instruments used by the ancient Britons, Gauls, or Celtae. The learned do not agree whether the celts were Roman workmanship or not: nor to what particular uses they were applied. Accordingly some persons have supposed that they were the offensive weapons of our ancestors; and others have supposed that they were both offensive military weapons, and civil in- struments; but the most probable opinion is, that they were merely domestic tools. Many of the celts are cast after the model of stone implements, which are confessedly ancient British or Celtic chopping instruments, and tools for making holes. Several of these stone implements, in Sir Jos. Banks's collection, correspond exactly with the figure and size of the celts. Great quantities of these instruments have been at different times discovered in England, as well as in Ireland, and some few in France. Sometimes they have been found in heaps, as if the owner had, and probably did throw them away by basket-fulls, as things of little value. It has been very ingeniously conjectured, that when the Romans came to Britain they found the inhabitants, especially to the northward, very nearly in the same state as that in which our late discoverers found the natives of the South Sea islands. The Britons parted with their valuable articles of food, rarities, and commerce, for metal topis made in imitation of their stone ones; but in time, finding themselves cheated by the Romans, who made these tools of bad metal, of the shape of the ancient British stone axe, as the inhabitants of Otaheite were by the use of base metals; they relinquished these tools when they became acquainted with those made of better metal, and according to the Roman patterns. Hence we see a reason for such great quantities of celts being found among the Celtic nations, and not among the Roman, excepting now and then a specimen, which may be considered as the tool or spoil of barbarian auxiliaries. 5. Fig. 5. represents a Celt, N°. 1, found on the peninsula of Ballrichen, within VOL. LXXXVI.] PHILOSOPHICAL TRANSACTIONS. 41 the precincts of a Druidical grove, or dwelling, in Ireland. The same kind of celt is described in Wright's Louthiana, b. 14, p. 7, pi. l ; and also in the Archaeologia, vol. 5, p. 113, by Dr. Lort. It weighed 1 and 4. lb. Except at the edge it was nearly -iths of an inch in thickness. It was of a blackish colour, from oxyde of the metal and dirt on its surface. 6. Fig. 6, represents the Celt, N° 2. It was found in a field, by ploughing, in Cumberland. The celt in Dr. Lort's collection which most resembles this article is delineated by fig. 11, pi. 8, p. 113, vol. 5, of the Archaeologia. The celt before us differs from that just referred to, in being grooved on both sides to receive a shaft or handle, instead of having a socket. It weighed nearly 4 lb., and was about -f-ths of an inch thick, except at the edge. Its external appearance was like that of the former celt. 7. Fig. 7, represents the Celt, N° 3. It was much smaller than the 2 former, weighing only about 5 oz., but it resembled in shape, fig. 5. In § 2. are described the external, or more obvious properties of these arms and utensils. In § 3. the specific gravities of these arms and utensils are stated, being mostly contained between the limits 8.3 and 8.9. § 4. Experiments with fire. — (a) These old instruments melted at a lower temperature than that at which copper, or even some kinds of brass melt. Though I did not (says Dr. P.) succeed in determining precisely the temperature at which each of them fuses ; it may be useful to relate the experiments made with that view. (b) lOOgrs. of each of the above 7 ancient metallic instruments, and the same quantity of copper, of pure silver, of allay of copper with 4-th of its weight of tin, of allay of copper with -rVth of its weight of tin, of allay of copper with ^th of its weight of tin, of allay of 3 parts of copper with 1 of zinc, and of gun metal, were exposed each in separate coppels, under a muffle, to the greatest de- gree of fire I could produce in the best assay furnace. A pyrometer clay piece of Wedgwood's instrument was also put into each coppel. During 40 minutes ex- posure to fire, not one of the metals melted, except the pure silver*, and the allay with zinc: nor did any of them emit visible vapour, or inflame, except the allay with zinc; nor did any matter ooze out of any of the metals. On cooling, it was found that the figure of the metals which had not been melted in the coppels was not altered, but they were changed, either totally or ex«- ternally, into scoria-like black matter. The copper allayed with zinc was found to contain a nucleus of copper within a large proportion of black scoria and white oxyde of zinc. The celt metals were changed into scoriae, including copper-like * In Wedgwood's scale it is stated,, that pure silver melts at 28°, and Swedish copper at 27°. But every part of the furnace in the above experiments might not be of the same temperature for the same space of time : and perhaps the state of cohesion and figure of the metal exposed to fire may account for the difference in the degree noted by the pyrometer in my experiment, from that stated in the scale. For I am assured, by Mr. Thos. Wedgwood, that the degree of contraction is uniform among a number of pyrometer pieces, exposed in the same part of the furnace at the same time. — -Orig. VOL. xvm. G 42 PHILOSOPHICAL TRANSACTIONS. [ANNO 17 Q6. metal. The other old metals were changed entirely into scoriae. The copper al- layed with -sVth of its weight of tin was changed into scoria containing a little copper; but the copper allayed with 4-th of tin was changed into scoria containing a little copper, seemingly allayed with a much smaller proportion of tin than before. The pyrometer pieces indicated degrees of fire, which varied between 18° and 21°. The pyrometer piece in the coppel which contained the silver, and also that in the coppel which contained the copper, denoted 20° of Wedgwood's scale, or about 3800° of Fahrenheit's scale. (c) A thin plate of each of the old metals being exposed to the flame of a candle with the blow-pipe, a blue and green flame appeared, but soon disappeared, though the fire of the candle was applied so as to keep the metal red-hot. The same kind of blue and green flame was emitted from plates of these metals when they were exposed to fire in open crucibles, before they were melted; but it disappeared in a few seconds of time, though the fire was continued to be applied to keep the metal red-hot; nor was any such flame produced when the metal was melted in open vessels, or kept stirring when in a fluid state. (d) Each of the ancient metals being melted in close vessels, was then exposed to the air, and stirred with an iron rod ; but none of them emitted any blue flame, or white vapour, as was the case when brass was so treated. The following ex- periment, to determine whether the ancient metal instruments contained any gold or silver, was made, while I was present, by Mr. Bingley, Assay Master. (e) 50 grs. of each of these metals, and as much gun metal, and also the same quantity of brass, were put into separate coppels, together with 150 grs. of lead, under the muffle of an assay furnace: 150 grs. of lead were also put alone, by way of test, into a separate coppel. The fire being kept up in the usual way, the brass emitted a blue flame, and began to melt, discharging at the same time white fumes; but soon after it was melted, the flame and white fumes disappeared. The ancient metals, and also the gun metal, afterwards melted, and without sending forth any flame, but a slight fume was seen when they were in fusion ; which was particularly evident from the coppel containing the spear-head metal. This fume was not seen to arise from the coppel which contained lead only; but the Assayers observe it from charges of lead with silver, or lead with gold and silver, when much air is admitted. ' The process being finished, nothing was left in the coppels which contained lead only, and lead and brass, except a just visible particle of silver; but in the other coppels there remained about -*- of the original quantity of the ancient metals, and of the gun metal: and therefore into each of these coppels 150 grs. of lead were again introduced. The process being performed a 2d time, every particle of metal was absorbed, excepting a just visible particle of silver in the coppels which con- tained the celt, N° 2, the metal of the scabbard, and the gun metal : but there was a much larger globule of silver in the coppel which contained the spear-head metal. As the only metal which appeared to contain more silver than the test itself VOL. LXXXVI.] PHILOSOPHICAL TRANSACTIONS. 43 was the spear-head, and as it emitted more fume than the rest, I repeated the process on this metal. The process of cupellation the 2d time, as before, caused the appearance of the white fume, and afforded a residue of silver, as before, in greater quantity than that of the test. The silver was determined in the most ac- curate way to amount to the proportion of ] 5 grs. in a Troy pound of the spear- head metal. There was no gold in this silver, for it dissolved totally in nitric acid. § 5 . Experiments with nitric acid. — (a) A polished piece of each of the ancient metals was just wetted with nitric acid. Fumes of nitrous acid arose, and the part wetted became white and corroded; as is the case when the nitric acid has been applied in this manner to the allay of copper by tin. (b) On 300 grs. of each of the above metals, in a small retort, were poured 1800gr. measures of nitric acid, purified by distillation from nitrate of silver, and of the specific gravity of 1350. The hydro-pneumatic apparatus being affixed, generally from 30 to 40 oz. measures of nitrous gaz came over in the cold, in the course of 2 to 3 days. In this time the whole, or at least the greatest part of the metal was oxydified and dissolved; there being a clear blue solution, with a copious white sediment, and sometimes a part of the undissolved metal. By means of the fire of a lamp, more gaz came over, which had been absorbed by the solution, and which also was afforded by the dissolution of the remaining metal. The whole quantity of nitrous gaz varied, with the same as well as with different metals, be- tween 60 and 85 oz. measures; but either from my own inability to observe, or from the circumstances on which this variety depended being unknown, I cannot explain the reason of such differences in the result. (c) After the solution (b) had stood several days, the clear blue liquor was de- canted, and filtrated, from the white sediment: and pure water was poured on the filter repeatedly, till what passed through was colourless, and almost tasteless. The filtrated liquid was boiled to evaporate all but about 6 oz.; and it deposited, on standing, a small quantity of white sediment. The white sediment, from the solution (b,) being dried, amounted to the fol- lowing different quantities, from 300 grs. of each of the different metals, namely, 1. The sauce-pan, exclusive of a little dirty extraneous matter, . . ..65 grs. or 21 \ per cent. 2. The spear-head, exclusive of a little dirty extraneous matter, .... 63 grs. or 21 per cent. 3. The celt, N° 3 55 grs. or 18| per cent. 4. The lituus, 54 grs. or 18 per. cent. , 5. The scabbard, 48 grs. or \6 per cent. 6. The celt, N° 1 42 grs. or 14 per cent. 7. The celt, N° 2 42 grs. or 14 per cent. (d) The decanted and filtrated liquid (c,) being duly evaporated to crystallization, was found to contain nothing but nitrate of copper, and sometimes a very minute portion of white sediment; for it threw down nothing but prussiate of copper, on adding prussiate of soda; nor was any silver deposited on immersing in it bright copper wire; nor was any precipitation occasioned by adding muriatic acid, or muriate of soda, to the concentrated blue solution. G2 44 PHILOSOPHICAL TRANSACTIONS. [ANNO I796. (e) The white sediment (c) was a light impalpably fine powder: it had a little metallic tarte: it could not be melted with borax by flame with the blow-pipe, but was diffused through that salt, and rendered it opaque. This sediment dissolved totally, except a little mere dirt, by long digestion in muriatic acid, and imme- diately in this menstruum when caloric was applied to make it boil. This solution in muriatic acid did not throw down Cassius' precipitate on adding to it nitro- muriate of gold, but afforded a white deposit exactly like that which is made on adding nitro-muriate of gold to muriate of tin, made either by boiling tin in a large proportion of muriatic acid, or by dissolving oxyde of tin, made with nitric acid, in muriatic acid. The muriatic solution of the white sediment (c,) on adding prussiate of soda, afforded a precipitate exactly like that which appears on adding prussiate of soda to muriate of tin. The white sediment (c) being mixed with tartar, on charcoal, the flame of a candle by the blow-pipe was directed upon it: by which treatment small silver-like globules were made to appear. These globules being collected, were digested in the cold, in so small a proportion of muriatic acid as could not dissolve the whole of the globules supposing them to be tin. They were gradually almost all dissolved, and nitro-muriate of gold being added, Cassius' precipitate was immediately de- posited. But the metallic globules being dissolved by boiling in a large proportion of muriatic acid, no Cassius' precipitate was produced on adding nitro-muriate of gold; nor on adding it to tin dissolved by boiling in a large quantity of mu- riatic acid. The preceding analytical observations and experiments will, on examination, perhaps be found to contain sufficient evidence to demonstrate that each of the ancient metallic instruments contains copper and tin ; and they will also perhaps be found to prove, that these metals contain no other kind of metal, or other species of matter. But, in order to ascertain the proportion of the tin to the copper more accurately than I was able to do by analysis, and also in order to confirm or inva- lidate the evidence of analysis, I made the following synthetical observations and experiments. §6. Synthetical observations and experiments. — Exper. 1. 50 grs. of tin were united by fusion with 1000 grs. of copper. The ingot of this allay of 20 parts of copper by 1 of tin, when polished, differed from the celt metals in shade of the same colour; these being much paler than this allay. It was a good deal harder, and not so tough as copper, but it was not so hard, and was more tough than the celt metals. Its fracture showed also a more open grain than the old metals, and more inclining to the peculiar red colour of copper, instead of the brown and grey, or slate colour of the ancient metals. With nitric acid it afforded, like the ancient metals, a blue liquor, and white deposit of oxyde of tin ; but in much smaller pro- portion than any of them; not being more than 7 percent. Exper. 2. 100 grs. of tin were united by fusion with 1500 grs. of copper. This allay of 15 parts of copper with 1 of tin resembled the celt metals, N° 1 and N° 2, VOL. LXXXVI.] PHILOSOPHICAL TRANSACTIONS. 45 in colour, polished surface, grain of the fracture, and brown colour of the fracture ; consequently the red colour of the copper was completely destroyed. It was not however so hard, though stronger than these celt metals; but was harder than the spear and the sauce pan. The solution of this allay with nitric acid only differed from that in the former experiment in affording a more copious white deposit, namely, 10 per cent, of it in its dried state. Eocper. 3. 100 grs. of tin were melted with 1200 grs. of copper. This allay of 12 parts of copper by one of tin could scarcely be distinguished from the last de- scribed allay in the colour of the polished surface, nor was it so much closer grained or lighter coloured in its fracture as might have been expected ; nor could I by the hammer distinguish it from that allay in point of hardness and strength. On the trial with the drill, it however betrayed a good deal more hardness. It was almost as hard as the celts, N° 1 and N° 2. With nitric acid it afforded a deposit of 1 1 per cent, of oxyde of tin. Exper. 4. 100 grs. of tin were united by fusion with 1000 grs. of copper. This allay of copper with -^ of its weight of tin was as pale coloured as the celts, N° ] andN0 2, but not nearly so pale as the celt, N°3. I could not distinguish this allay in the properties of hardness and strength from the 2 celts, N° l and N° 2, and the scabbard ; but it was harder than the spear-head and sauce-pan, though not so brittle. Its fracture showed the same kind of rather open grain, and texture, as that of the celts, N° 1 and N° 2, before they were melted, but it was not so close grained as any of the ancient metals after fusion ; and it differed from all of them in being of a lightish brown colour. The solution in nitric acid differed only from the former in affording a greater proportion of white deposit, namely, 13-^ grs. per cent. Exper. 5. 900 grs. of copper were melted with 100 grs. of tin: which allay of 9 parts of copper with 1 of tin differed very little from the former. By means of nitric acid this allay gave 17 grs. per cent, of oxyde of tin. Exper. 6. 100 grs. of tin were melted with 800 grs. of copper. This allay of 8 parts of copper with 1 of tin was also scarcely distinguishable from the 2 former allays, in colour, strength, appearance of fracture, texture, and polish. With nitric acid this allay afforded 1 84- grs. per cent, of oxyde of tin. Exper. 7. 100 grs. of tin were melted with 700grs. of copper. This allay of 7 parts of copper with 1 part of tin was evidently different from any of the former allays ; being harder, more brittle, paler coloured, the fracture showing a much finer grain, and of a grey or somewhat slate colour. The grain therefore of this allay resembles in colour that of the celt, N° 3, the lituus, the spear-head, and the scabbard. It was especially like the lituus and the celt, N° 3, in the rather bright and silvery appearance of the fracture, instead of the dull slate colour of the spear-head and sauce-pan. On trial with the hammer, and the drill, it resembled exactly the lituus in brittieness and hardness. It was a little harder and more brittle 46 PHILOSOPHICAL TRANSACTIONS. [ANNO 17 Q6, than the celt, N° 3, and of course much more so than the other ancient metals. This allay, on solution in nitric acid, yielded 20 per cent, of oxyde of tin. Exper. 8. 100 grs. of tin were melted with 600grs. of copper. This allay of 6 parts of copper with 1 of tin was harder than any of the above allays : and per- haps it was harder and more brittle than any of the ancient metals. Its fracture exhibited a still finer, brighter, silvery, and more crystallized grain than any of the preceding allays. Nitric acid separated from this allay 22 per cent, of oxyde of tin. Exper. 9. 100 grs. of tin were melted with 400 grs. of copper. This allay of 4 parts of copper with 1 of tin was about as hard and brittle as some sorts of bell- metal. Its fracture was still paler, finer grained, and silvery, than any of the pre- ceding allays. Nitric'acid separated from this allay 27 per cent, of oxyde of tin. Exper. 10. 100 grs. of tin were melted with 300 grs. of copper. This allay of 3 parts of copper with 1 of tin, was much harder than any of the preceding ones. It was also much more brittle, the fractured surface was quite smooth, and with- out almost any grain at all. It was of a silvery hue, and resembled much an ingot of a melted bell ; excepting that it was finer grained, and of a duller colour. Exper. 11. 100 grs. of tin were melted with 200 grs. of copper. This allay of 2 parts of copper with 1 of tin, was as brittle almost as glass. The fracture showed no grain at all, being quite smooth. Its colour was more like that of silver than any other metal. Exper. 1 2. The metal of which what are called brass guns are made, does not in general contain a grain of zinc. They are made of an allay of about 10 to 12 or 13 parts of copper, with one part of tin. I found that the shavings of 1 of these guns melted much more readily than copper. The ingot was not so hard, but tougher than any of the above ancient metals. It possessed nearly the same hardness and strength as the allay, in experiment 3, of 12 parts of copper by 1 of tin. The colour of the polished surface, and the grain and colour of the fractured surface, resembled pretty exactly that allay. Of course this gun metal is only a little less hard and brittle than the celts, N° 1 and N° 2, but it resembles them very exactly in the colour and texture of the grain. This gun metal afforded nearly 13 per cent, of oxyde of tin, by means of nitric acid. Exper. 13. 20 grs. of tin and 10 grs. of zinc were melted with 800 grs. of copper. This allay of 80 parts of copper with 2 parts of tin, and 1 part of zinc, was a metal which had a very different aspect when polished, as well as when frac- tured, from either copper, or any of the above allays, or any of the ancient me- tals. For it had a rich yellowish or golden hue, and was nearly as tough, but a little harder than copper. Exper. 14. 20 grs. of zinc were united by fusion with 800 grs. of copper. This allay of 40 parts of copper with 1 part of zinc, was of a yellowish golden hue, and of course was very different in its external appearance from the allays of copper by tin. Like the allay of experiments 1st and 13th, it was too soft, and, as the VOL. LXXXVI.] PHILOSOPHICAL TRANSACTIONS. 47 artists term it, clingy, to receive the impression of lines, figures, and letters, or for instruments in which holes are to be drilled. The solution of this allay in nitric acid was blue, like those of the preceding allays and old metals, but there was no white deposit. Observation. — This is the proper place to observe that all the above allays, and the gun metal, melted at a lower temperature than copper does ; and, as far as I could determine, the temperature of fusion decreases as the proportion of tin in- creases. The next experiments were made not only to satisfy myself, that if iron had been an ingredient in the ancient metals, it must have been made appear by the test employed ; but also to determine the question made by some chemists, whether copper can be allayed by iron ; and to show, as others have asserted, the allays of copper by iron, which were employed by the ancients. From the writings of many able chemists I was inclined to suppose, that a malleable uniform metal could not be composed of copper and iron, without the aid of an intermede. I therefore, in the first place, used tin as the intermede. Some of these experiments next to be related may not be found immediately relative, but as they occurred in the course of investigation, and as I believe few experiments of the same kind have been published, perhaps they will be found useful. Exper. 15. 2000 grs. of tin were melted with ]000 grs. of steel,* by keeping the 2 metals in a close crucible exposed to a pretty fierce fire of a melting furnace. An allay was produced of a uniform metallic mass, of the colour of pewter, of a very open grain, but uniform texture; which was as brittle, and not harder than certain kinds of old bad pewter. Exper. 16. 1800 grs. of tin were melted with 600grs. of steel. This allay of 3 parts of tin with 1 of steel was perfectly similar to the last allay of 2 parts of tin with 1 of steel, excepting that the allay of this experiment was not so hard, and was less brittle. Having thus prepared the steel for union with copper, by the me- dium of tin, I added to it copper. Exper. 17. 600 grs. of the allay of exper. 15 were melted with 2400 grs. of copper. This allay of 12 parts of copper with 2 parts of tin, and 1 part of steel, resembled exactly the allay of 6 parts of copper with 1 of tin, in exper. 8, in the colour and grain of the fracture ; in its polish, hardness, and brittleness. Its frac- ture was of course of a slate-coloured hue, or dark grey, somewhat crystallized and silvery. The fracture being inspected with a lens, the grain appeared finer or shorter than that of the allay of 6 parts of copper with 1 of tin. The solution of this metal in nitric acid produced nitrous gaz, a blue solution, and a white deposit; as occurred in the dissolution of the ancient metals, § 5, p. 43, and of the allays of copper with tin, p. 44 — 4Q; but the result of the examination of this blue solution and white deposit was different from that of the ancient metals, and satisfied my mind completely, that if those metals had contained iron, it must have been detected. * The steel employed was part of a file. Steel was preferred to iron, because it is fusible, but iron is not.— Orig. 48 PHILOSOPHICAL TRANSACTIONS. [ANNO 179^5. (a) The blue solution of this experiment being boiled, to carry off redundant acid, and evaporate about 4-ths of its water, prussiate of soda was added. A red- dish-brown precipitation ensued, which resembled exactly that produced by adding this test to nitrate of copper. (b) The white deposit of this experiment having been well edulcorated by pure water was wholly dissolved in muriatic acid. This solution differed from that of all the white deposits of the preceding experiments, in being of a reddish-brown co- lour, like dilute solution of muriate of iron, and especially in affording a copious precipitation of prussiate of iron by prussiate of soda. With nitro-muriate of gold however, this solution only produced a slight grey precipitation, as in the former experiments. Exper. 18. 1000 grs. of the allay of experiment 15 were melted with 2000 grs. of copper. This allay of about 7 parts of copper with 2 parts of tin, and 1 part of steel, was an extremely hard metal, much harder than that of the last experi- ment ; and it was very strong, but scarcely malleable. It took a beautiful polish, of a silvery colour. It was of a perfectly homogeneous texture. The grain of its fracture was extremely fine and uniform, and of a grey colour. Exper. 19. 2000 grs. of copper were melted with 200 grs. of steel, in a close vessel, by keeping them exposed to a fierce fire in a wind-furnace for about 20 mi- nutes. This allay of 10 parts of copper with 1 part of steel, was of a copper co- lour. The grain of its fracture was coarse, like that of copper. It was harder than copper, and less tough, but quite malleable. It was about as hard as the allay of 20 parts of copper by 1 of tin, and consequently was not nearly so hard as the softest of the ancient metals. Exper. 20. 1000 grs. of copper with 500 grs. of a small round steel file were exposed to fire, as stated in the last experiment. On opening the crucible, part of the steel only was found to have been melted and united to the copper ; but the other part of the steel which retained its form, was thoroughly impregnated or pe- netrated by copper ; so that on breaking the part which had not been melted, and which was very brittle and porous, it was in appearance imperfectly metallized cop- per. The part of the allay which had been melted was not different from the allay of the last experiment, except that it was a little harder ; being thought to be about as hard as brass. Then follows a statement of the specific gravities of the different allays above de- scribed, which run variously between the limits 7.2 and 9. ^ 7- Conclusions and remarks. — 1. The first conclusion, from the preceding ob- servations and experiments is, that the ancient metal instruments examined consist principally of copper, as appears ; 1st, from their external and obvious properties ; particularly their colour, taste, malleability, and specific gravity : 2dly, from the whole of the metals, except a small deposit, yielding nitrate of copper with nitric acid : 3dly, from the synthetic experiments. 2. 1 conclude that these metal instruments contain tin ; which metal was made VOL. LXXXVI.] PHILOSOPHICAL TRANSACTIONS. 4Q appear, by the experiments on the white deposit afforded on dissolution in nitric acid, § 5 : and which also was made appear by the synthetic experiments, § 6. 3. The 3d conclusion is, that these metallic instruments consist of metal only, or at least of nothing else which can be detected by ordinary known modes of ana- lysis : for they are all malleable, and uniform in their texture ; which properties metals do not possess when they are mixed by fusion with extraneous substances hitherto discovered by analysis ; except carbon in several metals, and siderite in iron only. 4. The 4th conclusion is, that these ancient instruments contain none of the metals but copper and tin : for, 1 . They do not contain gold, silver, or platina, ex- cepting silver in the spear-head, as appears from the experiment of cupellation, § A, (e). — 2. They do not contain lead : for that would have oozed out in the experi- ments of fusion and oxydation ; and would have appeared in the grain of the frac- tures ; as well as on adding muriate of soda, and muriatic acid, to the concentrated nitrate solution, fy 5, (d). — 3. They do not contain iron : for that would have been shown by the prussiateof soda, § 5, (d) ; as was proved by the synthetical experi- ment, §6, exper. 17, (b). — 4. They do not contain zinc: for that would have been shown by the blue flame and white flowers in exper. § 4, (c) (d) ; as well as by the yellow colour of the grain of the fracture, which was shown by the synthe- tical experiments, §6, exper. 13 and 14. 5. Bismuth would have appeared on diluting the nitrate solution, § 5, (d). — 6. Manganese would have been seen on concentrating by evaporation the nitrate solution, § 5, (c) (d). — 7. Arsenic would have manifested itself by the brittleness and whiteness of the metals ; by the smell and visible vapour on exposure to fire and air ; and on examining the solution, § 5, (d), and the white deposit, § 5, (e). — 8. Antimony would have produced more brittleness than these ancient metals possessed : a white vapour would have appeared on examining the white sediment with the blow-pipe, § 5, (e) : as well as in the experiments in the assay-furnace, § 4, (b) (e) ; and a white precipitate would have fallen on diluting the muriatic solution of the white deposit from the nitrate solution, § 5, (e). — 9. Cobalt would have been detected by the prussiate of soda ; and by the colour of the oxyde, in the experiment in the assay furnace, § 4, (b) ; and it would have given brittleness to the ancient metal instruments. — 10. It is not at all probable that nickel was pre- sent ; but if it had been an ingredient, it most likely would have been betrayed by its greenish oxyde in the experiment, §4, (b). — 11. Molybdaena, and quicksilver may be mentioned for the sake of order, but it is utterly unreasonable to suppose them to be present, either naturally or by art ; and evident appearances, or at least traces of them, must have occurred in the preceding experiments. As for the sub- stances called tungsten, uranite, menackanite, and titanite *, we have not yet had sufficient evidence to prove their being peculiar metals ; but from the properties which have been observed to belong to them, it is quite inconsistent with the pre- * A new metal, named Titanium, lately announced in the German Journals, — Orig. VOL. XVIII. H 50 PHILOSOPHICAL TRANSACTIONS. [ANNO 17Q6. ceding experiments and observations to suppose them to exist in the ancient metal instruments. It will be proper also to remark, that the only species of metals known till within the last 2 or 3 centuries, were gold, silver, quicksilver, iron, cop- per, lead, and tin. The oxydes of several of the brittle metals were known indeed to the Hebrews, Greeks, and Romans, and perhaps to several barbarous nations of great antiquity ; but not one of them was used as an allay, except the oxyde of zinc to compose artificial orichalcum. It appears that the metal of the spear-head contained silver ; but though the pre- sence of it was proved by a repeated decisive experiment, § 4, (e), the proportion of it was too small to alter sensibly the properties of the allay of copper with tin, and could not answer any useful purpose in such a compound. I therefore believe that the silver in this instance was not purposely added ; but was an accidental or natural ingredient of the copper, used for making the metal of this spear-head. The Bishop of Llandaff made a few experiments on a celt, from which his lordship concludes that it seemed to contain zinc: for it emitted a blue flame, and a thick white smoke, on the first exposure of a piece to fire ; but no such appearances were seen on the 2d exposure of the same piece to fire. Every person will readily give credit for the observations being accurately made ; nor would I even refuse to admit the conclusion, that the celt examined by his lordship did contain zinc ; but it is also just to observe, that a piece of copper, or of allay of copper, with tin, being exposed to fire in an open vessel, emits frequently a blue flame on a first, but not on a 2d exposure to fire soon after the first, § 4, (c) ; and if much air be admitted to the allay of copper with tin in fusion, a white smoke will also sometimes be seen ; as was observed in the preceding experiment, § 4, (e). I suspect that the blue flame from copper when first ignited, and which ceases on fusion, is produced by the inflammation of a little of the copper already com- bined with oxygen ; for some oxydes of copper are so combustible, that if a small part of a given mass of them be ignited, the ignition will spread rapidly throughout the whole mass. Most probably celts were originally chopping tools, as we have shown in a former part of this paper, and therefore the addition of zinc to the allay of copper with tin would answer no useful purpose. 5. The 5th conclusion relates to the proportion of the copper and the tin to each other, in the ancient metals. I endeavoured to estimate the proportion of tin, by comparing the quantities of oxyde of tin obtained from the ancient metals, with the quantities of oxyde of tin obtained by the same means from allays of copper with known proportions of tin. It appears from the analysis of the allays of cop- per by tin, that the oxyde of tin afforded by the nitric acid solution is in the propor- tion of about 150 parts from every 100 parts of the metal tin, § 6, ex per. 1st — 9th. According to this datum the proportion of tin in the old metals is in the following proportions, or nearly so. 1. The sauce-pan contains of tin a little more than 14 per cent. ; that is about 1 part of tin and 6 of copper, — 2. The spear- head contains 14 per cent of tin ; that is, somewhat less than 1 part of tin and 6* VOL. LXXXVI.] PHILOSOPHICAL TRANSACTIONS. 51 of copper. — 3. The celt, N° 3, a little more than 12 per cent, of tin; that is, about 1 part of tin, and 74- parts of copper. — 4. The lituus, nearly the same pro- portions of tin and copper as the celt, N° 3. — 5. The scabbard, a little more than 10 per cent, of tin ; that is, about 1 of tin and Q parts of copper. — 6. The celt, N° 1, a little more of tin than Q per cent. ; that is, about 1 of tin and 10 parts of copper. — 7- The celt, N°2, the same proportions of tin and copper, as in the celt, N° 1. 6. The last 2 conclusions are confirmed by the exact correspondence between the ancient metals and the allays of copper by tin, in external and obvious proper- ties, § 2 and § 6 ; in specific gravities, § 3 ; and in chemical properties, § 5 and ^ 6. Allays of 5 to 18 parts of copper with 1 part of tin can generally be distin- guished from such allays with the addition of a very small proportion of the other metals ; by the colour of their polish, the colour and texture of their grain, their strength, their hardness, their malleability, and specific gravities ; without the aid of chemical analysis. It is worthy of remark, that these allays of copper with tin are evidently different, in their colour and grain, from such allays with the addition of even V-otn of their weight of zinc, exper. 13th ; and also from copper allayed by ■^Vth of its weight of zinc, exper. 14th. The similarity of the properties of the ancient metals, and of the allays of 6 to 1 2 parts of copper with 1 of tin, is very evident. But with smaller proportions of tin we find the allays are softer, and the grain of their fractures more open than the ancient metals, experiment 1 — 4. ; and with larger proportions of tin we find the allays harder, more brittle, paler, and closer in texture than the an- cient metals, experiments — 11. It is right, however to remark, that the pro- perty of hardness of the allays of copper by tin is, caet. pan as the proportion of tin, or nearly so; which is not the case with some of the ancient metals; for the spear-head and sauce -pan contain rather more tin than an equal quantity of the li- tuus, § 5, (c), which is much harder than they, § 2. (c) ; and the spear-head and sauce-pan are nearly as soft as the celts, N° 1 and N° 2, § 2, (c), which contain the smallest proportion of tin of any of the old metals, § 5, (c). The grain also of the fractures of the spear-head and sauce-pan, before melting, is much coarser, or open, than those of the other ancient metals which contain a smaller proportion of tin, § 2, (b) : but it appears from the synthetic experiments that the grain becomes finer as the proportion of tin is increased, § 6, exper. 1 — 12. To account for these inconsistencies I must remark, that a minute quantity of extraneous unmetallic matter may be contained in metals ; so minute indeed as to elude the most rigorous analysis, or at least not to be discoverable by the ordi- nary modes of examination ; and which also may not render the metal at all unfit for most of the uses to which it is applied. For instance, good malleable iron may contain carbon, and even phosphate of iron or siderite ; and metals in general may contain a very small proportion of oxygen, and yet be as useful as the purest metals. The best English copper is accounted less tough and ductile than Swedish copper. The purest English tin crackles when it is bent or chewed, but pure h 2 52 PHILOSOPHICAL TRANSACTIONS. [ANNO 17g6. Malacca tin has not this property. These differences of properties most probably depend on some extraneous matter ; but in so small a proportion as to have hitherto eluded the research of analysis. In the case before us, it is probable that a very minute proportion of extraneous matter was present in the spear-head and sauce-pan, especially as they were made of cast metal ; which might be less hard, and less compact in texture, than an allay of pure metals, containing a smaller proportion of tin to the copper, and yet the allay might be less brittle than the cast metal. This extraneous matter may be oxygen, or sulphur, or earth, though in an imperceptible quantity, introduced during the fusion. The lituus is harder, and not more brittle than the spear-head and sauce-pan ; though it contains less tin. It was made of a plate of metal which had been much hammered, and must therefore either originally have been made of purer metal than the spear-head and sauce-pan, or have been rendered purer by hammering. Perhaps metals in general are rendered purer, more uniform in tex- ture, and more dense, by re-melting, than they were immediately after casting from the ore ; or in the case of steel immediately after cementation ; or in the case of allays after the fusion by which the union was effected. Accordingly, cast iron is rendered less brittle by repeated fusion ; Mr. Huntsman's cast steel is made by merely re-melting steel which had been manufactured by cementation ; and Mr. Mudge's speculum metal, an allay of copper by tin, was not uniform and suffi- ciently compact till it was re-melted. The specific gravity of the sauce-pan, and spear-head, was particularly increased by fusion, § 3, 2, 3 ; and their texture was rendered more uniform and compact, § 2. The specific gravities of the ancient metals correspond, as nearly as should be expected, with their composition found by analysis ; and agree sufficiently with the synthetic experiments, § 3 and § 6. I did not find that the specific gravity of the same metal, under known circumstances alike, was so nearly the same in all cases as is stated by most writers. In the preceding experiments, different parts of the same ingot varied more than is commonly supposed in point of specific gravity. The specific gravities of the ancient metals, after melting, varied between 8.5 and 8.8, or nearly so; and the specific gravities of the allays of 3 to 20 parts of copper with 1 of tin varied between about 8.5 and 8.9. These great specific gravities seem surprizing, because that of tin is only about 7-2, and of copper ingot about 8.420. But of all metallic combinations that of copper with tin produces perhaps the greatest increase of density. Aristotle made this observation long since *, and the fact is familiarly known to manufacturers of bell-metal. But it does not ap- pear that the increase of specific gravity is so great as it is stated by Glauber. According to him, if 2 balls of copper and 2 bails of tin of the same dimensions be melted together, the compound will afford scarcely 3 balls of the same dimen- sions as each of the 4 balls ; and yet the 3 balls will weigh as much as the 4 balls. — " Funde praedictos globulos in unum iterum effunde mixturam liquefac- tam in typum globulorum primorum, et non prodibunt iv sed vix iii numero glo- * Aristotle, IIEFI teneseqs kai 4>©OPAS to a. K«p. ♦.— Orig. VOL. LXXXVI.] PHILOSOPHICAL TRANSACTIONS. 53 buli, pondere iv globulorum reservato.1' — Glauber, de Furnis, pars iv. p. 67. 8vo. 1651. The specific gravity of the allays of copper by tin, and the following experiment, show that the contraction in the dimensions of these 2 metals on combination, can- not be so great as stated by Glauber. I made 2 ingots of tin and 2 of copper, of nearly the same figure and dimensions. The specific gravity of the tin was 7*233, and that of the copper was 8.594. The absolute weight of these 4 ingots was 1730 grs. On combination by fusion, the compound afforded 3 ingots and 4- of an in- got, of the same dimensions as the orginal ones; but those weighed only 1640 grs.; QO grs. being wasted and adhered to the melting pot. The specific gravity of one ingot of this metallic combination was 8.340; and of another, 8.4. Consequently, after making the most reasonable allowance for the errors of the experiment, the contraction could not be -i-th of the sum of the bulks of the metals before fusion, according to Glauber ; but it might be about -Lth. 7- I next observe, that the proportions of tin found in the ancient metals consist with the uses for which they were made. The principal uses of the allay of copper by tin are, to render copper less oxydable by water, or atmospheric air ; to give hardness ; to render it sonorous ; to render it more fusible ; to produce a close tex- ture and whiteness for reflecting light ; and to render copper less tough and clingy, or as the workmen say claggy. Copper allayed with one of the smaller proportions of tin by manufacturers, is metal of which guns or cannon, improperly called brass guns, are made. Different proportions of these 2 metals are used at different manufactories ; but I believe that this gun metal seldom contains less than 1 part of tin to ] 2 of copper, nor more than I part of tin to 9 of copper. Here as much strength, as is consistent with the preservation of the figure of the instrument during its use, is required: and if more tin were added, the gun would be liable to be fractured by the explosion ; and if less were added, it would be liable to be bent. Copper allayed with a somewhat larger proportion of tin than in gun metal in general, affords a metal sufficiently hard and strong for chopping tools, for many useful purposes. Of such proportions, namely, about 8 or 9 parts of copper and 1 part of tin, there is very little doubt all the ancient nations, who were acquainted with the allays of copper by tin, generally made their axes, hatchets, spades, chizzels, anvils, hammers, &c. These metals, united in these proportions, I believe would afford the best substitute known at this day for the instruments just mentioned, now commonly made of steel or iron. Accordingly, before the art of manufactur- ing malleable iron from cast iron was known at all, or at least practised extensively, that is, till within these last 4 or 500 years, the allays of copper by tin must have been very generally employed. The celts may be considered as specimens of the kind of metal tools in general use before the art of manufacturing iron in the man- ner just mentioned was discovered : for, as hath been remarked in a former part of this paper, the celts seem to have been generally neither more nor less than metal 54 PHILOSOPHICAL TRANSACTIONS. [ANNO 17 QQ, heads of hatchets, and axes, or other chopping tools. And it is no small confirma- tion of this opinion, that by analysis and synthesis we have found those metals to contain, in perhaps most instances, the proportions of tin which renders them most fit for the uses to which they were applied. This proportion being considered to be about 1 part of tin to 9 parts of copper. Copper allayed with a larger proportion of tin than is generally contained in celt metal ; that is, with £th or -fth of its weight of tin, is fitter for cutting instru- ments, and piercing, boring, and drilling tools than celt metal ; because it is harder, takes a finer edge, and yet is sufficiently strong on most occasions ; nor do we pos- sess at this day any metal, that I know, which is so fit for knives, swords, daggers, spears, drills, &c. as this allay, except iron and steel. The spear-head contains tin in the very proportion here mentioned ; and if the metals had been pure, it would perhaps not have been possible to have made this instrument of any other metals, which were so proper, and at so small an expence. The sauce-pan also was made of allay of copper by tin in the proportions last mentioned ; but as this instrument is sufficiently hard with less or without any tin, there seems to be no use from the addition of it. We may conjecture indeed, that as the sauce-pan was made of cast metal, the tin was made for the purpose of rendering the copper more fusible, and thus also for more easily casting forms of it. Perhaps also the tin was added to render the copper less readily oxydable, and for the colour of this composition. Copper united with the proportions of tin last mentioned is very sonorous ; but it is rendered much more so by still larger proportions of tin. I apprehend the sonorous property increases as the proportion of tin is increased, within certain limits ; provided the allay possess sufficient strength not to be fractured by the ne- cessary impulse. But as the brittleness increases with the increased proportion of tin, I believe not more than 1 part of tin is added to 3 parts of copper to compose the most sonorous metal which is manufactured, namely, bell-metal.* But this allay is too brittle to be beat out into a plate for making a trumpet; and accordingly the lituus, which has been made of hammered metal, contains only about ] part of tin and 7± parts of copper. Copper is united with tin for the purpose merely of becoming more fusible, and of continuing longer fluid, or cooling more slowly while passing from the melted, or fluid state, to the solid state. Such metal is used for making statues, and casts of figures in general, and is called statuary metal,-}- and sometimes bronze. The proportions of the 2 metals are various ; probably according to the colour proposed, and the size and figure of the cast ; as well as on account of the price of the metals. * The proportion of tin varies in bell-metal from -J. to -^th of the weight of the copper ; according to the sound required, the size of the bell, and the impulse to be given. — Orig. •f The Greeks and Romans consumed vast quantities of copper in casts of figures. They added not only tin but lead to the copper. The proportions given by Pliny are 1 part of a mixture of equal quanti- ties of lead and tin to 15 parts of copper. The use of the lead I do not understand, if it was not to save expence. — Orig. VOL. LXXXVI.] PHILOSOPHICAL TRANSACTIONS. 55 A small proportion of zinc is sometimes added to allays of copper by tin ; on some occasions, on account of colour, on others perhaps to render the copper still less oxydable and more fusible ; and on other occasions, as I have found on inquiry, it is added from erroneous theory, or mere caprice. No one could tell me the use of zinc, which in some manufactories is added, in making gun metal. Tin might be used also to render copper less clingy, or more brittle, for the purpose of writing on it, or marking it with lines and figures, as on mathematical instruments : but the allay with zinc is now preferred for these purposes, as I sup- pose on account ©f its being less hard than allays with tin, and yet sufficiently brittle; on account also of its golden colour ; and also on account of its being still more difficultly oxydable by air and water. The scabbard metal contained a rather larger proportion of tin than the celts, N° 1 and N° 1 ; namely, being -^ th of its weight. Copper allayed by zinc would have been sufficiently hard and strong, and on other accounts preferable to the allay of copper with tin. This is however one proof of the extensive use of this last com- position among the ancients. The art of allaying copper with an earth-like substance; which, within a little more than the last 50 years only, we have learned was an ore of a metal, namely, zinc; was known perhaps in the time of Aristotle, and certainly of Pliny ; for the latter informs us, that this composition resembles orichalcum ; and after his time it was called orichalcum. Thus the native and factitious orichalcum were confounded. The ancients do not appear to have used the allay of copper by zinc, except for mere ornaments, to resemble gold. It is much more extensively employed by the moderns, and the allay of copper with tin is less extensively used : 1st, because the former is cheaper than the allay of copper with tin ; 2dly, because it is now gene- rally understood that it preserves its colour longer ; 3dly, because it is easier to work it into various forms, and especially for philosophical instruments ; few of which were probably made by the ancients. The composition in common use, which contains the greatest proportion of tin, is called speculum metal The requisites of this metal are compactness, uniformity of texture, whiteness, sufficient strength to prevent its cracking in cooling, and to bear polishing without breaking. Mr. Mudge found the whole of these properties attainable in the greatest degree, by a little less than 1 part of tin with 1 parts of copper. But for very large instruments, such as the 40-feet telescope of Dr. Herschel, the proportion of tin must be less than in small instruments, on account of the property of brittleness. The compound of equal weights of copper and tin is so brittle, that it is not easy to conceive to what useful purpose it can be applied. The allays of tin with copper, by which I mean those compounds of copper and tin in which the tin is in greater quantity than the copper, I believe, have not been examined. It is said, indeed, that tin allayed with a very small proportion of cop- per has been employed for tinning, to save much of the expence of tin; for a much thinner coat of this compound can be spread than of tin. 56 PHILOSOPHICAL TRANSACTIONS. [ANNO 179& 8. The next conclusion is founded on the experiments of the allays of copper with steel. It appears that copper may be united to steel without the intermede of any other metal ; for a perfectly homogeneous compound was produced by melting 10 parts of copper with 1 of steel, § 6, exper. 19. As this allay was not harder than that of copper with -^th of its weight of tin, and as it did not appear that a compact and uniform malleable metal could be composed of 2 parts of steel with 2 parts of copper, fy 6, exper 20, I thought it unnecessary, to make any more experi- ments with different proportions of copper and steel. For, 1st, granting that the allays of copper by steel are as hard, strong, and malleable as those of copper by tin, it is utterly improbable that the ancients should have used steel to harden cop- per; on account of the great scarcity and high price of steel comparatively with tin; and also on account of the difficulty of uniting copper with steel, and the facility of uniting copper with tin. 2dly. It appears that no allays of copper by steel can be made, which possess the hardness, strength, and malleability required ; but which required properties we obtain by combinations of copper with tin, and with which most indubitably the ancients were well acquainted. Count Caylus has indeed told us, that the ancients had 2 methods of hardening copper ; namely, by cementation, and by allaying it with iron. The first method he has not explained; nor is any method known of hardening copper without addition, except by hammering it; which it is well under- stood cannot produce the required hardness. As to the other method by allaying with iron, I think myself warranted in refusing the Count's single vague evidence; and in admitting the evidence of other plainly decisive experiments ; which consist also with reasoning and analogy. Philological, and antiquarian writers, in giving an account of the copper arms and utensils of the ancients, (as they found them much harder than copper, and that they were used for purposes to which copper would have been quite unfit ; and as they saw that the ancients commonly used copper on most of those occasions in which we now use iron or steel) ; were led to imagine, that in ancient times there was an art understood of tempering copper, which had been subsequently lost.* If, instead of feigning such an hypothesis, these writers had examined by analysis the ancient implements which fell under their observation, I cannot doubt that they would have unravelled the mystery. Count Caylus himself had a glorious oppor- tunity of ascertaining the composition of ancient copper instruments, when the 7 swords and hollow wheel were found at Genzac in 1751. If he had made but 2 adequate experiments, one to detect iron, and the other to detect tin, he would * u It appears, says Dr. lorl," in his paper on celts, " that the ancients had an art of tempering and hardening brass to a greater degree than is done at present, or perhaps than is necessary to be done." — Archacol. vol 5, p. 187. With reluctance I must observe, that such an experienced inquirer as Dr. Priestley falls into the error of antiquaries, in asserting, that the ancients had a method, with which we axe not well acquainted, of giving copper a considerable degree of hardness, so that a sword might be made of it with a pretty good edge. But Pauw tells us, that the Americans were in possession of the secret of giving a temper to copper equal to steel. — Orig. VOL. LXXXVI.] PHILOSOPHICAL TRANSACTIONS. 57 have had a much better foundation for reasoning than that of a mere hypothesis, however ingenious and learned.* There is not the least reason to suppose that the ancients added iron or steel to increase the hardness or strength of the allay of copper by tin ; nor does it appear from the experiments with this mixture, exper. 17, and 18, that any advantage is to be expected from this addition ; at least not for cutting instruments. I cannot confirm the opinion above delivered, that the common metal of the ancients for cutting instruments was the allay of copper with tin, by the experiments of other persons, excepting those of Mr. Dize, in the Journal de Physique for 1790, p. 272. He had only 25 grs. of an ancient dagger to operate on. This small quantity how- ever afforded tin and copper, as appeared on dissolution in nitric acid. But Mr. Dize made several analytical experiments on 8 different sorts of coins, Greek, Ro- man, and Gallic. It appears from these experiments that these coins contained from .fV of a grain to 24-i- grs. of tin in 100 grs. of each of the old metals. And it appears that these coins contained no other metal but copper and tin. From the preceding experiments and observations we learn,that tin was infinitely more valuable to the ancients than it is to the moderns : without this metal, it is not easy to conceive how they could have carried on the practice, and invented the greater part of the useful arts. Tin was even of more importance to the ancients, than steel and iron are to the moderns; because allays of copper by tin would afford better substitutes for steel and iron, than any substitutes which the ancients, in all probability, could procure for allays of copper by tin. We see also the importance of Britain, in times more remote probably than those of which we have any record or tradition ; being probably the only country that furnished the metal so necessary to the progress of civilization. If Mr. Locke had been acquainted with the pro- perties of the allays of copper by tin, and of their extensive use in highly advanced states of civilization among the ancients, he would have known that iron was not the only metal, by the use of which we are in possession of the useful arts, nor con- sequently is it " past doubt, that were the use of iron lost among us, we should in a few ages be unavoidably reduced to the wants and ignorance of the ancient savage Americans." In the barbarous state of its inhabitants, this island was known to the civilized nations of Europe, Asia, and Africa ; and denominated in 2 of the most ancient languages, namely, the Phoenician and Greek, by terms which de- note, the land of tin ; for such, according to Bochart, is the import of Britain, a corruption of Barat-Anac, or Bratanac ; and there is no doubt of the meaning of the Greek word Cassiterides. I do not mean by these observation to represent, as authors in general have done, that the ancients were not acquainted with the art of manufacturing iron, or steel, till long after the common use of copper, or that they did not know the superior properties of iron and steel : on the contrary, if this were the proper place, I could show that iron, or at least steel, was manufactured, and its useful properties under- * See Recueil d'Antiq. Egypt. Etrusques, Grequcs et Romanies, torn. 1. 4to, 176*1. VOL, XVIII. I 58 PHILOSOPHICAL TRANSACTIONS. [ANNO 17Q6. stood, as enrly as copper was known. But steel was got anciently from those ores only which yield it in a malleable state ; as it is probably obtained at this day in India, and called wootz ; and as it is also obtained in the northern Circars, and likewise by the Hottentots. As steel was the only state of iron anciently manufac- tured, it was too scarce, and much too dear for general use; and hence the exten- sive use of allays of copper by tin, the best substitutes for the malleable state of iron and steel. SECTION II. OP THE STEEL ARMS. § 1. A few miscellaneous observations. — Of the ancient steel or iron arms and utensils in Sir Jos. Banks's collection, 4 articles only were selected for examination. One of these was the steel sword within the copper scabbard, described in sect. 1, $1,4. and represented by fig. 4. 1. A sword, fig. 8. Of a number of these weapons in the collection, this was the smallest. The great difference in their size and weight, it is observed, was probably intended to give every man, according to his strength and mode of fight- ing, an opportunity of suiting himself. The figure of the blade is particular, and seems very well contrived. The hollow in the middle of each side does not extend more than -f-ds from the guard to the point ; and terminates in a ridge, which must give great support and strength to the cutting part The pommel and guard had been tinned, and part of the tin coating still remains on them. This weapon there- fore affords a specimen of the mode of tinning iron practised by the ancients. The blade seems to have been varnished by black matter, which remains very brilliant and smooth. On one side is the inscription + benvenutus +, and on the other + me pecit -f-, perfectly legible. From the crosses, we may conclude that the maker was a Christian ; and from the name, that he was an Italian. The writing is in mixed characters, but it is probable that the artist exercised his trade of a sword cutler in the northern parts of Europe. We cannot however determine whether it be Danish, or Saxon. It was found in the river Witham, with a large quantity of other arms, in the neighbourhood of the scite of Bardney Abbey ; and was brought up by an eel-spear, by a man who was fishing in that river, near Kirk- sted Wath, in 1788. 2. An axe. Its form is evident from the fig. 9. It was snipt a good deal, and several holes were worn in the middle, otherwise it was in a state of good preserva- tion. It was found, with other axes, chopping instruments, and carpenters' tools, in the river Witham, in 1787 and 1788. This axe perfectly resembles that carried by the lictors in their fasces, in basso-relievos. Its form induces one to suppose, or indeed to believe, that it was made for parade rather than use; its edge being very thin, and immediately above it the blade being thicker; but behind the thick part, exactly where the strength of an axe ought to be placed, it is thinner than in any other part. It was therefore not well calculated for chopping. The weight of this axe was somewhat more than 1^- lb. Its length from eye to edge was 7 inches, and the breadth was about 6 inches. 3. A dagger; its form is represented by fig. 11. It was made with great inge- VOL. LXXXVI.] PHILOSOPHICAL TRANSACTIONS. 5g nuity and skill for answering the main purpose of it, that of piercing armour. It was found, together with another dagger, in Barling's Eau, near Short Ferry, in 1788. 4. A sword in its scabbard, fig. 4. I could not by any force draw it out of the scabbard. On breaking the scabbard, I found the sword destroyed by rust; but the guard and hilt were still in a metallic state, and the pommel had been broken off. I have already described this instrument in the account of the brass arms. § 2. Chemical properties. — 1. The sword, fig. 8. (a) Being filed and polished, it was of the colour of steel. The blade was bent considerably before it was broken; and could not be broken without considerable force. Comparatively with soft steel, or malleable iron, it possessed little malleability. Under the hammer, file, and drill, it felt as hard as hardened steel. The snipt edges were hard, and strong enough to saw asunder the celts described in this paper. Its fractured surfaces showed a silvery kind of open grain, like steel which has been hardened by plunging it, when white hot, in cold water. The pommel and guard were much more mal- leable, and much less hard than the blade. (b) The blade, when red-hot, was malleable, but much less so than our common steel. On cooling gradually it became less hard than before; but it was not so soft as our common annealed, or distempered steel. By plunging the distempered piece of the blade, when white hot, in cold water, it was restored to its original hardness. By plunging the pommel and guard when white hot in cold water, they were ren- dered much harder; and by again igniting them, and letting them part with their fire gradually, they became as soft as they were originally, (c) The specific gra vity of the middle part of the blade, after filing off the coating, was 7.476. (d) The dissolution of 300 grs. of the blade in sulphuric acid and water, yielded nearly the same quantity of hydrogen gaz as an equal quantity of our steel affords. During the dissolution the mixture became black, and a black froth appeared on its surface ; and, after repose, there was a deposit of black matter. The solution, made boiling hot, was poured on a paper filter; and being filtrated, the filter was edulcorated, by repeatedly pouring on it pure water. The paper filter was stained black by the solution, and there was a small deposit of black matter in the apex of the cone of the filter. This black matter was carbon, in about the same proportion as our steel affords by the same treatment. The filtrated solution, on evaporation, was found to contain nothing but sulphate of iron. (e) A little nitric acid being dropped on the polished surface of the blade; and also on the pommel and guard; a black spot was produced on the parts wetted, (f) The tinned part of the pommel being just wetted with nitric acid, it became white. 2. The axe, fig. 9. (a) Being polished, it appeared of almost a silvery whiteness. — It was harder than malleable iron, but was not so hard as hard steel, for it was easily filed, and bored through with the drill. It was also cut through, and the cut surface was smooth and uniform, and close, as if made of the purest metal. It bent a little, notwithstanding its form and thickness; and required a very smart 1 2 60 PHILOSOPHICAL TRANSACTIONS. [ANNO 17 Q6. stroke with a heavy hammer to break it. The grain of the fractured part was like that of close-grained steel. — It was malleable both in its cold and ignited state. — It was almost as sonorous as bell- metal. (b) By quenching in cold water when ignited to whiteness, it became harder, more brittle, and open grained; but it could not be made so hard as the sword, fig. 8. By igniting the piece so hardened, and letting it part with its fire gradually, it was rendered much less hard than it was originally. The artist who assisted me in examining this tool, observed that it was only made of steel for about an inch from the edge; but that the rest was iron; for he conceived it to be impossible to be all steel, on account of the eye for the wooden shaft. However, on filing dif- ferent parts, and cutting the instrument, no seam could be discovered, where iron had been welded to steel; and every part appeared susceptible of induration and emollition, by the usual treatment of steel to produce these changes. (c) The specific gravity, before hammering, was 7.802, and after hammering the same piece, it was 7.S80. After ignition to whiteness and sudden quenching, the specific gravity was 7.384. — (d) 300 grs. of this metal dissolved in sulphuric acid and water, and afforded black matter and sulphate of iron ; with the same phe- nomena as the dissolution of the sword, fig. 8, afforded. The black matter was carbon, in apparently the same proportion as was obtained from the dissolution of the sword, fig. 8. — (e) Several parts of this axe being just wetted with nitric acid, they became black spots, as is the case on so applying this acid to steel. 3. The dagger, fig, 11. (a) Being polished, it had the appearance of steel. — It was not so hard as the sword, fig. 8 ; but it was so very strong and tough, that it was with difficulty broken, and could be bent very considerably. — Its fractured, or rather torn surface was open grained, and crystallized, — It was more malleable when cold, than hardened steel usually is. (b) In its ignited state it was very malleable. It was susceptible of induration and emollition, by the ordinary treatment to produce these changes in steel. — (c) The specific gravity of this dagger was 7.413. — (d) The dissolution in sulphuric acid and water afforded nothing but carbon and sulphate of iron, in about the same proportions as the dissolution of the sword, fig. 8. — (e) A black spot was produced by wetting this instrument with nitric acid. 4. The sword, fig. 4. (a) The hilt being polished, it appeared like steel. It was almost as hard as common hardened steel, and as malleable. — (b) The hilt was very malleable in its ignited state. It was hardened, but not considerably, by quenching in cold water when white hot. It was rendered softer, after being hard- ened, by ignition and gradually cooling. — (c) The specific gravity of the hilt was 7.647: and after ignition and quenching, it was 7 •427. — (d) The nitric acid pro- duced black spots when applied to the polished surfaces of this metal. — (e) The dis- solution in sulphuric acid and water afforded nothing but carbon and sulphate of iron. The carbon was in smaller quantity from this hilt, than from the sword, fig. 8, and not more than from common steel. ^ 3. Conclusions and remarks. — 1. It appears that all these instruments are of VOL. LXXXVI.] PHILOSOPHICAL TRANSACTIONS. 01 steel ; because they consist of carbon and iron ; because they are capable of indura- tion by plunging them when ignited in a cold medium; and they are softened by ignition and gradual cooling; they have the colour, texture, hardness, brittleness, malleability when ignited, and specific gravity of many sorts of steel. 2. The sword, fig. 8, appears to be the hardest; and the dagger, fig. 11, the softest steel of the above instruments. 3. These steel instruments appear to have been tempered, at least in the parts destined for cutting and piercing. 4. The axe, fig. Q, being all steel, affords a proof that the ancients were not ac- quainted with the art of manufacturing soft malleable iron: nor consequently of welding it with steel; and that the only state of iron which they used, and could manufacture, was steel. 5. Though it is most probable that these steel instruments were made of steel got directly from the ore, they show that the ancients could render such steel very malleable in its ignited state; and free from extraneous matters, and particularly from oxygen. 6. The different degrees of hardness and brittleness of these instruments may reasonably be imputed to the different proportions of carbon which they contain; and to the different degrees of cold applied in tempering them ; though the expe- riments were not made with such precision as to demonstrate the reality of these assigned causes. 7. It seems probable that the axe was tempered at a low temperature, and had been much hammered: hence its great specific gravity before hammering, and the little increase of its specific gravity by further hammering; and hence the great diminution of its specific gravity by quenching in its state of ignition to whiteness. 8. Iron and steel instruments are destroyed, commonly, by the oxygen of water, or oxygen of atmospherical air. The destruction of iron instruments is prevented by whatever prevents the union of the oxygen of these substances. On this prin- ciple the sword, fig. 8, was preserved by its varnish ; but the other tools must have owed their preservation to their having been accidentally coated with earthy matter; which perhaps contained principally clay. 9. The destruction of the iron sword by oxygen within the copper scabbard; and the preservation of the part of it not in contact with the copper, is a good ex- ample of the action of copper and water united in destroying iron, the copper remaining entire. This effect of copper on the iron bolts and nails, in copper-bot- tomed ships, is a loss of the greatest magnitude. Fig. 10, is another sword of the same kind as fig. 8, in Sir Jos. Banks's collection. XIX. On the Periodical Star a. Herculis ; ivith Remarks tending to establish the Rotatory Motion of the Stars on their Axes. To which is added a Second Cata- logue of the Comparative Brightness of the Stars. By Wm. Herschel, LL.D.} F. R. S. p. 452. In my first catalogue of the comparative brightness of the stars, I announced <» 02 PHILOSOPHICAL TRANSACTIONS. [ANNO 170(5. Herculis as a periodical star. The precision of the characters introduced in that catalogue is such, that the smallest alteration in the lustre of the stars may be dis- covered, by a proper attention to their expressions : the variation in the light of «. Herculis is however pretty considerable, and cannot easily be mistaken, when strictly compared to a proper standard. The star most conveniently situated for this purpose is x Ophiuchi ; and as I have had no reason, during the time of my obser- vations, to doubt the uniformity of its lustre, I have made use of it in the com- parisons; which seem to be sufficiently decisive, with regard to the periodical variations of the light of x Herculis. Other stars besides x Ophiuchi have also been consulted; but the unsteadiness of their light would draw me into difficulties, which at present it will be proper to avoid. The observations are found to contain at least 4 regular changes of the alternate increase and decay of the apparent lustre of our new periodical star, deduced from a comparison of its brightness with that of x Ophiuchi. In order, from the table of observations, to obtain the time of the period, if we first take all the successive observations from Sept. 16, till Nov. 28, they show very clearly that the star has completely gone through all its changes. For, ad- mitting a maximum of the light of a Herculis to have been Sept. 16, we find a minimum on Oct. 25 ; and a 2d maximum about Nov. 28. The period therefore is of somewhat more than 2 months duration. But as changeable stars are subject to temporary inequalities, which will render a determination of the length of a period, from a single series of changes, liable to considerable errors, we shall now take the assistance of the most distant observations. By an inspection of the table, we find again the first maximum to have been about Sept. 16, 1795; and the 4th the 14th of May, 1796. This being an interval of 241 days, in which 4 successive changes have been gone through, we obtain about 60^ days for the duration of the period. In confirmation of this computation, the table shows that our periodical star was very faint in August 1795; bright about the middle of Sep- tember; faint towards the end of October; bright the latter part of November; faint in December; bright in January, 1796; not observed in February; bright in March ; faint in April ; and lastly, bright again in May. This is just what should have happened according to the above determination, which, as we have seen, gives a period of 8 weeks, 4^ days. Greater accuracy can only be obtained by future observations. On the rotary motion of the stars on their axes. — The rotation of the fixed stars on their axes has been lately mentioned in a paper, where I could not have an opportunity to enter into the reasons why it ought to be admitted*. The rotatory motion of stars on their axes is a capital feature in their resemblance to the sun. It appears now, that we cannot refuse to admit such a motion, and that indeed it may be as evidently proved as the diurnal motion of the earth. Dark spots, or large portions of the surface, less luminous than the rest, turned alternately in certain directions, either towards or from us, will account for all the phenomena of • Phil. Trans, for the year 1795,—Orig. VOL. LXXXVI.] PHILOSOPHICAL TRANSACTIONS. ,fo periodical changes in the lustre of the stars, so satisfactorily, that we certainly need not look out for any other cause. Let us, however, take a review of any ob- jections that might be made. The periods in the change of the lustre of Algol, (3 Lyrae, S Cephei, and * An- tinoi, are short; being only 3, 5, 6, and 7 days respectively: those of o Ceti, the changeable star in Hydra, and that in the neck of the Swan are long, amounting to 331, 394, and 497 days. Will not a doubt arise whether the same cause can be admitted to explain indiscriminately phenomena that are so different in their duration? To this it may be answered, that the whole force of the objection is founded on our very limited acquaintance with the state of the heavens. Hitherto we have only had 7 stars whose periodical changes have been determined. No wonder then that proper connections between their different periods were wanting. But let us now place a Herculis among the list, which is not less than 60 days in performing one return of its changes. Here we find immediately, that the step from the rotation of « Herculis to that of 0 Ceti, is far less considerable than that from the period of Algol to the rotation of « Herculis; and thus a link in the chain is now supplied, which removes the objection that arose from the vacancy. There is however another instance of a slow rotatory motion ; and it is doubly instructive on this occasion. In a former paper it has been shown, that the 5th satellite of Saturn revolves on its axis in 79 days; this not only shows that very slow rotatory motions take place among the celestial bodies; but from the argu- ments that were brought to prove its rotation, which I believe no astronomer will oppose, we are led to apply the same reasoning to similar appearances among the fixed stars. A variation of light, owing to the alternate exposition of a more or less bright hemisphere of this periodical satellite, plainly indicates that the similar phenomenon of a changeable star, arises from the various lustre of the different parts of its surface, successively turned to us by its rotatory motion. The rota- tions of the sun and moon, and of several of the planets, become visible in a telescope by means of the spots on their surfaces; the remote situation and small- ness of the 5th satellite of Saturn leave us without this assistance; but what we can no longer perceive, with our best optical instruments, we now supply by rational arguments. The change in the light of the satellite proves the rotation; and the rotation once admitted, proves the existence of spots, or less luminous regions on its surface, which at setting off were only hypothetical. In the same manner a still more extended similarity between the sun and the stars offers itself, by the spots that now must also be admitted to take place on their surfaces, as well as on that of the sun. To return to the difficulty which has been started, it may be further urged, that there are some reasons to surmise that the 34 Cygni is a periodical star of 18 years return * ; and that other stars seem very slowly to diminish their lustre, and may probably recover it hereafter. In answer to this, I remark that it will not be neces- * Phil. Trans, for the year 1786, page 201.-— Orig. 64 PHILOSOPHICAL TRANSACTIONS. [anno 1796. sary to remove objections to the rotatory motion of the stars, inferred from their very slowly changeable lustre, till they come properly supported by well ascertained facts. Many causes in the physical construction of the stars may occasion an acci- dental and gradual increase or decay of brightness, not subject to any regularity in its duration. But when settled periods can be ascertained, though they should be of the most extended duration, it will not be difficult to find other causes to ex- plain them, without giving up the rotatory motion. When the biography of the stars, if I may be allowed the expression, is arrived to such perfection as to present us with a complete relation of all the incidents that have happened to the most eminent of them, we may then possibly not only be still more assured of their ro- tatory motion, but also perceive that they have other movements, such as nutations or changes in the inclination of their axes; which, added to bodies much flattened by quick rotatory motions, or surrounded by rings like Saturn, will easily account for many new phenomena that may then offer themselves to our extended views. After this follows the 2d catalogue of the comparative brightness of the stars; not necessary to be here re-printed. XX. Abstract of a Register of the Barometer, Thermometer, and Rain, at Lyndon, in Rutland, 1795. By Thos. Barker, Esq. p. 483. Barometer. Thermometer. Rain. In the House. Abroad. Lyndon. Highest. Lowest. Mean. Hig.lLow Mean Hig. Low Mean I Inches. Inches. Inches o o 0 0 O O Inch. Jan. Morn. Aftern. 29.95 28.63 29.54 35£ 36£ 25 25£ 80j 31 37 44 14 20 25 28| 1.640 Morn. 44 28 34j 47 18 31 Feb. Aftern. ' 28.49 13 45 29 35% 48 24£ 34£ 1-995 Morn. 45 33 40 47 20 36 Mar. Aftern. 29.82 28.15 30 47 35 4l£ 54 32 43 £ 2.101 Apr. Morn. Aftern. 29.71 28.80 31 50 54 41 411 45 47 h 51 62 36 41 42 k 51 1.574 May Morn. Aftern. 29.99 29. 18 69 64 67 42 46£ 52 55 59h 74 37 43 48£ 60J. 0.404 June Morn. Aftern. 2972 2903 42 621 67h 50 51 55j 57 60 77 43 51 52 6'4 2.799 July Morn. Aftern. 29-83 29.05 52 641 66 55 56 58 59 62\ 82 49 55 55 65h 1.683 Aug Morn. Aftern. 29.82 29.13 49 68 58£ 71 1 59h 62£ 6\\ 69\ 84 49 6o£ 58 71 1.3S0 Sept Morn. Aftern. 29.99 29.18 63 68 701 56 56 62 J 65 63 78h 43 55 54j 69 0.057 Oct. Morn. Aftern. 29.70 28.67 17 62£ 63£ 48 50 55 56 591 69 39 48 50 58 4.536 Nov Morn. ' Aftern. 30.13 28.53 37 51 52 36£ 37 44 45 48 53\ 24^ 32 38£ 1.850 Dec Morn. Aftern. 29.96 28.87 43 51 5\\ 41jJ 42 46 47 52 54 33 38 42£ 46£ 1.382 I leans. l 29.38 50 49 21.401 VOL. LXXXVI.] PHILOSOPHICAL TRANSACTIONS. (55 XXI. Observations on the Changes which Blood undergoes, when Extravasated into the Urinary Bladder, and retained for some Time in that Fiscus, mixed with the Urine. By Everard Home, Esq., F. R. S. p. 486. A gentleman, 71 years of age, in the spring 17Q5, found that in making water, the urine had the appearance of blood, and congealed into a solid mass as soon as received into the vessel. This complaint appeared to have arisen from the rupture of a vessel in one of the kidneys, for he had a pain in his loins, but none in the re- gion of the bladder. He seemed to void no water, for the whole quantity which was expelled at any one time, amounting to about 4 oz. formed itself into a coagu- lum ; next day he voided bloody water, which did not coagulate. This continued for 3 or 4 days, and then went entirely off. In the spring, 1796, he had a return of the same complaint. It came on in the evening of the 3d of April ; on the 4th it was very violent ; and in the afternoon there was a total suppression. A catheter was passed 6 or 7 times ; but the oval holes near the end of the instrument were always filled with coagulated blood, and no urine could be drawn off. On the 5 th, a larger catheter was passed, with small round holes, less likely to have the coagu- lum entangled in them, but no urine came away. In the evening it was introduced again, having its cavity completely lined with a flexible gum catheter, which was withdrawn as soon as the instrument was carried to the fundus of the bladder ; and in this way 4 oz. of a . bloody fluid were drawn off, which on exposure coagulated. On the morning of the 6th, a pint of bloody urine was drawn off; this operation was repeated 3 times in the 24 hours, and the same quantity was brought away each time. On the 7th, the urine drawn off was less tinged with blood; and when it was allowed to stand, the upper part became tolerably clear. There was little change in the circumstances for 6 days; but on the 13th the urine drawn off was of a darker red colour, and in smaller quantity. On the 16th, the colour was more of a light brown, and after standing some time, a whitish powder was deposited; the urine drawn off in the morning on getting up, was nearly of the natural appear- ance, but that brought away in the course of the day, had a deeper tinge, and more of the white sediment, which evidently passed off only with the last part of the urine. On the 19th, the urine was tolerably clear, and the white sediment more completely separated, and in greater quantity. In the course of the night, while laying in bed, the patient voided naturally in many different attempts, 4 oz. of water, but could not make any when up. The urine now continued clear from any tinge, but no more passed without the catheter being introduced, till the 28th, when he again made some water naturally, but could not completely empty the bladder; on the 2Qth, the quantity which required being drawn off was less; and by the 5th of May he made water as usual, at which time the sediment began to diminish, and gradually disappeared. From the symptoms which have been stated, it appears that part of the blood which passed into the bladder from the kidney had remained there, and formed a coagulum, which coagulum gave a bloody tinge to VOL. xviii. K 66 PHILOSOPHICAL TRANSACTIONS. [ANNO 17 Q6. the urine, and caused an inability to void it without assistance, till the coagulum was dissolved. With a view to ascertain how far this had been the case, and dis- cover what changes the blood undergoes when placed in such circumstances, I in- stituted the following experiments. They were performed by Mr. Charles Grover, a very ingenious surgeon, at present house surgeon in St. George's hospital. Exper. 1. 4 oz. of blood were drawn from the arm into a phial containing 4 oz. of fresh urine, and the phial was kept in the temperature of the human body; in 15 minutes the whole mixture formed a uniform firm coagulum, and appeared wholly composed of blood. This experiment was made to ascertain the probable time the blood would take to coagulate in the bladder. Exper. 2. 6oz. of blood were drawn from the arm into 6oz. of fresh urine; in 15 minutes the whole mass became one solid coagulum. In 7 hours, 6 drs. of clear fluid were separated from it; this was poured off, and the same quantity of fresh urine was added; after standing 9 hours it was poured off; some red globules were mixed with it, but sunk to the bottom undissolved. The coagulum had fresh urine added to it 3 times a day, the former urine being previously poured off, and allowed to stand some hours for examination. For the first 5 days the coagulum appeared to undergo little change, except becoming smaller in size, and the urine poured off from it was tolerably clear, but on standing deposited a dark cloudy se- diment. On the 6th day, the urine, when poured off from the coagulum, was of a dark red colour, and deposited a greater quantity of a dark coloured sediment, but on standing became tolerably clear. On the 9th day, the coagulum was re- duced to the size of the original quantity of blood drawn from the arm. On the 13th day, the size of the coagulum was a good deal reduced; the urine poured off from it was still more tinged with the red globules; but when allowed to stand, the upper part became clear, and free from the red tinge, and the sediment had the ap- pearance of a whitish powder. From this time the quantity of white sediment in- creased, and the size of the coagulum diminished. In its decrease from this period the loss was from its external surface, and nearly equally all round; what remained appearing like the nucleus of the original coagulum. On the 25th day, it was of the size of a large cherry, and on the 29th it entirely disappeared. Some red globules were very distinctly seen in the sediment along with the white powder. To see how far the changes the blood had undergone in this experiment depended on the peculiar properties of the urine, the following experiment was made, with blood and common water. Exper. 3. 6 oz. of blood were drawn from the arm into 6oz. of water. In a -j- of an hour, the whole became one solid coagulum. In 12 hours, 6 oz. of a clear water, of a bright red colour, were separated, nor did it on standing deposit any sediment. This coagulum had fresh water added to it twice a day, and what was poured off was allowed to stand for examination. The coagulum on the 2d day began to break; on the 5th had a putrid smell; and in 18 days was almost en- tirely dissolved. The water poured off was of a bright red colour from the be- VOL. LXXXVI.] PHILOSOPHICAL TRANSACTIONS. 67 ginning to the end of the experiment, in consequence of the red globules being dissolved; it had a very offensive smell, but never deposited any white sediment; the coagulating lymph dissolving from putrefaction. As it is evident, from the result of the last experiment, that the coagulum remaining so long undissolved in the 2d experiment depended on its being mixed with the urine, I was desirous of knowing whether it was the urine incorporated with the coagulum, .or that which sur- rounded it, which produced this effect. To determine this point I instituted the following experiment. Exper. 4. 4 oz. of blood were drawn from the arm into a cup, and allowed to coagulate ; 4 oz. more were drawn into a separate cup. From each of these equal portions of coagulum, at the end of 3 hours, 1 oz. of serum was separated, and poured off. To one of them fresh urine was added: to the other common water. The urine and water were changed night and morning. The water was tinged of a bright red colour throughout the whole experiment, and deposited no sediment. On the 8th day the coagulum was rather looser in its texture. On the 13th day it began to break, and by the 20th day it was nearly dissolved. The progress cor- responding with that of the coagulum in experiment 3. The urine the 2d day of the experiment was clear, but the bottom of the basin was covered with red glo- bules, undissolved. On the 5th day, the urine poured off was tinged of a bright red colour; similar to the water taken from the other coagulum; and after standing some hours a white sediment was deposited. On the 13th day it was looser in tex- ture, and more dissolved than the coagulum in the water. It continued to tinge the urine of a bright red colour, and what was poured off deposited a white sedi- ment in greater quantity. On the 18th, the coagulum was nearly dissolved; so that the coagulum immersed in the urine dissolved two days sooner than that in the water. From this experiment we find, that it was the urine incorporated with the coagulum in experiment 2, that prevented the red globules from dissolving, and preserved the coagulum for so long a time, since these effects were not produced by urine while simply surrounding the coagulum. If we compare experiment 2, with the result of the case, they agree so entirely, that it leaves no doubt of the process carried on in the bladder being similar to that which took place out of the body. The patient was unable to make water for 24 days, though the passages readily admitted, during the whole of that time, an uncommonly large instrument, which could not have been the case had there been any obstruction in them ; for 6 days more he voided it with difficulty, but afterwards made water very well. The coagulum out of the body was reduced in 25 days to the size of a cherry, and in 4 days more it was completely dissolved. The patient's urine became darker, from the red globules mixing with it in 9 days. In the experiment this took place in 5 days. The white sediment was first observed, in both instances, about the 12th day ; it continued to be deposited till the patient got well, and to the end of the experiment. k 2 68 PHILOSOPHICAL TRANSACTIONS. [ANNO 17 96. That the blood is capable of uniting with a quantity of urine equal to itself, so as to form a firm coagulum; that the red globules do not dissolve in a coagulum so formed; that an admixture of urine prevents the blood from becoming putrid; and that the coagulating lymph breaks down into parts almost resembling a soft powder, are facts which I believe to be new; — they may however have been before ascer- tained, though I have not been acquainted with them. They are certainly not generally known, and one object of the present paper is to communicate them to others. These facts, considered abstractedly, may not appear of much importance; but when compared with what takes place in the living body, and found to agree with the process the blood undergoes in the urinary bladder, they become of no small value, since they enable us to account for the symptoms that occur in that disease, and lead to the most simple and effectual mode of relieving them. XXII. On the Fructification of the Submersed Alg) + (a — m + pe) (b — n) — ah (1 + /a — pi) (1 + *)> which equals $ -f- fy, -f h — tyt + *fw ~ H*» + ab — lm _[_ Ipe — an + nm — nPe — a^ — •%• H" °bp£ — Qbv — abpv -J- abvpt = $ -f- jp -L. $v — $p£ — bm — bap + bpe + bapt — an — abv -f- nm — npe — abpv -|- abvpt -\- fy*v — Sttw. " To make use of this rule, it must be considered that the quantity Spy — $p& is so small that it may safely be disregarded; but nm — npe — abpv -f- abvpt, if the altitudes are not more than 5°, may amount to about 12/;, and therefore ought not to be neglected. The quantity e + at also differs very little from J, but is not quite equal to it. Let therefore a table be made under a double argument, namely, the altitudes of the moon and star, giving the value of ... . nm — n-ne — abpv + abvrrt + k*e -f- ba-Ki — bir, answering to different values of these altitudes, which call A. Let a 2d table be made under a double argument, namely, the altitude of the star and the apparent distance of the moon and star, giving the value of tr, which call d. Let a 3d table be made with the observed altitude for argument, giving the logarithm of am -\- a2/*; and let this quantity, answering to the moon's altitude, be palled m, and that answering to the star's altitude, n ; observing that the same table will do for the moon and star; but a 4th table should be made for the sun, so as to include its parallax; and, lastly, let a 5th table be made, with the moon's al- titude for argument, giving the logarithm of - = — , which call c. Then will cos. g = bo ^ J3 O CO • w bfl cu .— O^ 0 4J -W S.SP 0 cu on 5 '3 0 ■w . CO j_i 2} -a re bo is 0 •4J '*■"' co _C3 re bfl £> bfl si re bfl B'i ©•A Inc. co rt 2 bio Inc. a t* re -c 2 8 0 0 0 Inc. Jan. 56 36 47.3 55 38 47.5 62 51 57.2 30.32 29.00 29.72 Feb. *56 30 41.7 55.5 30.5 41.7 58.5 51 55.0 30.31 29-05 29.8 1 Mar. 60 26.5 41.0 5.9 27 41.4 60 47 54.0 30.44 29.50 30.03 April 70 36* 50.9 68.5 39 51.4 64.5 55 59.8 30.32 29-08 30.04 May 65 39 52.7 6*4 44 54.0 63 57 60.4 30.22j28.94 29.73 June 80 45 58.8 78 4.9 59.8 68.5 59 62.2 30.31 29.44 29.96 July 77.5 44.5 61.2 76.5 50 6*2.0 67 60 6*4.1 30. 18^29.37 29.79 Aug. 80 48.5 62.5 80 52 63.7 72 64, 67.2 30.41 29.71 30.06 Sept. 79-8 45 6'1.9 78 46* 61.4 72 6*1 66.1 30.28 29.46 29.96' Oct. 59 30 48.7 59 32 48.9 61 54.5 57.8 30.55 29.17 29.9 * Nov. 57 29 42.2 57 2.9 42.2 60 50 54.3 30.29 29. 18 29-83 Dec. 51.5 4 32.1 50.1 49 5 32.1 53 43 47.5 30.51 29.24 29.83 Whole ,.»r. 50.5 58.8 29.89 Hygrometer. Rain. 4-1 CO • D *2 U -*-" a ** m "5, re -a re -G S.5P >-c OJ cu bfl Ol + * 1' + *, 2l + * 3l+* 4' + * &c rately expressed by the equations J ; ' For, as the variable part z, of this exponent, may be taken of any dimensions, it may be so taken at each given term of the series, or for each particular value of x, that the equation x1 + ■ = y, may always correspond with the result of the experi- ments; and when this is done,* the value of z, and the law of its increase as x increases, will be known ; and this will show the relation of x to y, or of the elas- ticities of the generated fluid to their corresponding densities, in a clear and satis- factory manner. Without increasing the length of this paper still more, by giving an account in detail of all the various computations I made, in order, from the results of the experiments in the foregoing table, to ascertain the real value of z, and the rate at which it increases as x is increased, I shall content myself with merely giving the general results of these investigations, and referring for further information to the following table 2, where the agreement of the law founded on them, with the results of the foregoing experiments, may be seen. Having, from the results of the experiments in table 1, computed the different values of z, corresponding to all the different densities, or different charges of * True, when this is done for every term or value of x : but the law of progression will not be known farther than the terms which are actually compared. Y2 l64 PHILOSOPHICAL TRANSACTIONS. [ANNO 1797. powder, from 1 grain, or 3g thousandth parts, to 18 grains, or 702 thousandth parts of the capacity of the barrel, I found that while the density of the elastic fluid = x, expressed in thousandth parts, is increased from O to 1000, or till the powder com- pletely fills the space in which it is confined, the variable part z of the exponent of x} (l + z), is increased from 0 to XV- And though some of the experiments, and particularly those which were made with large charges of powder, seemed to indi- cate that while x is increased with an equable or uniform motion, z increases with a motion continually accelerated; yet, as the results of by far the greatest number of the other experiments showed the velocity of the increase of z to be equable, this circumstance, added to some other reasons drawn from the nature of the sub- ject, have induced me to assume the ratio of the increase of z to the increase of x as constant. But if, while x increases with an equable velocity from 0 to 1000, z is increased with an equable velocity from O to T\T then it is every where z to x as -^ to 1000; or 1000 z = tV?, and consequently z = j^^i and when x is = 1, it is z = 1 0*00 = 0.0004; and when x is greater or less than 1, it is z = 0.0004,r; and z being expunged, the general equation expressing the relation of x to y becomes xi + 0.0004* _. y.f and this is the equation which was used in computing the values of y, as expressed in the following table. In order that the elasticities might be ex- pressed in atmospheres, the values of y, as determined by this equation, were mul- tiplied by 1 .84 1 . If it be required to express the elasticity in pounds avoirdupois, then the value ofy, as determined by the foregoing equation, being multiplied by 27.615, will show how many pounds avoirdupois, pressing on a superficial inch will be equal to the pressure exerted by the elastic fluid in the case in question. Table II, General Results of the Experiments in Table I. on the Force of Fired Gunpowder. Computed elasticity of the gene- Actual elasticity, Difference of the The charge of Value of the rated fluid, or value of_y, ac- as shown bj computed and powder. exponent cording to the theorem the experi- the actual elas- 1+0.0004*. xi+o 0004* _ y- ments. ticities. In I n equal In In In In grains. parts. equal parts. Atmospheres. Atmospheres. Atmospheres. 1 39 1.0156 41.294 76.822 77.86 + 1.838 2 78 1.0312 89.357 164.506 182.30 + 17.794 3 117 1.0468 146.210 269.173 228.2 - 40.973 4 156 1.0624 213.784 393.577 382.4 - 11.177 5 195 1.0780 294.209 541.640 561.2 4- 19.560 6 234 1.0936 389-919 717.841 685.6 — 32.241 7 273 1.1092 503.723 927.353 811.7 - 115.653 8 312 1.1248 638.889 1176.19 1164.8 — 12.390 9 351 1.1404 799-223 1471.37 1551.3 + 79.930 10 390 1.1560 989.169 1821.06 1884.3 + 63.240 11 429 1.1716 1213.91 2234.81 2219. — 15.810 12 46'8 1.1872 1479-50 2723.77 2573.7 — 150.07 13 507 1.2028 1793. 3300.91 3283.3 — 17.61 14 546 1.2184 2162.69 3980.52 4008. + 27.48 15 585 1.2340 2598.18 4783.26 4722.5 - 60.76 16 624 1.2496 3110.73 5726.83 7090. + 1363.17 17 663 1.26'J2 3713.46 6836.46 18 702 1.2808 4421.69 8140.34 10977. 4- 2836.66 19 741 1.2964 5253.3 9671.33 20 780 1.3120 6229.14 11467.8 25.641 1000 1.4000 15848.9 29177.9 VOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. ] 65 The agreement of the elasticities, computed from the theorem x1 + o-°°°4* = y} with the actual elasticities as they were measured in the experiments, may be seen in the foregoing table; but this agreement may be seen in a much more striking manner by a bare inspection of the figure before-mentioned; for the line ad in this figure having been drawn from the computed elasticities, its general coincidence with the line ac of the experiments, shows how nearly the computed and the actual elasticities approach each other. And when the irregularities of the line ac, which must be attributed to the unavoidable errors of the experiments, are corrected, these 2 curves will be found to coincide with much precision throughout a considerable part of the range of the experiments; but towards the end of the set of experi- ments, when the charges of powder were considerably increased, the elasticities seem to have increased faster than, according to the assumed law, they ought to have done. From this circumstance, and from the immense force the charge must have exerted in the experiment, when the barrel was burst, I was led to suspect that the elastic force of the fluid generated in the combustion of gunpowder, when its density is great, is still much greater than these experiments seem to indicate; and a further investigation of the subject served to confirm me in this opinion. It has been shown that the force exerted by the charge in the experiment in which the barrel was burst could not have been less than the pressure of 54752 atmos- pheres; but the greatest force of the generated elastic fluid, when, the powder filling the space in which it is confined, its density is = 1000, on computing its elasticity by the theorem x1 +00004* = y3 turns out to be only equal to 29178 at- mospheres. In this computation the mean of the results of all the experiments in the foregoing set is taken as a standard to ascertain the value, expressed in atmos- pheres of y, and it is y X 1.841 = 29 178. But if, instead of taking the mean of the whole set of experiments as a standard, we select that experiment in which the force exerted by the powder appears to have been the greatest, yet in this case even the initial force of fired gunpowder, com- puted by the above rule, would be much too small. In the experiment N° 84, when the charge consisted of 18 grains of powder, and the density or value of x was 702, a weight equal to the pressure of 10977 atmospheres was raised. Here the value ofy (= xl + °-0004*) is found to be (70212808), = 4421.7; and to express this value of y in atmospheres, and at the same time to accommodate it to the actual result of the experiment, it must be multiplied by 2.4826; for it is 4421.7 (the value of y expressed in equal parts) to 10.977 (its value in atmospheres, as shown by the experiment), as 1 to 2.4826, and consequently 4421.7 X 2.4826= IO977. If now the value of y be computed on the same principles, when x is put = 1000, it will turn out to be y = l000I + o-4 = 15849; and this number expressed in atmospheres, by multiplying it by 2.4826, gives the value of y = 39346 atmos- pheres. This however falls still far short of 54752 atmospheres, the force the powder was actually found to exert when the charge filled the space in which it was confined. But in the 84th experiment, when 18 grains of powder were used, as 1(50 PHILOSOPHICAL TRANSACTIONS. [anno 1797. the weight (808 1 lbs. avoirdupois) was raised with a very loud report, it is more than probable that the force of the generated elastic fluid was in fact considerably greater than that at which it was estimated, namely, greater than the pressure of 10977 atmospheres. But, without wasting time in fruitless endeavours to reconcile anomalous experi- ments, which probably never can be made to agree, I shall hasten to give an ac- count of another set of experiments ; the results of which, it must be confessed, were still more various, extraordinary, and inexplicable. The machinery having been repaired and put in order, the experiments were recommenced in July, 1793, the weather at that time being very hot. The principal part of the apparatus, the barrel, had undergone a trifling alteration : on refitting and cleaning it, the dia- meter of its bore at the muzzle was found to be a little increased, so that a weight equal to 8081 lbs. avoirdupois, instead of being equal to IO977 atmospheres, as was the case in the former experiments, was now just equal to the pressure of 943 1 atmospheres. Though I was not at Munich when this last set of experiments was made, they however were undertaken at my request, and under my direction, and I have no reason to doubt of their having been executed with all possible care. They were all made by the same persons who were employed in making the first set; and as these experimenters may be supposed to have become expert in practice, and as they could not possibly have had any interest in deceiving me, I cannot suspect the accuracy of their reports. Table III. Experiments on the Force of \fired Gunpowder. m Weight employed to § State of the 1 The Charge of confine the elastic •c Time when the Expe- Atmosphere. Powder. Fluid. C S*o JJ Q riment was made, g ■I B §.s_§ General Remarks. £ 1703. 8 1 •S oSS In lbs. In <•* g E | 82* avoirdu- atmos- d o 1 n < e M Grs. 17 In ic ofth tyof pois. pheres. No. 86 h. m. 1st July 4 0 F. 88° Eng. In. 28.37 Parts. 663 lbs. 8081 9431 f The weight was raised with an \ astonishing loud report. 87 4 30 . . r In these three experiments the 88 4 45 . . , . 16 624 . . / weight was raised with a very 89 5 0 , . . . 15 585 . . I loud report. 90 5 30 , . . . 12 468 . . Weight not raised. 91 6 0 • • • • 13 507 .. 9431 € Weight but just raised, report \ very weak. 92 2d 9 0 71° 28.38 . . m m , . Raised, loud report. 93 9 30 . . . . 12 46*8 . . Raised, feeble report. 94 10 0 . . 9431 Raised, report very feeble. 95 10 30 80° .. Hi # _ . . Just moved, no report. 96" 3d 10 0 70° 28.55 12 468 9 # Not raised. 97 10 30 , , . # 13 507 . _ Not raised. 98 11 0 75° . . 14 546 # . 9431 Just raised, feeble report. 99 4th 9 0 70° 28.56 14 546 # # Not raised. 100 9 30 # . Not raised. 101 10 0 72° •• 15 585 •• r The weight was raised, the re- 1 port not very loud. VOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. m a i 1 Time when the Expe- riment was made, 1793. State of the Atmosphere. The Charge of Powder. Weight employed to confine the elastic Fluid. H w V V- O i o 1 9 S I pa e 4 o a. < a In 1000 parts of the capaci- ty of the bore. In lbs. avoirdu- pois. In atmos. pheres. General Remarks. No. 102 103 104 105 106 107 108 109 h. m. 4th July 10 30 8th 9 0 9 30 10 45 17th 9 0 9 45 10 30 11 0 F. 72° 74° 85° 75° Eng. In. 28.56 28.42 28.4 Grs. 15£ 13 12 11^ Parts. 585 507 468 lbs. 9431 Nearly as above. j" Raised, and with an uncom- l monly loud report. Raised, report very loud. f But just raised, the report very 1 feeble. Nearly as above. Not raised. Just moved, no report. The same as above. It appears from the foregoing table, that in the afternoon of the 1st of July, the weight (which was a heavy brass cannon, a 24 pounder, weighing 808 1 lbs. avoir- dupois), was not raised by 12 grs. of powder, but that 13 grs. raised it with an audible though weak, report. That the next morning, July 2d, at 10 o'clock, it was raised twice by charges of 12 grs. That in the morning of the 3d of July, it was not raised by 12 grs., nor by 13 grs. ; but that 14 grs. just raised it. That in the afternoon of the same day, 2 experiments were made with 14 grs. of powder, in neither of which the weight was raised ; but that in another experiment, in which 15 grs. of powder were used, it was raised with a moderate report. That in the morning of the 8th July, in 2 experiments, one with 15 grs., and the other with 13 grs. of powder, the weight was raised with a loud report; and in an experiment with 12 grs., it was raised with a feeble report. And lastly, that in 3 successive experiments, made in the morning of the 17th of July, the weight was raised by charges of 1 2 grs. Hence it appears, that under circumstances the most favourable to the developement of the force of gunpowder, a charge, = 12 grs., filling ^Vo of the cavity in which it is confined, on being fired, exerts a force against the sides of the containing vessel equal to the pressure of Q43 1 atmospheres ; which pressure amounts to 141465 lbs. avoirdupois on each superficial inch. Mr. Robins makes the initial, or greatest force of the fluid generated in the com- bustion of gunpowder, namely when the charge completely fills the space in which it is confined, to be only equal to the pressure of 1000 atmospheres.* It appears however, from the result of these experiments, that even admitting the elasticities * The fact however is, that the initial force is really various, gradually increasing as the charge of powder is increased, on account of the superior heat of the explosion. Mr. Robins's experiments were made with only small quantities of powder } and hence he obtained for his initial force the pressure of 1000 atmospheres 5 but by increasing the charges considerably, it is found that the said force is gradually increased to near 2000 atmospheres j as appears by Dr. Hutton's Course of Mathematics, vol. 2, p. 352, 353, the 5th edition, anno 1807. l68 PHILOSOPHICAL TRANSACTIONS. [ANNO 1797. to be as the densities, as Mr. Robins supposes them to be, the initial force of this generated elastic fluid must be at least 20 times greater than Mr. Robins deter- mined it ; for ,40608o ? tne density of the elastic fluid in the experiments in question, is to 1, its density when the powder quite fills the space in which it is confined, as Q43 1 atmospheres, the measure of its elastic force in the experiments in question, to 20108 atmospheres ; which, according to Mr. Robins's theory respecting the ratio of the elasticities to the densities, would be the measure of its initial force. But all my experiments tend uniformly to prove, that the elasticities increase faster than in the simple ratio of the corresponding densities ; consequently the initial force of the generated elastic fluid must necessarily be greater than the pressure of 201 OS atmospheres. In one of my experiments which I have often had occasion to mention, the force actually exerted by the fluid must have been at least equal to the pressure of 54752 atmospheres. The other experiments ought no doubt to show, at least, that it is possible that such an enormous force may have been exerted by the charge made use of; and this I think they actually indicate. In the first set of experiments, which were made when the weather was cold, though the results of them uniformly showed the force of the powder to be much less than it appeared to be in all the subsequent experiments, made with greater charges, and in warm weather, yet they all show that the ratio of the elasticity of the generated fluid to its density is very different from that which Mr. Robins's theory supposes }* and that this ratio increases as the density of the fluid is in- creased. Supposing, what on many accounts appears to be extremely probable, that this ratio increases uniformly, or with an equable celerity, while the density is uniformly augmented ; and supposing further, that the velocity and limit of its in- crease have been rightly determined from the result of the set of experiments, table 1 , which were made with that view ; then, from the result of the experiments of which we have just been giving an account, in which 12 grs. of powder exerted a force equal to 9431 atmospheres, taking these experiments as a standard, we can, with the help of the theorem a»i +0.0004* = y, deduced from the former set of ex- periments, compute the initial force of fired gunpowder, thus : The density of the elastic fluid, when 12 grs. of powder are used for the charge, being = 468, it is 468Il872= y = 1479.5 ; and in order that this value of y may correspond with the result of the experiment, and be expressed in atmospheres, it must be multiplied by a certain co-efficient, which will be found by dividing the value of y expressed in atmospheres, as shown by the experiment, by the number * Though this circumstance, of the ratio of the elasticity to the density of the fluid, be here mentioned as if it related to the same thing in the 2 cases, they are yet however quite different : in these experi- ments it means the ratio of the charge of powder, or quantity of generated fluid in the same space, to its strength or elasticity ; but in Mr. Robins it means also that the elasticity of the same quantity of fluid, when it occupies different spaces, as when following and impelling a ball along the barrel of a gun, is in the ratio of the decreasing densities, or inversely as those spaces. Besides, this property, in both these respects, is not merely a matter of supposition in Mr. Robins's theory, but the consequence of experi- mental proof, both by himself and other eminent members of the a. s. VOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. \Qq here found indicating its value, as determined by computation-. It is therefore tHt.t = 6.3744 for the value of this co-efficient, and this multiplied into the number 147Q.5, gives 9431 for the value of y in atmospheres. Again, the density being supposed = 1000 (or, that the charge of powder com- pletely fills the cavity in which it is confined), in that case it will be 1000'+°-4 = y = 1584g, and this number being turned into atmospheres by being multiplied by the co-efficient above found (= 6.3744), gives 101021 atmospheres for the mea- sure of the initial force of the elastic fluid generated in the combustion of gun- powder. Enormous as this force appears, I do not think it over-rated ; for nothing much short of such an inconceivable force can, in my opinion, ever explain in a satisfactory manner the bursting of the barrel so often mentioned ; and to this we may add, that, as in 7 different experiments, all made with charges of 1 2 grs. of powder, there were no less than 5 in which the weight was raised with a report, and as the same weight was moved in 3 different experiments in which the charge con- sisted of less than 12 grs., there does not appear to be any reason whatever for doubt with regard to the principal fact on which the above computation is founded.* There is an objection however, that may be made to these decisions respecting the force of gunpowder, which, on the first view, appears of considerable import- ance ; but on a more careful examination it will be found to have no weight. If the force of fired gunpowder is so very great, how does it happen that fire-arms and artillery of all kinds, which certainly are not calculated to withstand so enormous a force, are not always burst when they are used ? I might answer this question by another, by asking how it happened that the barrel used in my experiments, and which was more than 10 times stronger in proportion to the size of its bore than ever a piece of ordnance was formed, could be burst by the force of gunpowder, if its force is not in fact much greater than it has ever been supposed to be ? But it is not necessary to have recourse to such a shift to get out of this difficulty : there is nothing more to do than to show, which may easily be done, that the combustion of gunpowder is less rapid than it has hitherto been supposed to be, and the objec- tion in question falls to the ground. Mr. Robins's theory supposes that all the powder of which a charge consists is not only set on fire, but that it is actually con- sumed and " converted into an elastic fluid before the bullet is sensibly moved from its place." I have already, in the former part of this paper, offered several reasons which appeared to me to prove that, though the inflammation of gunpowder is very rapid, yet the progress of the combustion is by no means so instantaneous as has been imagined. I shall now give an account of some experiments which put that matter out of all doubt. * Reasons, however, have been given in the foregoing notes, not only for doubt of such computations, but for proof of the fallacy of the principles on which they are made. One might have expected that th« enormous number of 1 00,000 atmospheres might have staggered any philosopher ! VOL. XVIII. Z 170 PHILOSOPHICAL TRANSACTIONS. [ANNO 1/97. It is a fact well known, that on the discharge of fire-arms of all kinds, cannon and mortars as well as muskets, there is always a considerable quantity of uncon- sumed grains of gunpowder blown out of them; and, what is yery remarkable, and, as it leads directly to a discovery of the cause of this effect, is highly de- serving of consideration, these unconsumed grains are not merely blown out of the muzzles of fire-arms; they come out also by their vents or touch-holes, where the fire enters to inflame the charge; as many persons who have had the misfortune to stand with their faces near the touch-hole of a musket, when it has been discharged, have found to their cost. Now it appears to me to be extremely improbable, if not absolutely impossible, that a grain of gunpowder actually in the chamber of the piece, and completely surrounded by flame, should, by the action of that very flame, be blown out of it, without being at the same time set on fire. But if these grains of powder are actually on fire when they come out of the piece, and are af- terwards found at a distance from it unconsumed, this is, in my opinion, a most decisive proof, not only that the combustion of gunpowder is by no means so rapid as has generally been thought to be, but also, what will doubtless appear quite in- credible, that if a grain of gunpowder, actually on fire, and burning with the utmost violence over the whole extent of its surface, be projected with a very great velocity into a cold atmosphere, the fire will be extinguished, and the remains of the grain will fall to the ground unchanged, and as inflammable as before. This extraordinary fact was ascertained beyond all possibility of doubt by the fol- lowing experiments. Having procured from a powder-mill in the neighbourhood of the city of Munich a quantity of gunpowder, all of the same mass, but formed into grains of very different sizes, some as small as the grains of the finest Battel powder, and the largest of them nearly the size of large pease, I placed a number of vertical screens of very thin paper, one behind another, at the distance of 12 inches from each other; and loading a common musket repeatedly with this powder, sometimes without, and sometimes with a wad, I fired it against the fore- most screen, and observed the quantity and effects of the unconsumed grains of powder which impinged against it. The screens were so contrived, by means of double frames united by hinges, that the paper could be changed with very little trouble, and it was actually changed after every experiment. The distance from the muzzle of the gun to the first screen was not always the same; in some of the experiments it was only 8 feet, in others it was 10, and in some 12 feet. The charge of powder was varied in a great number of different ways, but the most in- teresting experiments were made with one single large grain of powder, propelled by smaller and larger charges of very fine-grained powder. These large grains never failed to reach the screen ; and though they sometimes appeared to have been broken into several pieces, by the force of the explosion, yet they frequently reached the first screen entire; and sometimes passed through all the screens, 5 in number, without being broken. When they were propelled by large charges, and consequently with great velocity, they were seldom on fire when VOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. \J \ they arrived at the first screen, which was evident not only from their not setting fire to the paper, which they sometimes did, but also from their being found stick- ing in a soft board, against which they struck, after having passed through all the 5 screens; or leaving visible marks of their having impinged against it, and being broken to pieces and dispersed by the blow. These pieces were often found lying on the ground ; and from their forms and dimensions, as well as from other ap- pearances, it was often quite evident that the little globe of powder had been on fire, and that its diameter had been diminished by the combustion, before the fire was put out on the globe being projected into the cold atmosphere. The holes made in the screen by the little globe in its passage through them, seemed also to indicate that its diameter had been diminished. That these globes or large grains of powder were always set on fire by the com- bustion of the charge can hardly be doubted. This certainly happened in many of the experiments, for they arrived at the screens on fire, and set fire to the paper ; and in the experiments in which they were projected with small velocities, they were often seen to pass through the air on fire ; and when this was the case no vestige was to be found. They sometimes passed, on fire, through several of the foremost screens without setting them on fire, and set fire to one or more of the hindmost, and then went on and impinged against the board, which was placed at the distance of 12 inches behind the last screen. It is hardly necessary for me to observe, that all these experiments prove that the combustion of gunpowder is very far from being so instantaneous as has generally been imagined *. I will just mention one experiment more, in which this was shown in a manner still more striking, and not less conclusive. A small piece of red-hot iron being dropped down into the chamber of a common horse pistol, and the pistol being elevated to an angle of about 45 degrees, on dropping down into its barrel one of the small globes of powder, of the size of a pea, it took fire, and was projected into the atmosphere by the elastic fluid generated in its own combustion, leaving a very beautiful train of light behind it, and disappearing all at once, like a falling star. This amusing experiment was repeated very often, and with globes of different sizes. When very small ones were used singly, they were commonly consumed entirely before they came out of the barrel of the pistol ; but when several of them were used to- gether, some, if not all of them were commonly projected into the atmosphere on fire. I shall conclude this paper by some observations on the practical uses and improve- ments that may probably be derived from these discoveries, respecting the great expansive force of the fluid generated in the combustion of gunpowder. As the slowness of the combustion of gunpowder is undoubtedly the cause which has pre- * It- is not surprizing that the burning of these solid globes or lumps of gunpowder should be different from the same substance in the state of powder or small grains, its proper and useful state, in which the fire can pass freely between the grains. The common case, of comparatively slow burning, in a sky- rocket, when the powder is hard beaten together, nearly like the solid mass, is well known. z a 172 PHILOSOPHICAL TRANSACTIONS. [ANNO 1797. vented its enormous and almost incredible force from being discovered so it is evident, that the readiest way to increase its effects is to contrive matters so as to accelerate its inflammation and combustion. This may be done in various ways, but the most simple and most effectual manner of doing it would, in my opinion be to set fire to the charge of powder by shooting, through a small opening, the flame of a smaller charge into the midst of it. I contrived an instrument on this principle for firing cannon 3 or 4 years ago, and it was found on repeated trials to be useful, convenient in practice, and not liable to accidents. It also supersedes the necessity of using priming, of vent tubes, port-fires, and matches; and on that account I imagined it might be of use in the British navy. Whether it has been found to be so or not I have not yet heard*. Another infallible method of increasing very considerably the effect of gunpowder in fire-arms of all sorts and dimensions, would be to cause the bullet to fit the bore exactly, or without windage, in that part of the bore at least where the bullet rests on the charge-j"". for when the bullet does not completely close the opening of the chamber, not only much of the elastic fluid generated in the first moment of the combustion of the charge escapes by the sides of the bullet, but, what is of still greater importance, a considerable part of the unconsumed powder is blown out of the chamber along with it, in a state of actual combustion, and getting before the bullet continues to burn on as it passes through the whole length of the bore, by which the motion of the bullet is much- impeded. The loss of force arising from this cause is, in some cases almost incredible; and it is by no means difficult to contrive matters so as to render it very apparent, and also to prevent it. If a common horse pistol be fired with a loose ball, and so small a charge of powder that the ball shall not be able to penetrate a deal board so deep as to stick in it when fired against it from the distance of 6 feet; the same ball, discharged from the same pistol, with the same charge of powder, may be made to pass quite through one deal board, and bury itsejf in a 2d placed behind it, merely by pre- venting the loss of force which arises from what is called windage; as I have found more than once by actual experiment. I have in my possession a musket, from which, with a common musket charge of powder, I fire 1 bullets at once with the same velocity that a single bullet is discharged from a musket on the common construction, with the same quantity of powder. And, what renders the experiment still more striking, the diameter of the bore of my musket is exactly the same as that of a common musket, except only in that part of it where it joins the chamber, in which part it is just so much * By many accurate experiments made by the Artillery at Woolwich, it has been found that firing the charge of powder in different parts of it, makes no sort of difference in the effects, whether it is fired in the middle, or at either end, or at the upper side or under side, &c. + This is no new discovery or observation. It was particularly insisted on in the paper on the Force of Fired Gunpowder, in the Philos. Trans, anno 1778, p. 50, &c. And indeed, it is by taking advan- tage of this circumstance solely, that the ordnance called carronades have acquired such boasted effects.. VOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. ,173 contracted that the bullet which is next to the powder may stick fast in it. I ought to add, that though the bullets are of the common size, and are always consider- ably less in diameter than the bore, means are used which effectually prevent the loss of force by windage ; and to this last circumstance it is doubtless owing, in a great measure, that the charge appears to exert so great a force in propelling the bullets. That the conical form of the lower part of the bore, where it unites with the chamber, has a considerable share in producing this extraordinary effect, is however very certain, as I have found by experiments made with a view merely to ascertain that fact. I finish this paper by a computation, showing that the force of the elastic fluid generated in the combustion of gunpowder, enormous as it is, may be satisfactorily accounted for on the supposition that its force depends solely on the elasticity of watery vapour, or steam*. It has been shown by a variety of experiments made in England and in other countries, and lately by a well-conducted set of experiments made in France by M. de Betancour, and published in Paris under the auspices of the Royal Academy of Sciences, in the year 179O, that the elasticity of steam is doubled by every addition of temperature equal to 30 degrees of Fahrenheit's ther- mometer. Supposing now a cavity of any dimensions, equal in capacity to 1 cubic inch, for instance, to be filled with gunpowder, and that on the combustion of the powder, and in consequence of it, this space is filled with steam (and I shall pre- sently show that the water, existing in the powder as water, is abundantly suffi- cient for generating this steam) ; if we know the heat communicated to this steam in the combustion of powder, we can compute the elasticity it acquires by being so heated. Now it is certain that the heat generated in the combustion of gunpowder cannot possibly be less than that of red-hot iron. It is probably much greater, but we will suppose it to be only equal to 1000 degrees of Fahrenheit's scale, or some- thing less than iron visibly red-hot in day-light. This is about as much hotter than boiling linseed oil, as boiling linseed oil is hotter than boiling water. As the elastic force of steam is just equal to the mean pressure of the atmosphere when its tem- perature is equal to that of boiling water, or to 212° of Fahrenheit's thermometer, and as its elasticity is doubled by every addition of temperature equal to 30 degrees of the same scale,-}- with the heat of 212° + 30° = 242° its elasticity will be equal * Having, by a fallacious mode of comparison applied to his experiments, raised the force of fired gunpowder to a monstrous degree, the author now has recourse to a most preposterous invention to account for it, viz. moisture in the powder! whicl^has always heretofore been found greatly to injure and depress the strength of that substance. f We have not been able to discover that this rate of increase, in the strength of the steam, is ac- cording to the scale in Betancour's experiments. An account of these experiments, with the table of corresponding temperature and strength of the steam, may be seen at the end of Dr. Hutton's Philos, Dictionary, and may doubtless be found in other places in this country. Now in this table it does not appear that the law of the increase of strength is at all conformable to the law above-mentioned, or that the strength is doubled by the addition of any constant number of degrees of heat whatever. These 174 PHILOSOPHICAL TRANSACTIONS. [ANNO 1797. to the pressure of 2 atmospheres; at the temperature of 242° -f 30° = 272° it will equal 4 atmospheres; at 272 at 302 at 332 at 362 at 392 at 422 at 452 at 482 at 512 at 542 + 30° = 302° + 30 = 332 + 30 = 362 -j- 30 = 392 -f 30 = 422 + 30 =. 452 -f 30 + 30 + 30 + 30 it will equal 8 atmospheres; 16 32 64 128 256 = 482 512 = 512 1024 = 542 2048 = 572 4096 at 572 -|- 30 = 602, (or 2 degrees above the heat of boiling lin- seed oil), its elasticity will be equal to the pressure of 8 1 92 atmospheres, or above 8 times greater than the utmost force of the fluid generated in the combustion of gunpowder, according to Mr. Robins's computation. But the heat generated in the combustion of gunpowder is much greater than that of 602° of Fahrenheit's thermometer, consequently the elasticity of the steam generated from the water contained in the powder must of necessity be much greater than the pressure of 8 192 atmospheres. Following up our computations on the principles assumed, (and they are founded on the most incontrovertible experiments) we shall find that, at the temperature the elasticity will be equal to the pressure of of 602° + 30° = 632° 1 6384 atmospheres; at 632 + 30 = 662 32768 at 662 + 30 = 692 65536 and at 692 -f- 30 = 722, the elasticity will be equal to the pressure of 131072 atmospheres, which is 130 times greater than the elastic force assigned by Mr. Robins to the fluid generated in the combustion of gunpowder; and about » part greater than my experiments indicated it to be. degrees of heat, in this table, are according to Reaumur's thermometer, is contained in the annexed tablet j where the 1st column shows several degrees of strength of the steam, being in fact the number of French inches of the mercurial barometer that are balanced or sustained by the steam ; in the 2d column are the corresponding degrees of heat of the steam, expressed by the degrees of Reaumur's thermometer j and in the 3d column are the differences of these degrees, which are not the same number or difference, but always increasing. Hence it appears, that while the numbers in the 1st column, denoting the strength of the steam, are always doubled, or nearly so, those in the 2d column, denoting the corresponding heat, are always increased by differences that are unequal. Were the calculation carried on, always doubling the elasticity for the constant addition of 30° of Fahrenheit's thermometer, till arriving at 1000° of heat, we should obtain the monstrous quantity of about 100 millions of atmospheres for the pressure of the elastic fluid ! A specimen of those numbers Dif. 2 3 5 7 8 10 11 12 13 14 15 Strength. Heat. 0.0346 2° 0.0747 4 0.1508 7 0.3039 12 0.6283 19 1.2127 27 2.4401 37 4.8386 48 9-6280 60 19.433 73 39.697 87 77.359 102 VOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. 175 But even here the heat is still much below that which is most undoubtedly gene- rated in the combustion of gunpowder. The temperature which is indicated by 722° of Fahrenheit's scale, (which is only 122 degrees higher than that of boiling quicksilver, or boiling linseed oil), falls short of the heat of iron which is visibly red-hot in day-light by 355 degrees: but the flame of gunpowder has been found to melt brass, when this metal, in very small particles, has been mixed with the powder; and it is well known that to melt brass a heat is required equal to that of 3807 degrees of Fahrenheit's scale; 2730 degrees above the heat of red-hot iron or 3085 degrees higher than the temperature which gives to steam an elasticity equal to the pressure of 131072 atmospheres. That the elasticity of steam would actually be increased by heat in the ratio here assumed, can hardly be doubted. It has absolutely been found to increase in this ratio in all the changes of temperature between the point of boiling water, I may even say of freezing water, and that of 280° of Fahrenheit's scale; and there does not appear to be any reason why the same law should not hold in higher temperatures. A doubt might possibly arise with respect to the existence of a sufficient quantity of water in gunpowder, to fill the space in which the powder is fired, with steam, at the moment of the explosion; but this doubt may easily be removed. The best gunpowder, such as was used in my experiments, is composed of 70 parts in weight of nitre, 18 parts of sulphur, and ]6 parts of charcoal; hence 100 parts of this powder contain 67 -ro Parts °f nitre, 17-jV parts of sulphur, and of charcoal 15-^ parts. Mr. Kirwan has shown that in 100 parts of nitre there are 7 parts of water of crystallization; consequently, in 100 parts of gunpowder, as it contains 67-jV parts of nitre, there must be 4 i0'0\ parts of water. Now as 1 cubic inch of gunpowder, when the powder is well shaken together, weighs exactly as much as 1 cubic inch of water at the temperature of 55° p. namely 253.175 grs. Troy, a cubic inch of gunpowder in its driest state must con- tain at least lO-^Vograins of water; for it is 100 to 4.711, as 253.175 to IO.927. But besides the water of crystallization which exists in the nitre, there is always a considerable quantity of water in gunpowder, in that state in which it makes bodies damp or moist. Charcoal exposed to the air has been found to absorb nearly -f of its weight of water; and by experiments I have made on gunpowder, by ascertain- ing its loss of weight on being much dried, and its acquiring this lost weight again on being exposed to the air, I have reason to think that the power of the charcoal, which enters into the composition of gunpowder, to absorb water remains unim- paired, and that it actually retains as much water in that state, as it would retain were it not mixed with the nitre and the sulphur. As there are 15vV parts of charcoal in 100 parts of gunpowder, in 1 cubic inch of gunpowder = 253.175 grains Troy, there must be 38.989 grains of charcoal; and if we suppose -f of the apparent weight of this charcoal to be water, this will give 4.873 grains in weight for the water which exists in the form of moisture in 1 cubic inch of gunpowder. That this estimation is not too high, is evident from the 170* PHILOSOPHICAL TRANSACTIONS. [ANNO 1797. following experiment. 1 160 grains Troy of apparently dry gunpowder, taken from the middle of a cask, on being exposed 15 minutes in dry air, heated to the tem- perature of about 200°, was found to have lost 1 1 grains of its weight. This shows that each cubic inch of this gunpowder actually gave out 2^ grains of water on being exposed to this heat; and there is no doubt but that at the end of the experiment it still retained much more water than it had parted with. If now we compute the quantity of water which would be sufficient, when re- duced to steam under the mean pressure of the atmosphere, to fill a space equal in capacity to 1 cubic inch, we shall find that either that contained in the nitre which enters into the composition of 1 cubic inch of gunpowder as water of crystalliza- tion, or even that small quantity which exists in the powder in the state of mois- ture, will be much more than sufficient for that purpose. Though the density of steam has not been determined with that degree of pre- cision that could be wished, yet it is quite certain that it cannot be less than 2000 times rarer than water, when both are at the temperature of 212°. Some have supposed it to be more than 10,000 times rarer than water, and experiments have been made which seem to render this opinion not improbable; but we will take its density at the highest possible estimation, and suppose it to be only 2000 times rarer than water. As 1 cubic inch of water weighs 253.175 grains, the water contained in 1 cubic inch of steam at the temperature of 212° will be 4 0'00 part of 253.175 grains, or 0.1 2659 of a grain. But we have seen that 1 cubic in,ch of gunpowder contains 10. 927 grains of water of crystallization, and 4.873 grains in a state of moisture. Consequently the quantity of water of crystallization in gun- powder is 86 times greater, and the quantity which exists in it in a state of mois- ture is 38 times greater, than that which would be required to form a quantity of steam sufficient to fill completely the space occupied by the powder. Hence we may venture to conclude, that the quantity of water actually existing in gunpowder, is much more than sufficient to generate all the steam that would be necessary to account for the force displayed in the combustion of gunpowder, supposing that force to depend solely on the action of steam, even though no water should be generated in the combustion of the gunpowder. It is even very probable that there is more of it than is wanted, and that the force of gunpowder would be still greater, could the quantity of water it contains be diminished. From this computation it v*ould appear, that the difficulty is not to account for the force actually exerted by fired gunpowder, but to explain the reason why it does not exert a much greater force. But I shall leave these investigations to those who have more leisure than I now have to prosecute them.* * We have bestowed more than ordinary remarks on this paper, as the experiments are exceedingly curious, the observations ingenious, and the subject of great importance. The author has greatly merited the praise of the philosophical world for his ingenuity and uncommon exertions, and the mi- nuteness with which he has related all the circumstances. But as we have often heard it remarked that Count R. did not always understand his own experiments, particularly in the case of the present paper \ VOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. J 77 XIII. A Third Catalogue of the Comparative Brightness of the Stars; with an Introductory Account of an Index to Mr. Flamsteed's Observations of the Fixed Stars contained in the id Volume of the Historia Ccelestis. To which are added, several Useful Results derived from that Index. By Win. Herschel, LL. D., F. R. S. p. 293. In my earliest reviews of the heavens, I was much surprized to find many of the stars of the British catalogue missing. Taking it for granted that this cata- logue was faultless, I supposed them to be lost. The deviation of many stars from the magnitude assigned to them in that catalogue, for the same reason, I con- sidered as changes in the lustre of the stars. Soon after however I perceived that these conclusions had been premature, and wished it were possible to find some method that might serve to direct us from the stars in the British catalogue, to the original observations which have served as a foundation to it. The labour and time required for making a proper index withheld me continually from undertaking the construction of it: but when I began to put the method of comparative bright- ness in practice, with a view to form a generated catalogue, I found the indispen- sible necessity of having this index recur so forcibly, that I recommended it to my sister to undertake the arduous task. At my request, and according to a plan which I laid down, she began the work about 20 months ago, and has lately finished it. The index has been made in the following manner. Every observation on the fixed stars contained in the 2d volume of the Historia Ccelestis was examined first, by casting up again all the numbers of the screws, in order to detect any error that might have been committed in reading off the zenith-distance by diagonal lines. The result of the computation being then corrected by the quantity given at the head of the column, and, refraction being allowed for, was next compared with the column of the correct zenith-distance as a check. Every star was now computed by a known preceding or following star; and its place according to the result of the computation laid down in the Atlas Ccelestis, by means of proportional compasses. This was necessary, in order to ascertain the observed star: for the observations contain but little information on the subject; most of the small stars being without names, letters, or descriptions. The many errors in the names of the constellations affixed to the stars, and in the letters by which they are denoted, also demanded a more scrupulous attention; so that only their relative situation* examined by calculation, could ascertain what the stars really were which had been observed. Every observed star being now ascertained, its number in the British catalogue was added in the margin at the end of the line of the observation ; and a book with and as we could not always agree in his deductions from them, especially in the most important particu- lars ; we have found it our duty to the public to show, by our observations, our conviction that he has completely failed in the most important circumstances of the inquiry. VOL. XVIII. A A 178 PHILOSOPHICAL TRANSACTIONS. [ANNO 1797. all the constellations and number of the stars of the same catalogue, with large blank spaces to each of them, being provided, an entry of the page where Flam- steed's observation is to be found, was made in its proper place. If the star observed was not in the British catalogue, it was marked as such in the margin of the ob- servations; and being provided with another book of constellations and numbers, it was entered into the blank space belonging to some known preceding or following star, by which its place had been settled. The Greek and English letters used by Flamsteed, whether they were such as had been introduced before, or which he thought it expedient to add to them at the time of observation, were also entered in their proper places; and to complete the whole, the magnitude affixed to the stars was also joined to the entry made in the blank spaces of the index. I have been so far particular in giving the method by which the index has been constructed, that it may appear what confidence ought to be given to the conclu- sions which will be drawn from its report. About 3 or 4 examples of its use, will completely show how the results, which will be mentioned, have been obtained. Suppose I wish to be informed of the particulars relating to the 13th Arietis. By the index I am referred, in the column allotted for that star, to 77 observations; and find that Flamsteed used the letter a 72 times, and that in 2 places he calls it a star of the 2d magnitude; the rest of the observations being without any estima- mation of its brightness. If it be required to know Flamsteed's observations on the 34th Tauri, which star is supposed to have been the Georgian planet, mistaken by Flamsteed for a small fixed star*; we find in our index, that on page 86, De- cember 13, 1690, a star of the 6th magnitude was observed, which answers to the place of the 34th Tauri in the British catalogue; and that no other observation of the same star occurs in the 2d volume. In my catalogue of comparative bright- ness, the 34th Tauri is set down among the lost stars, it being no longer to be seen in the place where it was observed by Flamsteed. ; If in my review of the heavens I cannot find 38 Leonis, and examine this index, I am at once informed that Flamsteed never observed such a star; and that of con- sequence it has been inserted in the British catalogue by some mistake or other. In many cases, these mistakes may be easily traced, as has been shown with regard to this star in my 2d catalogue of comparative brightness. See the note to 38 Leonis. When we wish to examine 90 Ceti in the heavens, and cannot find it, we are in- formed by our index, that 90 Ceti is the same star with J Eridani; and that con- sequently we are not to look out for 2 different stars. We may now proceed to give some general results that are to be obtained from an inspection of our index. They are as follow. 11 1 stars inserted in the British catalogue have never been observed by Flamsteed. This will explain why so many stars in the heavens seem to have been lost. There are 39 stars in the same cata- logue that want considerable corrections in right-ascension or polar-distance. In many it amounts to several degrees. 54 stars more, besides the 39 that are taken * See Astronomishes Jahr-Buch for 1789, page 202. — Orig. VOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. IJQ from the erroneous stars in the catalogue, want corrections in the Atlas Coelestis ; several of them also of many degrees. 42 stars are set down, which must be re- duced to 21; each going by 2 names in different constellations. 371 stars, com- pletely observed both in right-ascension and zenith-distance, have been totally over- looked. 35 more, which have 1 of the 2, either right-ascension or polar-distance doubtful, have been omitted. 86 with only the polar-distance, and 13 with only the right-ascension, have also been unnoticed. About 50 more that are pointed out by pretty clear descriptions, are also neglected : so that on the whole between 5 and 6 hundred stars observed by Flamsteed, have been overlooked when the British catalogue was framed. These additional stars will make a considerable catalogue, which is already drawn up and nearly finished by Miss Herschel, who is in hopes that it may prove a valuable acquisition to astronomers. Neither the index to Flamsteed's observations, nor the catalogue of omitted stars, were finished when my former 2 catalogues of comparative brightness were given; I shall therefore now select a few notes to be added to those which are at the end of these catalogues. They will contain such additional light as I have been enabled to gather from this newly acquired assist- ance. Additional Notes to the Stars in the First Catalogue of the comparative Brightness of the Stars. Aquarius. — 25 Is the same star with 6 Pegasi. There are but 2 observations of it. The first is on page 57; Flamsteed calls it "in constellatione Pegasi sub capite." The 2d, on page 71, is described " in constellatione Aquarii trianguli in capite praecedens et borealis." Here we see that the double insertion in the cata- logue is owing to the star's having been called by different names in the observa- tions. See also Mr. Wollaston's catalogue, zone 88°. 27 Is the same with 11 Pegasi. There are 3 observations: the first places the star in the constellation of Pegasus, the 2 latter in that of Aquarius. See also Mr. Wollaston's catalogue for this star, and others of the same kind. 65 Has not been observed by Flamsteed; yet we find it inserted in my first ca- talogue, where its relative brightness is given. It should be considered that, in the first place, several stars, of which there are no observations in the 2d volume of Flamsteed's works, and which are yet inserted in the British catalogue, such for instance as 0 and i Draconis, are well known to exist in the heavens. Now whether they were put into the catalogue from observations that are not in the 2d volume, or taken from other catalogues, it so happens that observations of them cannot be found. Therefore the want of a former observation by Flamsteed is not sufficient to prove that a star does not exist. In the next place it should be recollected, that the method used to ascertain the stars in estimating their brightness, is not so ac- curate, as to point out with great precision the absolute situation of a star; and that consequently another star which happens to be not far from the place where the catalogue points out the star we look for, may be taken for it; especially when A a. 2 180 PHILOSOPHICAL TRANSACTIONS. [ANNO 1797. there are no neighbouring stars of the British catalogue that may induce us to exert uncommon attention in ascertaining the identity of such a star. Mayer however has an observation of 65 Aquarii in his zodiacal catalogue, N° Q32, which puts the existence of the star out of doubt. 72. As the star neither was observed by Flamsteed, nor does exist, we cannot admit the remark which Mr. Wollaston in his catalogue, zone 950, has on Mayer's 939 star; where he supposes an error in declination of 3 degrees to have been com- mitted, on a supposition of its being Flamsteed's 72. 80 Requires -j- 2m in time in ra, and therefore is not the star I have given, which requires — lm 35s. — 104, Which is without ra in the British' catalogue, has 3 complete observations, page 8, 70, and 331. j4quila. — 29 Is without ra. There is but one observation of Flamsteed, page 53, which has no time. The ra is given by M. de la Lande, in Mr. Bode's Jahr- Buch for 1796, page 1 63. — 33 and 34, Which do not exist, were probably in- serted by a mistake of 1 hour in the time of one of the observations on the 2 stars 68 and 69. In the zenith-distance, page 71 of Flamsteed's observation of 69 Aquilae, for 53° read 55°. — 40 and 43, which do not exist, were probably also inserted by the same mistake of I hour in the ra of 70 and 71. Capricornus. — 1 and 2 should be g1 £2. Flamsteed calls them jso in his observa- tions, and Mayer has also adopted the same letters in his catalogue N° 821 and 822. Cygnus. — 5 Is without ra in the British catalogue; but the star has not been observed by Flamsteed. — 9 Is without ra ; Flamsteed however has a complete ob- servation of it, page 67. — 2*4 Has no ra. The time observed by Flamsteed is only doubtful in the seconds. Its ra has been given in Mr. Bode's Jahr-Buch for 1797, page 163. — 33 Has no ra. Flamsteed never observed this star; but it is 3 Cephei Hevelii. — 38 Has no ra in the British catalogue; but as the defective and only ob- servation of Flamsteed on page 75, which might be supposed to belong to 38, will agree better with 43, it follows that he never observed 38. — 68 Has no ra. There is a complete observation by Flamsteed, page 75. — 78 Has no time in Flamsteed's observations. It is N° 146 in de la Caille's catalogue. — 79 Has no ra. Flamsteed has but one observation, which is without time. Mr. Bode gives it in his Jahr-Buch for 1797? page 163. Hercules. — 24 Is the same with 51 Serpentis. — 28 Is the same with 11 Ophiu- chi. — 54. There is no observation of this star. The zenith-distance of 55 was taken twice April 8, 1 703, (instances of which we find in several other stars,) which occasioned its being inserted as 2 stars. — 63. There is no observation of this star, nor does it exist. The star of which the brightness is given in my catalogue, is at some distance from the place assigned in the British catalogue. Flamsteed observed a star, page 444, which will be N° 269 in Miss Herschel's manuscript catalogue. This, with an error in the calculation of the pd, probably occasioned the insertion of 63. And if this be the star, the pd of the British catalogue must be corrected VOL. LXXXVIl/j PHILOSOPHICAL TRANSACTIONS. 181 -}- 3°. — 7 1 Has never been observed by Flamsteed, nor does it exist. A small error, in the calculation of one of the 4 observations of 70, may have produced it. — 80 and 81 were never observed. The 2 stars v 24 and 25 Draconis, miscalled » in Flamsteed's observations, page 55 and 175, with an error of pd, accounts for the insertion of these stars. See Mr. Bode's Jahr-Buch for 1787, page 1Q4. — 93. The pd is marked : : (doubtful,) in the British catalogue; but the observation of Flamsteed, page 520, is complete. Pegasus. — 6 Is the same star with 25 Aquarii. — 1 1 Is the same star with 27 Aquarii. Additional Notes to the Stars* in the id Catalogue of the Comparative Brightness of the Stars. Aries. — 1 There is an observation of a star by Flamsteed, which being calculated with an error of 10m of time in ra., would produce 1 Arietis; we may therefore correct the British catalogue ra -f 10m, and the star will be found to exist. In Miss Herschel's manuscript catalogue it is N° U3. — 2 Is the same star with J 07 Piscium. — 38 is the same star with 88 Ceti. In 3 observations, page 85, 285, and 485, Flamsteed has called it Arietis; and on page 481 he has called it Ceti. See also Mr. Bode's Jahr-Buch for 1793, page 200. — 50; By Flamsteed'3 observation, page 273, the catalogue requires — lm in time of ra. Cassiopea. — 3. The place in the catalogue by 2 observations of Flamsteed re- quires -f 5m\ of time in ra, and + 7' of pd. — 8 Is marked : :, but has 4 com- plete observations on page 1 40, 144, 145, and 147. — 29; There is an observation of Flamsteed on page 144 which has produced this star, but the time of it re- quires a correction of -f- 6m, and it will then belong to 32. That this correction should be used, will appear when we compare this observation with another on page 213. In both places a star, which is not inserted in the British catalogue, but which is N° 384 of Miss Herschel's manuscript catalogue, was taken at the same time. On page 144 it is " Duarum infra y, versus polum, borealis. Simul fere transit, austrea;" and on page 213 we have " post transitum" for the new star, and f cum priore" for 32; and in both places the zenith-distance perfectly shows that they were the same stars: the 32d and a star south of it. And they are now both in the places where Flamsteed has observed them. — 30: Flamsteed has no observation of this star. It is y. 21 Cassiopeae Hevelii. — 33: Flamsteed observed no ra of this star. It is 9 23 Cassiopeae Hevelii. — 34 Is wrong in the catalogue. By 2 obser- vations of Flamsteed, page 144 and 521, it requires a mean correction of — 9m of time in ra. In this case my double star 111, 23, will no longer be

's, and might possibly mean to point out g 53 ; which he afterwards observed on page 27. The stars are so near together that he might easily mistake sequens for praecedens ad austrum. Flamsteed in his observations calls 58 3d j, 67 4th ^, and 70 5th 1 ; this shows that there is no authority for six ^'s. See Bode's account of the same star in his Jahr-Buch for 1788, page 171. — 71 : " April 5, 1796, 71 Cancri is J5' nearer to 78 and 15' " farther from 68 than it is placed in Atlas." — 73 and 74 have not been observed by Flamsteed, nor do they exist. How they came to be inserted, does not appear to be satisfactorily accounted for by Mr. Bode in his Jahr-Buch for 1788, page 172. He gives 4 observations of 62 and 63 Cancri ; but Flamsteed has 13, and they are all perfect, except the last on page 564. Notes to Cepheus. — 15: " October 25, 1796: 15 Cephei consists of 2 stars. Both taken together for one, by the naked eye, give 14. 15. In the telescope they are 14 — , 15 — 15." — 18 has no time in Flamsteed's observations. (* March 26, 1797. 18 is a very little preceding 19. It is I40 from 17. The stars 18, 20 and 19 are in a line which bends a little at 18 towards the preceding side." Notes to Corona Borealis. — 21, in the British catalogue requires a correction of 184 PHILOSOPHICAL TRANSACTIONS. [ANNO 1797. — 28m 21s in time of ra, and — 14' 55" in pd. In the place where it is marked in Atlas, according to the erroneous catalogue, is no star ; but very unaccountably it is also marked in its right place in the same atlas. Flamsteed has 4 complete observations of it on page 167, 445, 477> and 478. Mr. Wollaston, not being acquainted with the existence of 21 Coronae in its right place, supposes, zone 55°, that I have made a mistake in calling my double star vi. 18, very unequal ; but in his corrections he gives the place of a star, as he calls it " near v," which is the real second v of Flamsteed ; who very particularly describes it on page 167, " Duarum ad v sequens et clarior ;" and this is the double star I have given in my catalogue as 21 Coronae. Notes to Navis. — 1 : there is no observation of this star ; but in Miss Herschel's manuscript catalogue N° 92 is a star 2° more south, which has probably been cal- culated wrong, and has given occasion for its insertion ; correcting therefore the pd of 1 Navis -j- 2°, the expression of its brightness is as I have given it. — 17 : there is no observation of this star ; but if we correct the pd -+- 3°, it will then agree with N° 238 in Miss Herschel's manuscript catalogue. — 21, by Flamsteed's observation page 431, the pd of the British catalogue requires + 18'. Notes to Orion. — 12: Flamsteed never observed this star. It does not appear how it came to be inserted in the British catalogue. — 26 : Flamsteed never observed this star. An error of 20' in pd in the calculatiou of one of the 4 observations of 25 Orionis, may have occasioned the insertion of it. — 35 is marked : : in the Bri- tish catalogue ; but Flamsteed has 7 complete observations of this star ; therefore the marks : : should be out. — 63 : There is no observation of this star ; but sup- posing an error of + 2m 14s of time in ra, and of -f O' 22" in pd, it will then agree with N° 33 of Miss Herschel's manuscript catalogue. I have taken the comparative brightness of that star, supposing it to be 63. — 64 and 65 have no observation by Flamsteed ; but their insertion has been accounted for by Mr. Bode in his Jahr-Buch for 1793, page 195. He mentions Flamsteed's 2 observations on page 17 and 94. There is a 3d on page 292, which confirms what Mr. Bode says. The 64 of which I give the brightness, is not far from the place assigned to it in the British catalogue. It is N° 1 in Miss Herschel's manuscript catalogue. — 76 : There is no observation of this star. A mistake of 41" in pd in calculating one of the 4 observations of 8 Monocreotis, might occasion its insertion. XIV. An Account of the Means employed to obtain an Overflowing Well. By Mr. Benjamin Vulliamy. p. 325. In beginning to sink this well, which has a diameter of 4 feet, the land springs were stopped out in the usual way, and the well was sunk and steined to the bottom. When the workmen had got to the depth of 236 feet, the water was judged not to be very far oft', and it was not thought safe to sink any deeper. A double thick- ness of steining was made about 6 feet from the bottom upwards, and a borer of 51 inches diameter was used. A copper pipe of the same diameter with the borer VOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. 185 was driven down the bore-hole to the depth of 24 feet, at which depth the borer pierced through the rock into the water ; and by the manner of its going through, it must probably have broken into a stratum containing water and sand. At the time the borer burst through, the top of the copper pipe was about 3 feet above the bottom of the well : a mixture of sand and water instantly rushed in .through the aperture of the pipe. This happened about 2 o'clock in the afternoon, and by 20 minutes past 3 the water of the well stood within 17 feet of the surface. The water rose the first 124 feet in 11 minutes, and the remaining 119 feet in 1 hour and 9 minutes. The next day several buckets of water were drawn out, so as to lower the water 4 or 5 feet ; and in a short time the water again rose within 1 7 feet of the surface. A sound-line was then let down into the well in order to try its depth. To our great surprize the well was not found by 96 feet so deep as it had been measured before the water was in it ; and the lead brought up a suffi- cient quantity of sand to explain the reason of this difference, by showing that the water had brought along with it 96 feet of sand into the well. Whether the cop- per pipe remained full of sand or not, is not easy to be determined ; but I should rather be inclined to think it did not. After the well had continued in the same state several days, the water was drawn out so as to lower it 8 or 10 feet ; and it did not rise again by about a foot so high as it had risen before. At some days interval, water was again drawn out, so as to lower the water as before ; which at each time of drawing rose less and less, till after some considerable time it would rise no more ; and the water being then all drawn out, the sand remained perfectly dry and hard. I now began to think the water lost ; and consequently that all the labour and expence of sinking this well, which by this time were pretty considerable, had been in vain. There remained no alternative but to endeavour to recover it by getting out the sand, or all that had been done would be useless ; and though it became a more difficult task than sink- ing a new well might have been, yet I determined to undertake it, because I knew another well might also be liable to be filled with sand in the same manner that this was. The operation of digging was again necessarily resorted to, and the sand was drawn up in buckets till about 60 feet of it were drawn out, and consequently there remained only 36 feet of sand in the well : that being too light to keep the water down, in an instant it forced again into the well with the same violence it had done before ; and the man who was at the bottom, getting out the sand, was drawn up almost suffocated, having been covered all over by a mixture of sand and water. In a short time the water rose again within 17 feet of the surface, and then ceased to rise, as before. When the water had ceased rising, the sounding- line was again let down, and the well was found to contain full as much sand as it did the first time of the water's coming into it. Any further attempt towards recovering the water appeared now in vain ; and most people would I believe have abandoned the undertaking. I again considered that the labour and the expence would be all lost by so doing ; and I determined VOL. XVIII. • B Ji 186 PHILOSOPHICAL TRANSACTIONS. [aNNO 1797. without delay to set about drawing the sand out through the water, by means of an iron box made for that purpose, without giving it time to harden as before. The labour attending this operation was very great, as it was necessary continually to draw out the water, for the purpose of keeping it constantly rising through the sand, and so to prevent the sand from hardening. What rendered this operation the more discouraging was, that frequently after having drawn out 6 or 7 feet of sand in the course of the day, on sounding the next morning the sand was found lowered only 1 foot in the well, so that more sand must have come in again. This however did not prevent me from proceeding in the same manner during several days, though with little or no appearance of any advantage arising from the great exertions we were making. After persevering however for some considerable time, we perceived that the water rose a little nearer to the surface, and I began to en- tertain some hopes that it might perhaps rise high enough to come above the level of the ground; but when the water had risen a few feet higher in the well, some difficulties occurred, occasioned by accidental circumstances, which very much de- layed the progress of the work ; and it remained for a considerable time very uncer- tain whether the water would run over the top of the well or not. These difficulties being at length surmounted, we continued during several days the process before mentioned, of drawing out the sand and water alternately ; and I bad the satisfaction of seeing the water rise higher and higher, till at last it ran over the top of the well, into a temporary channel that conveyed it into the road. I then flattered myself that every difficulty was overcome ; but a few days after- wards I discovered that the upper part of the well had not been properly con- structed, and it became necessary to take down about 10 feet of brick- work. The water, which was now a continued stream, rendered this extremely difficult to ex- ecute. I began by constructing a wooden cylinder 1 2 feet long, which was let down into the well, and suspended to a strong wooden stage above, on which I had fixed 1 very large pumps, of sufficient power to take off all the water that the spring could furnish, at 1 1 feet below the surface. The stage and cylinder were so contrived as to prevent the possibility of any thing falling into the well ; and I contrived a gage, by which the men on the stage could always ascertain to the greatest exactness the height of the water within the cylinder. This precaution was essentially necessary, to keep the water a foot below the work which was doing on the outside of the cylinder, to prevent the new work from being wetted too soon. After every thing was prepared, we were employed 8 days in taking down 10 feet of the wall of the well, remedying the defects, and building it up again; during which time 10 men were employed, 5 relieving the other 5, and the 1 pumps were kept constantly at work during 1Q2 hours. By the assistance of the gage, the water was never suffered to rise on the new work till it was made fit to receive it. When the cylinder was taken out, the water again ran over into the temporary channel that conveyed it into the road. The top ofthe well was afterwards raised 1 8 inches, and constructed in such a man- VOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. 187 ner as to be able to convey the water 5 different ways at pleasure, with the power of being able to set any of these pipes dry at will, in order to repair them whenever occasion should require. The water being now entirely at command, I again re- solved on taking out more sand, in order to try what additional quantity of water could be obtained. I cannot exactly ascertain the quantity of sand taken out, but the increase of water obtained was very great ; as instead of the well discharging 30 gallons in a minute, the water was now increased to 46 gallons in the same time. XV. Observations of the Changeable Brightness of the Satellites of Jupiter, and of the Variation in their Apparent Magnitudes ; with a Determination of the Time of their Rotatory Motions on their Axes. To which is added, a Measure of the Diameter of the Second Satellite, and an Estimate of the Comparative Size of all the Four. By Win. Herschel, LL.D., F.R.S. p. 332. It may be easily supposed, when I made observations on the brightness of the 5th satellite of Saturn, by way of determining its rotation on its axis, and found that these observations proved successful, that I should also turn my thoughts to the rest of the satellites, not only of Saturn, but likewise of Jupiter, and of the Georgian planet. Accordingly I have from time to time, when other pursuits would permit, attended to every circumstance that could forward the discovery of the rotation of the secondary planets ; especially as there did not seem to lie much difficulty in the way. For since I have determined, by observation, that the 5th satellite of Saturn is in its rotation subject to the same law that our moon obeys, it seems to be natural to conclude that all the secondary planets, or satellites, may probably stand in the same predicament with the two I have mentioned ; conse- quently a {ew observations that coincide with this proposed theory, will go a good way towards a confirmation of it. I had another point in view when I made the observations contained in this paper. It was an attempt to avail myself of the abundant light and high powers of my various telescopes, to examine the nature and construction of the bodies of the satellites themselves, and of their real mag- nitudes. Here phenomena occurred that will perhaps be thought to be remarkable, and even inconsistent or contradictory. So far from attempting to lessen the force of such animadversions, I shall be the first to point out difficulties, in order that future observations may be made to resolve them. Perhaps it would have been better to delay the communication of these observa- tions, till I had continued them long enough to be able to account for things which at present must be left doubtful. But as, in final conclusions to be drawn from astronomical observations, we ought to take care not to be precipitate ; so on the other hand I am perhaps too scrupulous in satisfying myself, and should pro- bably require the observations of several years before I could venture to be decisive. It will also be seen by the dates of the first observations, that a further delay in the communication cannot be adviseable , since much information may possibly be b b 2 188 PHILOSOPHICAL TRANSACTIONS. [ANNO 1797. gained by throwing open, to other observers, the road it will be eligible to take for a satisfactory investigation of the subject , especially as we have reason to congratulate ourselves on the spirit of observation, and increase of large instruments, that seem to have taken place in various parts of Europe. The observations from my jour- nals are as follow. OBSERVATIONS. j4 remarkable conjunction of two satellites of Jupiter. — May 14, 1790, 1 lh 30m 10s, correct sidereal time. The 2d and 3d satellites of Jupiter are so closely in conjunction, that with a 7-feet reflector, charged with a magnifying power of 350, I cannot see a division between them. At 1 lh 34m 10s, the shadow of the 1st sa- tellite is still on the disc of the planet. Intenseness of light and colour of the satellites. — July 19, 1794, 1 7h 12m 47s, 7-feet reflector: the 1st satellite of Jupiter is of a very intense bright, white, shin- ing light. It is brighter than the 2d or 4th. I speak only of the light, and not of the size. — The colour of the 4th satellite is inclining to red. In brightness it is very nearly, but not quite equal to the 2d. — 10-feet reflector, power 170 : the 3d satellite is just gone upon the body; before it went on^ it appeared to be smaller' than usual. — The 2d satellite is of a dull, ash-colour ; not in the extreme, but ra- ther inclining to that tint. — July 21, 1794, l6h 56m 45s; 10-feet reflector; power 170 : the 3d satellite of Jupiter is round, large, and well defined. It is very bright, and its light is very white. — The 4th satellite is also round, large, and well defined. I estimate its magnitude in proportion to that of the 3d satellite to be as 4 to 5. Its light is not white, but inclined to orange. Brightness and diameter distinguished. — July 26, 1794, I7h 14m41s; 10-feet reflector; power 170 : The 4th satellite is very dim : it is of a pale, dusky, reddish colour. The 2d satellite is of a bright, white colour. The 3d satellite is very bright, and white. The 1st satellite is very brilliant, and white. At 17h 22ra 41s, the magnitudes with 240, were thus : the 3d satellite is the largest : the 2d satel- lite is the smallest. With 300, the 4th satellite is a very little larger than the 2d, though less bright. The 1st satellite is larger than either the 4th or 2d. With 400, the order of the magnitudes is 3 1 4 2. With the same power, the order of the light is 3 1 2 4. Diameter of the second satellite by entering on the disc of the planet. — July 28, 1794, I7h25m40s; 10-feet reflector; power 170: the 2d satellite is nearly in contact with the following limb of Jupiter. — I7h 29m 40s, it seems to be very near the contact : with 300, very near the contact. — I7h 30m 40s, it seems to be in contact: it is brighter than that part of Jupiter where it enters. — I7h 31m 40s, it is more than half entered. — I7h 33m 40', it seems to be nearly quite en- tered: its superior brightness makes it seem protuberant. — I7h 34m 40s, it is cer- tainly quite entered. — 17h 35m 25s, I see a little of the disc of Jupiter on the out- side of the satellite, equal to about \ of its diameter. — 17h 39m 40s, the 3d satellite is very bright, and of its usual colour. — The 4th satellite is faint, and also of its VOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. ] 89 usual colour. — The 1st satellite is very bright, and its light is of the usual in- tenseness. The magnitudes with 300. — The diameter of the 4th seems to be to that of the 3d, as 2 to 3 ; or perhaps more exactly, as 3 to 5. — The diameter of the 4 th satel- lite exceeds that of the 1st a very little. — With 400. With this power the diameter of the 4th satellite certainly exceeds that of the 1st. — The diameter of the 4th is to that of the 3d, as 3 to 5. July 30, 1794, 19h lm 37s, 10-feet reflector; power 300: the 4th satellite of Jupiter is a little larger than the 1st: it is of its usual colour. The 2d is less than the 1st. The 3d is larger than the 4th. July 31, 1794, 17h 18m38s; 10-feet reflector; power 17O: the 4 satellites of Jupiter are very favourably placed for my purpose. The 1st is less bright than the 2d: it is a very little larger than the 2d: the difference in the size is but barely visible. The light of the 2d is very intense and white. The light of the 3d is very intense and bright. The light of the 4th is dull ; and seems to be inferior to the usual proportion it bears to the other satellites. — At 18h 38m 38s; with 300; the 4th satellite is larger than the 1st; the 2d satellite is a little larger than the 1st, or at least equal to it; the 3d is undoubtedly the largest. The order of the mag- nitudes therefore is, 3 4 2 1 . My brother, Alexander Herschel, looked at the sa- tellites, and estimated the order of their magnitudes exactly the same; though he was not present when I made the foregoing estimations. August 1, 1794, 17h 38m 37s; 10-feet reflector; power 170: the light of all the 4 satellites is very brilliant, the evening being very fine. — With 300, the north- most and farther of the 2 satellites which are in conjunction, is the smaller: I sup- pose it to be the 2d. The southern and nearer of the 2 satellites in conjunction, is the next in size; I suppose it to be the 1st. The 4th satellite is a little larger than the larger of the 2 satellites which are in conjunction; but the difference is only visible with a great deal of attention. The 3d satellite is much larger than the 4th. August 9, 1794, I7h 50ra 32s; 10-feet reflector; power 170; the light of the 1st satellite is very intense and white. The light of the 2d satellite is also pretty intense and white. The light of the 3d satellite is neither so intense nor so white as that of the 1st. The light of the 4th is dull and of a ruddy tinge. With 300 and 400, the 2d is the least, and the 3d is the largest. I am in doubt whether the 4th or the 1st is largest; with 600, I suppose the 1st to be larger than the 4th. September 30, 1795, 20h I5m 17s; 7 -feet reflector ; power 210; order of the magnitudes of the satellites of Jupiter 3-2.1,4; power 110; 3-2,1 .4; with 460, 3-2,1,4. October 2, 1795, 20h 18m 22s; 7-feet reflector; power 287; Jupiter's satellites 3 --2 1,4. The 2d and 3d satellites are not yet in conjunction. — At 20h 43m 22s. The conjunction between the 3d and 2d satellites is past. The distance be- tween them is now one diameter of the 3d. August 18, 1796, 18h47m2Js; 7-feet reflector; power 287; the 4th satellite is 19° PHILOSOPHICAL TRANSACTIONS. [ANNO 1797. less bright than the 1st; though the latter is so near the planet as to have its light overpowered by Jupiter, while the 4th is at a great distance; I mean light or bright- ness, not magnitude. The 1st is very bright. September 15, 1 796, 19h 25ra 25'; 10-feet reflector; power 300; the 2d satel- lite of Jupiter is a little less than the 1st. The 3d is much larger than any of the rest. — With the power 600 the difference in the magnitude of the 1st and 2d sa- tellites, with this power, is pretty considerable. September 21, 179^» 19h 24m 5*; 10-feet reflector; power 600; the shadow of the 1st satellite is on one of the dark belts of Jupiter. In order to use very high powers with this telescope, I tried it on the double star f Aquarii with 1200. The air is very tremulous, but I see now and then the 2 stars of this double star very well defined. With the same power, the satellites of Jupiter are very large, but not so well defined as the above star. The brightness of the satellites compared to the belts and disc of the planet. — The 1st satellite, which is lately come off the southern belt, is nearly of the same brightness with that belt; power 600. With 400, it is nearly as bright as the brighter part of the planet, or rather a mean between the belt and the planet. The 2d satellite is considerably bright ; its colour is whiter than that of the 1st; it is however not so white as the colour of the bright part of Jupiter. The colour of the 4th satellite is as dingy as that of the belt; very much less bright and less white than that of the 2d. The brightness of the 3d satellite is not intense; its colour however is white, though not so white as the bright part of the planet. September 24, 1796, 20h 55m 24s; 10-feet reflector; power 000; the 1st sa- tellite of Jupiter is very bright, and of a white colour; it is also very large. The 2d satellite is faint and bluish; its light is not much brighter than that of the belt. The 3d satellite is pretty bright; its light is whitish; it seems to be comparatively less than it ought to be; or rather, its apparent smallness is owing to the uncommon largeness of the 1st. The 1st satellite, with 200, compared to the 3d, is propor- tionally larger than I have seen it before. September 30, 1796, 20h 8m 4s; 10-feet reflector; power 000; the satellites of Jupiter are well defined, and the night is beautiful. The 3d satellite, in proportion to the 1st, is much larger than it was September 24; I ascribe the change to an apparent diminution of the 1st. — At 20h 30m 4s, the 1st satellite is evidently less in proportion to the 3d, than it was September 24. The 2d satellite is considerably bright; its light is whitish; much brighter than the belt, but not so bright as the bright part of the disc; its magnitude is less than that of the 4th; but its light is considerably superior. The 3d satellite is remarkably well defined; its light is con- siderably brighter than that of the belts. The magnitude of the 1st satellite exceeds that of the 2d; it is nearly equal to that of the 4th. — At 22h 58m 4s, appearances as before. October 15, 1796, 2lh 23m42s; 10 feet reflector; power 600; the 2d satellite is uncommonly bright; its apparent magnitude is also larger than usual. The 4th VOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. igi satellite is very faint; it is not brighter than the belt, but is of a bluish, ruddy co- lour. The apparent magnitude of the 2d satellite, after long looking, is very nearly equal to that of the 1st; but at first sight it seems to be larger, owing to its superior brightness. The apparent diameter of the 2d satellite is certainly larger than that of the 4th. — At 23h 55m42s, the light of the 1st satellite, compared to that of the 2d, is considerably increased since the last observation. It is now nearly as bright as the 2d. October 16, 17 96, 23m 49s; 10-feet reflector; power 600; the 1st, 2d, and 3d satellites of Jupiter seem all considerably bright. The 3d is much larger than the 1st, and the 1st a little larger than the 2d. The intensity of the light seems to be pretty equal in all the 3; that of the 2d however is perhaps a little stronger than that of the 1st; for, notwithstanding its apparent less diameter, it seems to make as strong an impression as the 1st. October 25, 1796, 21h 44m 48s; 10-feet reflector ; power 600; the 1st satellite of Jupiter, compared to the 3d, is small. The 3d satellite is bright and large. The 2d is brighter than the 1st. Compared to its usual brightness and magnitude, it is very bright and small. The 1st satellite, compared to its usual brightness and magnitude, is faint and small. The air is so tremulous that the power of 000 is too high, and the necessary uniformity required in these observations will not per- mit a lower to be used. Perhaps one of 400 might be more generally employed; and it may be proper to use it constantly. November 3, 1796, 23h 55m47s; 10-feet reflector; power 600; the 4th satellite of Jupiter is large and bright. The 3d satellite is large and bright. The 1st satellite is pretty small, and not very bright. The 2d satellite is small, and consi- derably bright. The brightness and magnitude of each satellite refer to its own usual brightness and magnitude. Before we can proceed to draw any conclusions from these observations, we ought to take notice of many causes of deception, and of various difficulties that attend the investigation of the brightness of the satellites. The difference in the state of the atmosphere between 2 nights of observation, cannot influence much our esti- mation of the brightness of a satellite, provided we adopt the method of compa- rative estimations. If we endeavour by much practice to fix in our mind a general ideal standard of the brightness of each satellite, we shall find the state of the at- mosphere in different nights very much disposed to deceive us; but if we learn to acquire a readiness of judging of the comparative brightness of each satellite with respect to the other 3, we may arrive at much more precision, since the different disposition of the air will nearly affect all the satellites alike. But here, as we get rid of one cause of deception, we fall under the penalty of another. The situation of those very satellites to which we are to refer the light of the satellite under esti- mation, being changeable, permits us no longer to trust to their standard, without a full scrutiny of the causes that may have produced an alteration in them. In the foregoing observations it will also be seen, that I attempted to compare the intense- 192 PHILOSOPHICAL TRANSACTIONS. [aNNO 1797* ness of the light of the satellites with the different brightness of the disc of Jupiter ; but these endeavours will always fail, on account of the little assurance we can have that the parts of the disc, setting aside its quick rotation, will remain for any time of the same lustre. A very material difficulty arises from the magnifying power we use in our esti- mations. If it be a low one, such as for instance 180 (for a lower should not even be attempted), then we run the risk of being disappointed in bright nights by the sparkling of the brilliant light of the satellites. Besides, we cannot then see the bodies of them, and judge of their comparative magnitude, with the same power that we view their light. If we choose a higher magnifier, we shall be often dis- appointed in the state of the atmosphere, which will of course occasion an inter- ruption in the series of our observation, of which the regular continuance is of the greatest consequence. If we change our power according to the state of the at- mosphere, we introduce a far worse cause of confusion; for it will be next to im- possible to acquire, for each magnifying power, an ideal standard of comparative brightness to which we can trust with confidence. If the magnitudes are not attended to, and carefully contra-distinguished from the intenseness of light, we shall run into considerable error, by saying that a satellite is large, when we mean to express that it is bright. It is so common to call stars that are less bright than others, small, that we must be careful to avoid such ambiguities, when the condition of the satellites is under investigation. Nor is it possible to throw the size and light into one general idea, and take the first coup d'ceil in looking at them, to decide about the general impression this com- pound may make. When our attention is forcibly drawn by a considerable power to the apparent size of the satellite we are looking at, its brightness can no longer be taken in that general way, but must be abstracted from size. Let us now see what use may be drawn from the observations I have given. It appears in the first place very obviously, that considerable changes take place in the brightness of the satellites. This is no more than might be expected. A variegated globe, whether terraqueous like the earth, or containing regions of soil of an un- equal tint, like that side of the moon which is under our inspection, cannot, in its rotation, present us with always the same quantity of light reflected from its surface. In the next place, the same observations point out what we could hardly expect to have met with; namely, a considerable change in the apparent magnitude of the satellites. Each of them having been at different times the standard to which another was referred, we cannot refuse to admit a change so well established, sin- gular as it may appear. The first of these inferences proves that the satellites have a rotatory motion on their axes, of the same duration with their periodical revolutions about the primary planet. The 2d either shows that the bodies of the satellites are not spherical, but of such forms as they have assumed by their quick periodical and slow contemporary rotatory motions, and which forms in future may become a subject for mathematical VOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. 1Q3 investigation ; or it may denote, in case geometrical researches should not counte- nance a sufficient deviation from the spherical form, that some part of the discs of these satellites reflects hardly any light, and therefore in certain situations of the satellite makes it appear of a smaller magnitude than in others. Here then we see evidently that a considerable field for speculation, as well as observation, is opened to our view ; and almost every attempt to enter on the work must seem premature, for want of more extended observations. However, from those that have been given, such as they are, I will show how far we may be authorised to say, that the satellites revolve on their axes in the same time that they perform a periodical revo- lution about the planet. I shall take the usual method of throwing the observations of each satellite into a graduated circle. The zero of the degrees into which I suppose it divided, is in all observations assumed to be in the place of the geocentric opposition. In order to bring these observations to the circle, the places of the satellites have been cal- culated from my own tables of the mean motion in degrees, and according to epochs continually assumed from the geocentric conjunctions pointed out in the configurations of the Nautical Almanac; and the nearest of these conjunctions have been always used. This method is fully sufficient for the purpose, as greater precision in the calculation is not required. The observations extend from July ] 9, 1794, to November 3, 1796; and therefore include a period which takes in 470 rotations of the 1st satellite; 234 of the 2d; 1 1 6 of the 3d; and 50 of the 4th; that is, provided we admit that these rotations are performed in the same time as the satellites revolve in their orbits. In the following table are the calculated places of the satellites; the correct sidereal times, given with the observations, having been turned into mean time. Positions of the 4 Satellites of Jupiter at the Time of the Observations. Time of observation. 1794. 9h 8 8 10 July 19 July 21 July 26 July 28 July 30 July 31 8 Aug. 1 .... 8 Aug. 9 8 1795. Sept. 30 7 Oct. 2 7 21r 57 56 59 27 40 56 42 37 32 I 11 in IV 127° 346° 179° 46° 278 89 124 333 169 205 171 176 270 248 231 25 13 292 59 118 60 312 265 221 111 334 83 310 152 138 294 62 219 100 341 264 319 143 Time of ot »servat ion. 1 11 in IV 1796. Aug. 18d .. .. 8h 21m 115 0 0 191° Sept. 15 .. 7 44 36 328 198 Sept. 21 .. .. 7 19 172 214 138 210 Sept. 24 . . . 8 38 74 163 305 275 Sept. 30 . . . 7 27 206 46 244 36 Oct. 15 ... . 7 44 28 130 5 Oct. 15 ... . 10 15 49 Oct. 16 .. .10 39 256 243 33+ Oct. 25 .. . 7 25 261 72 59 Nov. 3 ... • 9 0 306 270 151 58 It will be necessary now to explain in what manner, with the assistance of this table, the observations of the brightness and magnitudes of the satellites have been reduced to the expressions they bear in the 4 circles of the figures 1 , 2, 3, 4, pi. 4. By way of uniformity I judged it would be best to reduce the estimations of mag- nitude to those of brightness ; as it may be justly supposed that when a satellite is vol. xviii. C c 1()4 PHILOSOPHICAL TRANSACTIONS. [ANNO 1797. at any given time larger in proportion to another than it was at another time, it will also be brighter than it was at that other time, due regard being had tQ the light of the satellite to which its magnitude has been compared. To manage the space allotted to the figure advantageously, I have used the abbreviations formerly em- ployed in my catalogue of nebulae, vb, cb, b, pB, pF, f, cf, vf, for all the gra- dations of light that are necessary to express the brightness of the satellites at the time of observation. It will be easily remembered that b and f mean bright and faint; and p, c, v, stand for pretty, considerably, and very. Now, when the observation mentions the brightness of the satellite, I place it in the figure as it is given. In that of the first, for instance, July 19, 1794, we find the satellite called very bright; I therefore set down in fig. 1, at 127°, vb. But where the brightness is not expressed, I have recourse to the comparative magnitude, if that can be had. By fig. 3, it appears that the 2d satellite is less subject to a change of brightness than either the 1st or 4th: it becomes, for that reason, a pretty good standard for the light of these other satellites. Therefore, in the observation of October 2, 1795, for instance, where the 1st satellite is de- scribed as undoubtedly less than the 2d, I set down very faint, or vf, at 341° of the circle of fig. 1 ; for in the observation of July 19, before-mentioned, when the satellite was called very bright, it was at the same time described as undoubtedly larger than the 2d. In this case, as regard must be had to the relative state of the satellite we refer to, the 4 figures will assist us in determining the condition of the light of the satellite we wish to admit as a standard. In reducing the 2d satellite to the circle, I have generally used a reference to the magnitude of the 1st, where marks of brightness were wanting; and sometimes also to the magnitude of the 4th, and even of the 3d. The 3d satellite can hardly be ever compared to any but the 2d in magnitude; and this only in its degree of excess. The magnitude of the 4th satellite has been generally compared with that of the 1st; and also sometimes with that of the 2d. To make an application of the contents of the figures, will now require little more than a bare inspection of them. The 1st satellite appears evidently to have a rotation on its axis that agrees with its revolution in its orbit. It cannot be supposed that, in the course of 470 revo- lutions, all the bright observations could have ranged themselves in one half of the orbit, while the faint ones were withdrawn to the other. The satellite appears in the middle of the duration of its brightness, when it is nearly half way between its greatest eastern elongation, in the nearest part of its orbit; or when advancing towards its conjunction. I have pointed out this circumstance by a division with dotted lines, and the words bright and faint, inserted within the circle, fig. 1 1 This satellite therefore revolves on its axis in ld 18h 26m.6. The 2d satellite, though much less subject to change, on account, as we may suppose, of having only a small region on its body which reflects less light than the rest; has nevertheless its rotation directed by the same law with the 1st. It will VOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. jg5 hardly be necessary to take notice of a single deviation which occurs at 163°, fig. 2; as, from the proximity of the satellite to the conjunction, a mistake in the esti- mation may easily take place. I generally made it a rule not to make allowance for the influence of the superior light of the planet ; but it seems that we can hardly abstract sufficiently on such occasions. Two similar cases occur, in fig. 3, at 179; and fig. 4, at 5°. It is indeed not impossible but that occasional changes, on the bodies of the satellites themselves, may occasion some temporary irregularity of their apparent brightness: it will however not be necessary to make such an hypo- thesis, till we have better authority for it. The brighter side of this satellite is turned towards us when it is between the greatest eastern elongation and the con- junction. It revolves consequently on its axis in 3d 18h I7m.g. The 3d satellite suffers but little diminution of its brightness, and is in full lustre at the time of both its elongations. It is however not impossible but that, after having recovered its light, on the return from the opposition, it may suffer a 2d defalcation of it in the nearest quadrant about half way towards the conjunction. The 2 independent observations at 151 and 152°, fig. 3, seem to give some sup- port to this surmise. It revolves on its axis in 7d 3h 5Qm.6. The 4th satellite presents us with a few bright views when it is going to its oppo- sition, and on its return towards the greatest eastern elongation ; but otherwise it is generally overcast. Its colour also is considerably different from that of the other 3; and it revolves on its axis in 10d 18h 5m.l. It will not be amiss to collect into one view, all the observations that relate to the colour of the satellites. The 1st is white; but sometimes more intensely so than at others. The 2d is white, bluish, and ash-coloured. The 3d is always white; but the colour is of different intensity, in different situations. The 4th is dusky, dingy, inclining to orange, reddish and ruddy at different times; and these tints may induce us to surmise that this satellite has a considerable atmosphere. I shall conclude this paper with a result of the observation of the diameter of the 2d satellite, taken by its entrance on the disc of the planet, July 28, 17 Q4 and marked in fig. 2, at 1760. The duration by the observation is fixed at 4 mi- nutes; in which time it passes over an arch in its orbit of 16' 52ff.Q. Now as its distance from the planet is to its distance from the earth, so is 16' 52/;. 9 to the diameter of the satellite; or the mean distance of the 2d satellite may be rated, with M. de Lalande, at 2' $7",- or 177". Then putting this equal to radius, we shall have the following analogy : Radius is to 177//» as the tangent of l6' 527/.g is to the angle, in seconds, which the diameter of the 2d satellite subtends when seen from the earth. And by calculation, this comes out 0'/.87 ; that is less than _%. of a second. I have not been scrupulously accurate in this calculation, as the real distance of Jupiter at the time of observation should have been computed, whereas I have con- tented myself with the mean distance. Nor am I very confident that the angle of the greatest elongation, admitted to be 2' 57", is quite accurate; but I judged it c c 2 1q6 philosophical transactions. [anno 1797. unnecessary to be more particular, because the time of my observation in the beginning of the transit on the disc, I find was only taken down in whole minutes of the clock. The end however is more accurately determined, by the observation which was made 45s after the immersion; when a part of the disc, equal to about -J- of the diameter of the satellite, is said to be visible. It seems that observations of this kind, made with very good telescopes, charged with high powers, are capable of great precision. For the remark that a margin of Jupiter, equal to about -J- of the diameter of the satellite, became visible in 45s of time, adds great support to the accuracy of the observation of the foregoing 4 minutes ; and at all events it is evidently proved, from the whole of the entrance on the disc, that the diameter of the satellite is less, by one half at least, than what from the result of the measures of former observers it has been supposed to be. A method has also been used, of deducing the diameter of the satellites from the time they employ to immerge into the shadow of the planet ; but this must be very fallacious, and ought not to be used. I should not pass unnoticed the apparent magnitude of the satellites. The ex- pressions that have been given of them may be collected into the following narrow compass: 1,4,2 4;1 3 — , 4 ; 1 — 2 4,2,1 3 4;1;2 1,4,2 3 — 2,1,4 3 2—1,4 1T24 . — 2 1 ; 2 — 4 3 1,2 2—1. From which we may conclude, that the 3d satellite is considerably larger than any of the rest; that the 1st is a little larger than the<2d, and nearly of the size of the 4th; and that the 2d is a little smaller than the 1st and 4th, or the smallest of them all. XVI. Further Experiments and Observations on the Affections and Properties of Light. By Henry Brougham, Jun. Esq. p. 352. I am first to unfold a new, and I think curious property of light, that may be indeed reckoned fourfold, as it holds, like the rest, equally with respect to refrac- tion, reflexion, inflexion, and deflexion; thus preserving entire the same beautiful analogy in these 4 operations, which we have hitherto remarked. I shall then consider several phenomena connected either with this, or with the properties be- fore described, and of which they afford some striking confirmations. I. Observation 1. The sun shining strongly into my darkened chamber, I placed, at a small hole in the window-shutter, a prism with its refracting angle (of 65°) upwards, so that the spectrum was cast on a chart placed at right angles to the incident rays, and 4 feet from the prism. In the rays, parallel to the chart, and 2 feet from it, I placed a pin, whose diameter was ^ of an inch, and fixed it so, that the axis of its shadow on the spectrum might be parallel to the sides of the spectrum. A set of images by reflexion was formed similar to those described for 179^j all inclining to the violet; but what I chiefly attended to at present was their shape. I had always observed that the part formed out of the red-making VOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. ] Q7 rays was broadest, and that the other parts diminished in breadth regularly towards the violet. I now delineated 1 or 2, at about 3 inches from the shadow; and though, from the pin's irregularities, the sides were by no means smooth, yet the general shape was in every pin, and with every prism used, nearly as represented in fig. 5, pi. 4, divided in the direction ra, according to the colours of the spectrum in which they were formed; rob a was red, and the broadest; that is, ra was broader than ob, the confines of the red and orange; and gdev was the violet, narrowest of all. Observ. 2. Between the pin and the prism, -^ of an inch from the pin, was placed a screen, through a small hole in which, of twice the pin's diameter, the rays of the spectrum passed, and were reflected into images by the pin; these were pretty distinct and well defined, when received on a chart 4- a foot from the pin. They were oblong, having parallel sides and confused ends; they were wholly of the colour whose rays fell on the pin, unless when the white, mixed with those at the confines of the yellow and green, caused the images to be of all the colours. When the prism was turned round on its axis, so that different rays fell on the pin, the images changed their sizes as well as their positions; they were largest when red, and least when violet. Observ. 3. In case it may be thought that the sides of the hole, through which the rays passed in observation 2, by inflecting, might dispose them, before inci- dence, into beams of different sizes, I removed the screen, and placed the pin horizontally, the axis of the shadow being now at right angles to that of the pris- matic spectrum ; and moving the prism on its axis, again I observed the contrac- tion and dilatation of the images by reflexion, though now they were rather less distinct, from the greater size of the incident beam; and to show that there was both a change of size and of place, without any manner of deception, I placed one leg of a pair of compasses in a fixed point of the spectrum, and the other in the middle point of an image formed by the violet -making rays. The prism being then moved till the image became red, I again bisected it, and found its centre considerably beyond the point of the compasses, which was indeed evidently much nearer one end of the image than the other; besides, that the red image, when measured, was longer than the rest ; and this satisfied me that there were 2 changes, one of place with respect to the fixed point, the other of size, with respect to the centre of the image. Lastly, as far as I could judge, the dilatation and con- traction appeared even and uniform. Observ. 4. I remarked that the fringes or images, by flexion, were always in- creased in size when formed out of red-making rays, and were less in every other colour, and least in violet, besides being moved farther from the edge of the shadow in the former rays than in the latter; and this agrees with an observation of Sir Isaac Newton, as far as he tried it, which was with respect to deflexion. In making several experiments with prisms, I hit on a very remarkable confirmation of this. I observed on each side of the spectrum 4 or 5 distinct fringes, like the images by reflexion, coloured in the order of the spectrum, but quite well defined 1Q8 PHILOSOPHICAL TRANSACTIONS. [ANNO 17 Q7* at the edge, and even pretty distinct at the end ; they were also much narrower than those images, but like them they inclined much to the violet, and were broadest in the red, becoming narrower by degrees, and narrowest of all in the violet. I moved the prism, and they disappeared ; but when the prism was brought back to its former position, they also returned. I then observed the prism in open light, and saw that it had veins, chiefly opaque and white, running through it, and that there were several of these in the place where the light passed when the prism was held as before. But in case the inclination and shape of these images might be owing to the irregular order in which the veins were laid, I held another prism, which happened to have parallel veins ; in many positions of this the fringes or images returned, not indeed always so regular nor always of the same kind ; for some were confused and broader, formed, as I concluded from this and their posi- tion, by reflexion ; others, made by transparent veins and air-bubbles, were also irregular, but inclined to the red, the violet being farthest from the perpendicular, and these were obviously caused by refraction ; yet all agreed in this, that they were broadest in the red, and narrowest in the violet parts. Observ. 5. I held, in the direct rays of the sun, at -f an inch from the small hole in the window-shutter, a glass tube, free from scratches and opaque veins, but like most glass that is not finely wrought, having its surface of a structure somewhat fibrous. When this tube was slowly introduced into the light, and so held that none of the rays might be refracted, a streak, chiefly white, was seen, similar in shape and position to those described in the former paper. When narrowly in- spected, it was found to contain many images by reflexion in it. But these were much diluted by the abundance of white light, reflected without decomposition in the manner above-mentioned. This streak lay wholly on one side of the tube ; but I moved the tube onward a little, and another streak darted through the shadow, and extended all round on both sides : and now, when the tube was in the middle of the rays, there were 1 streaks on both sides, one a little separated from the other and continued through the shadow, the other on each side of the shadow ; the former was evidently produced by refraction ; it contained many images very like those by reflexion, only more vivid in the colours, which were all in the inverted order, the violet being outermost, and the rest nearest the point of incidence. Images similar to these are also producible on the retina, as mentioned before. Observ. 6. I now placed a prism at the hole, and made the same images by re- fraction, out of homogeneal light. These inclined to the red, not, like images by reflexion, to the violet ; but they were broadest in the red, and narrower towards the violet parts. In short, when viewed beside the images by reflexion, except in point of brightness and inclination, they differed from them in no respect. The first 3 experiments show, that when homogeneal light is reflected, some rays are constantly disposed into larger images than others are, that is, into images more distended in length, though of the same breadth. The 4th experiment shows, that trie same takes place when light is inflected and deflected ; and the last 2 show, VOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. \QQ that the same happens when the rays are refracted in a way similar, or analogous, to that in which the other images were produced by reflexion and flexion. We are now to show, that this difference of size is not owing to the different re- flexibilities and flexibilities of the rays. In order to this, we shall both demonstrate, and then prove by experience, " that inflexion and deflexion do not decompound heterogeneous rays, whose direction is such that they fall on the bending body." In fig. 6, let ab be the body ; gh, ef, cd, the limits of its spheres of deflexion, in- flexion, and reflexion, respectively ; and let ip be a white ray of direct light enter- ing at p the sphere of deflexion : through p draw lk at right angles to gh ; ip will be separated into pr red, and pv violet, and the 5 other colorific rays according to their deflexibilities ; at r and v draw the perpendiculars st and qo ; then the alter- nate angles prt, rpl ; and pvq, vpl, are equal each to each. But trp and avp are the angles of incidence, at which the red and violet enter the sphere of inflexion: and rpl, vpl are the angles of deflexion of the red and the violet ; therefore the difference of the latter 2, that is rpv, is likewise the difference of the 2 former. Suppose this difference equal to nothing ; or that pv and pr are parallel ; then rRs, the angle of the red's inflexion, will be less than wo, the angle of the violet's in- flexion, by the angle rpv : when not evanescent, add rpv to trs ; then trs will be equal to wo : that is, the divergence will be destroyed, and the rays enter the sphere of reflexion, parallel and undecompounded. It is evident therefore, that the effect arising from the different deflexibilities of the rays is destroyed by the equal and opposite effect produced by their different inflexibilities ; and the same thing may in like manner be shown to happen in the return of the rays from the body after reflexion. But let the rays be so reflected, that they shall pass by the body without entering any more than one sphere of flexion ; then they will be separated by their flexibilities, as we before described. It appears then, that if the rays of light were not differently reflexible, flexion could never produce the coloured images, by separating the compound light. And indeed this may be easily proved by fact. At 144 feet from the bending body, the greatest fringes by flexion are only half an inch in length, whereas the 4th or 5th images by reflexion are above half an inch at 1 foot from the reflecting surface : the one sort is therefore more than 144 times more distended than the other, whereas the flexion could, at the very farthest, only double them. Also the distinctness, and brightness, and regularity of the colouring, are quite different in the 2 cases ; the supposed cause would neither account for the order of the colours, nor for their absence in common specular reflexion, and refraction through two prisms joined together with their angles the contrary ways. Lastly, if we suppose the images to be produced by flexion, and then reflected from the body, it would follow, that light incident on a prism should be decompounded, formed into several coloured images, and then re- fracted, the violet being least and the red most bent ; all which is perfectly the re- verse of what actually happens. I have multiplied the proof of this proposition 200 PHILOSOPHICAL TRANSACTIONS. [ANNO 179?. perhaps beyond what is necessary ; but its great importance to the whole theory I hope will plead my excuse. Let us now suppose that a homogeneal beam passes through the spheres of flexion : it will follow that no divergence can take place from the bending power of the body ; so that we have only to estimate the effect produced by the reflexion, and to inquire whether the different reflexibilities of the rays can cause the images to vary their sizes according as they are formed by different rays. In fig. 7, let ab be the body, cd the limit of its sphere of reflexion, and ip a beam of homogeneal rays, as red, incident at p and reflected to e, forming there the image Rr. It is evident that the greater reflexibility of the rays ip can only alter the position of the centre of Rr, making it nearer the perpendicular than the centre of an image formed by any other rays would be. But the greater length of Rr shows that a greater quantity of rays is reflected, or that the same quantity is spread over a greater space, and that in the following way. Let ifH be a beam of violet-making rays entering abcd, and reflected so as to form the image rv. The force exerted by ab decreasing according to some law (of which we are as yet ignorant) as the distance increases, is not suf- ficient to turn the rays back till they have come a certain length within abcd. But for the same reason it turns back all that it does reflect before they come nearer than a certain distance ; between these 1 limits therefore the rays are turned back. But the limits are not the same to all the rays ; some begin to be turned at a greater distance from the body than others, and consequently are reflected to a greater dis- tance from the middle ray of the incident beam. Thus if ifH be changed to a red- making beam, it begins to be turned back at f. and the rays farthest from ab are reflected to r instead of to v, where they fell when ipfi was violet- making ; not but that the same quantity of rays is reflected, the only difference is, that the most re- flexible are reflected farthest from the body by their greater reflexibility, and farthest from each other by this other property. Exactly the same happens in the case of refraction, mutatis mutandis ; but there seems to be a slight variation in the man- ner in which the different rays are disposed into images of different sizes by flexion. In this case also the bending body's action reaches farther when exerted on some rays than when exerted on others : but then, the direction of the rays not passing through the body, those which are farthest off and at too great a distance to be bent, never coming nearer, are not bent at all ; and consequently as the least flexible rays are in this predicament at the smallest distance, and the most flexible not till the distance is greater, the images formed out of the former must be less than those formed out of the latter. This difference in the way in which the phe nomenon appears, does not argue the smallest difference in the cause : it only fol- lows from the different position of the rays, with respect to the acting body, in the 2 cases. I infer then from the whole, that different sorts of rays come within the spheres of flexion, reflexion, and refraction, at different distances, and that the actions of bodies extend farthest when exerted on the most flexible. It may perhaps be VOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. 201 consistent with accuracy and convenience to give a name to this property of light ; we may therefore say, that the rays of light differ in degree of refrangity, reflexity, and flexity, comprehending inflexity and deflexity. From these terms (uncouth as, like all new words, they at first appear) no confusion can arise, if we always re- member that they allude to the degree of distance to which the rays are subject to the action of bodies. I shall only add an illustration of this property, which may tend to convey a clearer idea of its nature. Suppose a magnet to be placed so that it may attract from their course a stream of iron particles, and let this stream pass at such a distance that part of it may not be affected at all ; those particles which are attracted may be conceived to strike on a white body placed beyond the magnet, and to make a mark there of a size proportional to their number. Let now another equal stream considerably adulterated by carbonaceous matter, oxygene, &c. pass by at the same distance, and in the same direction. Part of this will also be attracted, but not so far from its course, nor will an equal number be affected at all ; so that the mark made on the white body will be nearer the direction of the stream, and of less size than that made by the pure iron. It matters not whether all this would actually happen, even allowing we could place the subjects in the situation described; the thing may easily be conceived, and affords a good enough illustration of what happens in the case of light. Pursuant to the plan I before followed, I now tried to measure the different de- grees of reflexity, &c. of the different rays ; but though the measurements taken agreed in this, that the red images were much larger than the rest, and the green appeared by them of a middle size, yet they did not agree well enough (from the roughness of the images, and several other causes of error), to authorize us to con- clude with any certainty " that the action of bodies on the rays is in proportion to the relative sizes of these rays." This however will most probably be afterwards found to be the case ; in the mean time there is little doubt that the sizes are the cause of the fact. II. Several phenomena are easily explicable on the principles just now laid down. I. If a pin, hair, thread, &c. be held in the rays of the sun refracted through a prism, extending through all the 7 colours, a very singular deception takes place : the body appears of different sizes, being largest in the red and decreasing gradually to- wards the violet. This appearance seemed so extraordinary, that some friends who happened to see it as well as myself, suspected the body must be irregular in its shape. On inverting it however, the same thing took place ; and on turning the prism on its axis, so that the different rays successively fell on the same parts, the visible magnitude of the body varied with the rays that illuminated it. The appear, ance is readily accounted for by the different reflexity of the rays, and follows im- mediately from obs. 2 and 3. 2. Sir Isaac Newton found that the rings of colours made by thin plates and by thick plates of glass, as he calls them, when formed of homogeneal light, varied in size with the rays that made them, being largest in the most flexible rays. I have VOL. XVIII, D D 202 PHILOSOPHICAL TRANSACTIONS. [ANNO 17Q7- had the pleasure of observing several other sorts of rings, so extremely similar, and formed by flexion, that I can no longer doubt of this being also the cause of the phenomena observed by Newton. I shall first describe a species, to prove " that the colours by thick and thin plates are one and the same phenomenon, only differ- ing in the thickness of the plates." Happening to look by candle-light on a round concave plate of brass, pretty well polished, so as to reflect light enough for show- ing an image of the candle, I was surprized to see that image surrounded by several waves of colours, red, green, and blue, disposed in pretty regular order. This was so uncommon in a metallic speculum, that I examined the thing very minutely by a variety of experiments ; these I shall not particularly now describe, but give a general idea of their results. It must be observed, for the sake of clearness, that in the following inquiries concerning the formation of rings or fringes, the diameter of a ring or fringe means the line passing through the centre of that ring, and terminated at both ends by the circumference; whereas the breadth means that part of the diameter intercepted between the limits of the ring, or the distance between its extreme colours, red and violet. In the 1st place, they were formed by the sun's light in the figure of rings surrounding the centre of the sphere to which the plate was ground, at greater dis- tances increasing their breadths, the colours pretty bright, though inferior in bril- liancy to those of concave specula. 2dly, The order of the colours was in all red outermost, and violet or blue innermost, with a greyish-blue spot in the common centre of the whole; and on moving the plate from the perpendicular position, the rings moved and broke exactly like those of specula. In the 3d place, homogeneal light made them of simple colours ; they were broadest when red, narrowest when blue and violet. 4thly, They decreased in breadth from the centre ; and I found, by a simple contrivance, that they were to each other in the very same ratio that the rays by specula follow. In the 5 th place, I compared the general appearance of the 2 sorts by viewing them at the same time, and was struck with their general appearance, unless that these of specula were most vivid and distinct. • These things made me suspect that they were actually caused by the thin coat of gums with which the surface of the plate was varnished, called lacker. Accordingly I took it off with spirit of wine, and found the rings disappear ; on lackering it again they returned ; and in like manner I caused a well finished concave metal speculum to form the rings here spoken of, by giving it a thin coat of lacker. This is a clear proof that these rings were exactly the same with those of thick plates, to use Newton's expression, for the coat of gums is, when thin, pretty transparent, as may be seen by laying one on glass plates. But this coat is extremely thin, and cannot exceed the 200th part of an inch ; so that the colours of thick plates are in fact the very same with those of thin plates, except that the 2 kinds are made by different sized plates. We cannot therefore distinguish them, any more than we do the spectrum made by a prism whose angle is go0 from that made by one whose angle is 20°. This kind of colours is not the only one I have observed of nearly the VOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. 203 same kind with those of plates ; we shall presently see another much more curious and remarkahle. III. In reflecting on the observations and conclusions contained in my former paper, several consequences seemed to follow, which appeared so new and uncommon, that I began to doubt a little the truth of the premises ; but at any rate was re- solved to examine more minutely how far these inferences might be consistent with fact : and I am happy in being able to announce the completeness of that con- sistency, even beyond my expectations. The chief consequences were the follow- ing, l. That a speculum should produce, by flexion and reflexion, colours in its reflected light wherever it has the least scratch or imperfection on its surface. 2. That on great inclinations to the incident rays all specula, however pure and highly polished, should produce colours by flexion. 3. That they should also in the same case produce colours by reflexion. 4. That lenses, having the smallest imperfections, should produce by flexion colours in their refracted light. 5. That there should be many more than 3, or even 4 fringes by flexion, invisible to the naked eye. And, 6\ That Iceland crystal should have some peculiarities with re- spect to flexion and reflexion ; or if not, that some information should be acquired concerning its singular properties respecting refraction. The manner in which the first of these propositions is demonstrated a priori, is evident from fig. S, where cd is the reflecting surface, vo a concavity bearing a small ratio to cd, ao and ab rays proceeding to cd. The one, ab, will be sepa- rated into Br red, and bv violet, by deflexion from o, and will be reflected to rV, forming there the fringes. The other, ao, being reflected, will be separated into bx and By, by deflexion from v, forming other fringes, xy, on the side of vo's shadow opposite to rV. Also when vo is convex, instead of concave, the like fringes will be produced by the rays being deflected in passing by its sides. Lastly, when vo is a polished streak, images by reflexion will be produced, as described in my former paper for 179^* The same passage will also show the reason why, on great inclinations, colours by reflexion should be produced. And the 2d propo- sition, with respect to flexion, follows from what has been demonstrated in this paper, it being that case where the rays either leave or fall on the speculum at such an inclination, as to come only within the sphere of inflexion, without being de- flected. The 4th proposition is merely a simple case of flexion. And the last 2 require no illustration. I shall now relate how I inquired into the truth of these things a posteriori. Observ. 1. Looking at a plane glass mirror exposed to the sun's light, I observed that up and down its surface there were minute scratches, called hairs by workmen, and that each of these reflected a bright colour, some red, others green, and others blue. On moving the mirror to a different inclination, or my eye to a different position with respect to the mirror, I saw the species of the colours change; the red, for instance, became green, and the green blue. I applied my eye close to the mirror, and received on it the light reflected from one hair. I observed several dis- D D 2 204 PHILOSOPHICAL TRANSACTIONS. [ANNO 1707. tinct images of the sun much distended and regularly coloured, just like those described above; the same appearances were observable in all specula, metal and glass, which had these hairs, and I never saw any metal one without some: their size is exceedingly small, not above l75Vo- of an inch. Rubbing a minute particle of grease on the surface of the speculum, images were seen on the fibrous surface; and they always lay at right angles to that direction in which the grease was disposed by drawing the hand along it. Observ. 2. Besides these polished hairs, many specula have fewer or more smaH specks and threads, rough and black. Perhaps every polished surface is studded with a number of small ones, invisible to the naked eye from the quantity of regu- lar light which it reflects. I took, from a reflecting telescope, a small concave speculum not very well finished; its surface showed several specks to the naked eye, and many with a microscope. Its diameter was -§-* of an inch, its focal distance 2 inches, and the sphere to which it was ground 8 inches diameter. I placed it at right angles to the sun's rays, coming through a small hole -^ of an inch diameter, into a very well darkened room; I then moved it vertically, so that the .rays might be reflected to a chart 12 inches from the speculum, and consequently 10 from the focus: and though the focus appeared white and bright, yet on the chart the broad image was very different. It was mottled with a vast number of dark spots: these were of 2 sorts chiefly, circular and oblong. Of the former a considerable number were distinct and large, the rest smaller and more confused, but so numerous that they seemed to fill the whole image. None were quite black, but rather of a bluish grey, and the oblong ones had a line of faint light in the middle, just as is the case in shadows of small bodies. But the chief thing I remarked was the colours. Each oblong and round spot was bordered by a gleam of white, and several coloured fringes separated by small dark spaces. The fringes were exactly like those surround- ing the shadows of bodies, of the same shape with the dark space, having the colours in the order, red on the outside, blue or violet in the. inside; the inner- most fringe was broadest, the others decreasing in order from the firsts I could sometimes see 4 of them, and when made at the edge of the large image, I could indistinctly discern the lineaments of a 5th: when 2 of the spots were very near each other, their rings or fringes ran into each other, crossing. Observ. 3. When the chart was removed to a greater distance, as 6* feet, the fringes were very distinct and large in proportion ; also the smaller spots became more plain, and their rings were seen, though confusedly, from mixing with each other. When the speculum was turned round horizontally, so that its inclination to the incident rays might be greater, the distance of the chart remaining the same, by being drawn round in a circle, the spots and fringes evidently were distended in breadth. I have endeavoured to exhibit the sun's image, as mottled with fringes or rings and spots, in fig 9. Observ. 4. I placed the speculum behind a screen with a hole in it, through which were let pass the homogeneal rays of the sun, separated by refraction through VOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. 205 a prism ; this being turned on its axis, the rays which fell on the speculum were changed ; the fringes were now of that colour whose rays fell, and when the rays shifted, the fringes contracted or dilated, being broadest in the most flexible rays, and consequently in those whose flexity is greatest. Observ. 5. The direct light falling on the speculum, and part of the reflected light on the horizontal white stage of a very accurate micrometer, I measured the breadth of the fringes, spots, &c. These, with the distance of the speculum from the window and micrometer, and the size of the sun's image, are set down in the following table, all reduced to inches and decimals. Inches. Parts. Distance of the speculum from the hole in the Breadth of the oblong dark spot 0074 window shutter 24 Breadth of its first fringe 0022 Distance of the speculum from the stage of the Elliptic spot's transverse axis 01 16 micrometer 18 conjugate axis 0068 Transverse axis of the sun's image 2.6 Breadth of its first fringe 0034 Conjugate axis of the sun's image 1.4 Transverse axis of a larger elliptic spot . . . .013 Length of the oblong dark spot 4 Conjugate axis of the same spot 0076" In the image where these measures were taken, there were 7 other elliptic spots, a little less and nearly equal; all the others were much smaller and more confused. Observ. 6. On viewing the surface of the speculum attentively in that place whence the rays formed the oblong and first mentioned elliptic spots, I saw a dark but very thin long scratch, and a dark dent, similar in shape to the dark spaces on the image; the dark spot measured less than -,-i-g- of an inch; which makes its whole surface to the whole polished surface as 1 to 34225, supposing the former circular or nearly so. All these measures will be found to agree very well, for their smallness and delicacy : thus, the ratio last mentioned is nearly the same which we obtain by comparing the image and the spot ; the like may be said of the two spots mentioned in the table, i. e. their axes are proportional. I now could produce what spots I pleased, by gently scratching the speculum, or by making lines, dots, &c. with ink, and allowing it to dry ; for these last formed convex fibres, which pro- duced coloured fringes as well as the concavities, agreeably to what was deduced a priori. Observ. 7. The whole appearance which I have been describing bore such a close and complete resemblance to the fringes made round the shadows of bodies, that the identity of the cause in both cases could not be doubted. In order however to show it still further, I measured the breadths of 2 contiguous fringes in several different sets; the measurements agreed very well, and gave the breadth of the first fringe .005(3, and of the 2d .0034; or of the first .0066, and of the 2d .0034. The ratio of the breadths by the first is 28 to 17; by the 2d 30 to 17; of which the medium is 29 to 17, and this is precisely the ratio of the 2 innermost fringes made by a hair, according to Sir Isaac Newton's measurement: the first being, according to him, ^fy °f an mcn5 tne 2c* yH °f an inch*. Further, the 2 in- * Optics, Book 3. Obs. 3.— Orig. 206 PHILOSOPHICAL TRANSACTIONS. [ANNO 1797. nermost rings made by plates have their diameters (not breadths) in the ratio of 1-14- to 2-§-*, and the distance between the middle of the innermost fringes, made by a hair, on either side the shadow, is to the same distance in the 2d fringes, as ^i_ to ^-; therefore the diameters of the first 2 rings made by the specks in the speculum, are as -§-§-§- to -rinrri which ratio differs exceedingly little from that of 1-ff to 2f, the ratio of the diameters of rings made by plates, either those called by Newton thick, or those which he names thin: for suppose this difference nothing, 2-f- X -H4 = ]t4- X -rVsV; and tne difference between these 2 products, now stated equal, is not much above -§- in reality. Observ. 8. The last thing worth mentioning in these phenomena was this: I viewed the fringes through a prism, holding the refracting angle upwards, and the axes parallel to that of the dark space; then moving it till the objects ceased descending, I saw in that posture the fringes much more distinct and numerous; for I could now see 5 with ease, and several more less distinctly. This led me to try more minutely the truth of the 5th proposition, with respect to the number of the fringes surrounding the shadows of bodies in direct light. Having produced a bright set of these by a blackened pin -^ of an inch in diameter, I viewed them through a well made prism, whose refracting angle was only 30°, and held this angle upwards, when the fringes were on the side of the shadow opposite to me; 1 then moved the prism round on its axis, and when it was in the posture between the ascent and descent of the objects, I was much pleased to see 5 fringes plainly, and a great number beyond, decreasing in size and brightness till they became too small and confused for sight. In like manner those formed by a double flexion of 2 bodies, and those made out of homogeneal light, were seen to a much greater number when carefully viewed through the prism. And this experiment I also tried with all the species of fringes by flexion which I could think of. Observ. Q. The same appearances which were occasioned by the metal speculum, might be naturally expected to appear when a glass one was used. But I also found the like rings or fringes of colours and spots in the image beyond the focus of a lens; nor was a very excellent one belonging to a Dollond's telescope free from them. The rings with their dark intervals resembled those floating specks so often ob- served on the surface of the eye, and called " muscae volitantes," only that the muscae are transparent in the middle, because formed hydrops of humor: they will however be found to be compassed by rings of faint colours, which will become exceedingly vivid if the eyes be shut and slowly opened in the sun's light, so that the humour may be collected; they also appear by reflexion, mixed with the colours described in Phil. Trans, for 1796. Observ. 10. The sun shining strongly on the concave metal speculum, placed at such a distance from the hole in the window that it was wholly covered with the light; on inclining it a little, the image on the chart was bordered on the inside with 3 fringes similar to those already described; on increasing the inclination these * Book 2. Parts 1 and 4. — Orig. VOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. 207 were distended, becoming very bright and beautiful; when the inclination was great, and when it was still increased, another set of colours emerged from the side next the speculum, and was concave to that side. Here I stopped the motion, and the image on both sides of the focus had 3 sets of fringes, and 4 fringes in each set; but when viewed through a prism, as before described, the numbers greatly in- creased, both the fringes and the dark intervals decreasing regularly. The ap- pearance to the naked eye is represented in fig. 10, where adc being the image, A and c are the sets of fringes at the edges, and b the 3d set, there being none at e and d the sides, since the light which illuminates these quarters comes not from the edges of the speculum in so great inclinations. I now viewed the surface of the speculum, and saw it, in the place answering to b in the image, covered with fringes exactly corresponding with those at b ; and on changing the figure of that part of the speculum's edge between them and the sun, the fringes likewise had their figure altered in the very same way. On moving the speculum farther round, b came nearer to a in the image, according as the fringes on the speculum receded from that side which formed them; and before they vanished alike from the speculum and image, they mixed with the colours at a in the image, and formed in their motion a variety of new and beautiful compound colours: among these I particu- larly remarked a brown chocolate colour, and various other shades and tinges of brown and purple. Just before the fringes at b appeared, the space between a and c was filled with colours by reflexion, totally different in appearance from the fringes; but I could not examine them so minutely as I wished in this broad image, I therefore made the following experiment. Observ. 11. At the hole in the window-shutter I held the speculum, and moved it to such an inclination that the colours by reflexion might be formed in the image; they were much brighter and far more distended than the fringes, and were in every respect like the images by reflexion in the common way, only that the colours were a little better and more regular. They were also seen on the speculum as the 3d set of fringes had before been in observ. 10; but by letting the rays fall on the half next the chart, and inclining that half very much, I could produce them, though less distinctly, by a single reflexion. I now held a plain metal speculum so, that the rays might be reflected to form a white image on a chart: On inclining the speculum much, I saw the image turn red at the edge; it then became a little distended; and lastly, fringes emerged from it well coloured, and in regular order*, with their dark intervals. This may easily be tried by candle-light with a piece of looking-glass, and those who without much trouble would satisfy themselves of the truth of the whole experiment contained in this and the last observation, may easily do it in this way with a concave speculum ; but the beauty of the appearance is hereby quite impaired. After this detail it is almost superfluous to add, that the fringes at b, fig. 6, are formed by deflexion from the edge of the speculum next the sun, and then falling on it are reflected to the chart; that the images by re- flexion are either formed by the light being decompounded at its first reflexion, 208 • PHILOSOPHICAL TRANSACTIONS. [ANNO 1797. and then undergoing a second, or, in other instances, without this second re- flexion; and that the other fringes are produced exactly as described above, from the necessary consequences of the theory. I shall only add, that nothing could have been more pleasing to me than the success of this experiment; not only be- cause in itself it was really beautiful from its variety, but also because it was the most peremptory confirmation of what followed from the theory a priori, and in that point where the singularity of its consequences most inclined me to doubt its truth. Let us now attend to several conclusions to which the foregoing observations lead, independently of the propositions, viz. the first 5, which they were made to examine. 1. We must be immediately struck with the extreme resemblance between the rings surrounding the black spots on the image made by an ill polished speculum, and those produced by thin plates observed by Newton ; but perhaps the resem- blance is still more conspicuous in the colours surrounding the image made by any speculum whatever, and fully described in observ. 10 and 11. The only difference in the circumstances is now to be reconciled. The rings surrounding the black spot on the top of a bubble of water, and those also surrounding the spot between 2 object glasses *, have dark intervals, exactly like those rings I have just now described, and the fringes surrounding the shadows of bodies; but these intervals transmit other fringes of the same nature, though with colours in the reverse order; from which Sir Isaac Newton justly inferred, that at one thickness of a plate the rays were transmitted in rings, and at another reflected in like rings. Now it is evident, that neither reflexibility nor refrangibility will account for either sort of rings, because the plate is far too thin for separating the rays by the latter, and because the colours are in the wrong order for the former; and also because the whole ap- pearance is totally unlike any that refrangibility and reflexibility ever produce. To say that they are formed by the thickness of the plates, is not explaining the thing at all. It is demanded in what way ? and indeed we see the like dark intervals and the same fringes formed at a distance from bodies by flexion, where there is no plate through which the rays pass. The state of the case then seems to be this: " when a phenomenon is produced in a particular combination of circumstances, and the same phenomenon is also produced in another combination, where some of the circumstances, before present, are wanting; we are intitled to conclude that the latter is the most general case, and must try to resolve the other into it." In the first place, the order of the colours in the Newtonian rings is just such as flexion would produce; that is, those which are transmitted have the red inner- most, those which are reflected have the red outermost ; the former are the colours arranged as they would be by inflexion, the latter as they would be by deflexion ; and here by outermost and innermost must be understood relative position only, or position with respect to the thickness of the plate, not of the central spot. 2dly, * Optics, Book 11. P. l.—Orig. VOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. 20Q the thinnest plate makes the broadest ring, the diameter of the rings being in the inverse subduplicate ratio of the plate's thickness; just so is it with fringes by flexion; nearer the body the fringes are broadest, and their diameters increase in the same ratio with the diameters of the rings by plates whose thickness is uniform; each distance from the bending body therefore corresponds with a ring or fringe of a particular breadth, and the alternate distances correspond with the dark intervals: the question then is, what becomes of the light which falls on or passes at these al- ternate distances? In the case of thin plates, this light is transmitted in other rings; we should therefore be led to think that in the case of the light passing by bodies, it should be at one distance inflected, and at another deflected; and in fact the phenomena agree with this, for fringes are formed by inflexion within the shadows of bodies; they are separated by dark intervals; the fringes and the intervals with- out the shadow decrease in breadth according to the same law; so that the fringes and intervals within the shadow correspond with the intervals and fringes without, respectively. Nor will this explanation at all affect the theory formerly laid down ; it will only, if found consistent with further induction, change the definite spheres of inflexion and deflexion into alternate spheres. At any rate, the facts here being the same with those described by Newton, but in different circumstances, teach us to reconcile the difference, which we have attempted to do, as far as is consistent with strictness; and what we have seen not only entitles us to conclude that the cause is the same, but also inclines us to look for further light concerning that cause's general operation: and I trust some experiments which I have planned, with an instrument contrived for the purpose of investigating the ratio of the bending power to the distances at which it acts, will finally settle this point. II. Another conclusion follows from the experiments now related, viz. that we see the great importance of having specula for reflectors delicately polished ; not only because the more dark imperfections there are on the surface, the more light is lost, and the more colours are produced by flexion (these colours would be mostly mixed and form white in the focus), but also because the smallest scratches or hairs, being polished, produce colours by reflexion, and these, diverging irregularly from the point of incidence, are never collected into a focus, but tend to confuse the image. Indeed it is wonderful that reflectors do not suffer more from this cause, considering the almost impossibility of avoiding the hairs we speak of: however, that they do actually suffer is proved by experience. I have tried several specula from reflecting telescopes, and found that though they performed very well, from having a good figure, yet from the focus, when they were held in the sun's light, several streaks diverged, and were never corrected ; others had the hairs so small, that it was very difficult to perceive the colours produced by them, unless they fell on the eye. Glass concaves were freer from these hairs, but they were much more hurt by dark spots, &c. In general, the hairs are so small in well wrought metals, that they do little hurt ; but when enlarged by any length of ex- posure to the light and heat in solar observations, they produce irregularities round vol. xvm. E E 210 PHILOSOPHICAL TRANSACTIONS. [ANNO J 797- the image. Such at least I take to be the explanation of the phenomenon, observed at Paris by M. de Barros during the transit of Mercury in 1743, and recorded in Phil. Trans, for 1753. But there is another more serious impediment to the per- formance of reflectors, and which it is to be feared we have no means of removing. In making the experiments of which the history has been given, on viewing atten- tively the surface of the speculum, every part of it was seen covered with points of colours, formed by reflexion from the small particles of the body. I never saw a speculum free in the least from these, so that the image formed in the focus must be rendered much more dim and confused by them, than it otherwise would be. III. The last conclusion which may be drawn from these experiments, is a very clear demonstration in confirmation of what was otherwise shown, concerning the difference between coloured images produced by reflexion, and those made by flexion. This complete diversity is most evident in the experiments with specula, the colours produced by which, in the form of fringes and rings, ought, as well as the others described as images by reflexion in obs. 11, to be the same in appear- ance with those formed by pins ; whereas no 2 things can be more dissimilar. It remains to examine the 6th proposition : for this purpose I made the following observations. Observ. 1. Having procured a good specimen of Iceland crystal, I split it into several pieces, and chose one whose surface was best polished. I exposed this to a small cone of the sun's light, and received the reflected rays on a chart : nothing was observable in the image, more than what happens in reflexion from any other polished body. Some pieces indeed doubled and tripled the image, but only such as were rough on the surface, and consequently presented several surfaces to the rays : when smooth and well polished, a single image was all that they formed. The same happened when I viewed a candle, the letters of a book, &c. by reflexion from the Iceland crystal. Observ. 2. I ground a small piece of Iceland crystal round at the edge, and gave it a tolerable polish here and there by rubbing it on looking-glass, and sometimes by a burnisher (it would have been next to impossible to polish it completely). I then placed the polished part in the rays near the hole in the window-shutter, and saw the chart illuminated with a great variety of colours by reflexion, irregularly scattered, as described above * ; I therefore held the edge in the smoke of a candle and blackened it all over, then rubbed off a very little of the soot, and exposed it again in the rays. I now got a pretty good streak of images by reflexion, in no respect differing from those made in the common way. Nor could I ever produce a double set, or a single set of double images, by any specimen properly prepared, either on a chart by the rays of the sun, or on my eye by those of a candle. Observ. 3. I ground to an even and pretty sharp edge 2 pieces of Iceland crystal, and placed one in the sun's rays. At some feet distance I viewed the fringes with which its shadow was surrounded, and saw the usual number in the usual order. • Phil. Trans, for 1796.— Orig. VOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. 211 I then applied the other edge so near that their spheres of flexion might interfere in the manner before described *, and thus the fringes might be distended : still no uncommon appearance took place ; nor when other bodies were used with one i0. „r ^-jrofal nor when polished pieces of different shapes and sizes were em- ployed. The same things happened uy uuu.,-,>&«.., _.. ^ . , , w _* .. ..., Urktnnm^ neal light. In short, I repeated most of my experiments on flexion with Iceland crystal, and found that they were not changed at all in their results. Observ. 4 . Having great reason to doubt the accuracy of an experiment tried by Mr. Martin, and in which, by a prism of Iceland crystal, he thought 6 spectra were produced, I was not much surprized to find, that a prism made by polishing the 2 contiguous sides of a parallelopiped of Iceland crystal produced only 2 equal and parallel images, in whatever position the prism was held. But though, from the imperfect account which Martin gives of this appearance, it was impossible to discover his error from his own words, yet chance led me to find out what most probably had misled him ; for looking at a candle through the opposite sides of a specimen of Iceland crystal, I saw 4 coloured images, besides 2 white ones, of the candle. These were parallel to one another, and in the same line, as represented in fig. 11, where e represents the two regular images, g and p two others coloured very irregularly, and changing colours as the crystal was moved horizontally, some- times appearing each two-fold, and its 2 parts of the same or different colours. A and b were regularly coloured, and evidently formed by refraction, and reflected back from the sides. On turning the crystal round, so that its position might be at right angles to its former position, the images moved round, and were in a line perpendicular to ab, as cd. All this happened in like manner in the sun's rays ; and on viewing the specimen, I found it was split and broken in the inside, so as to be lamellated in directions parallel, or nearly so, to the sides ; on these plates there were colours in the day-time by the light of the clouds : and it is evident that it was these fractures which caused the irregular images g and p, for other speci- mens showed no such appearance. I would therefore conclude, that Iceland crys- tal separates the rays of light into 2 equal and similar beams by refraction, and no more *j~. As to the cause of the separation, I would hope that some information may be obtained from the experiments I have related : for from them it appears, that this singular property extends no farther than to the action of the particles of Iceland * Phil. Trans, for 1796, page 256. — Orig. + Mentioning this account of Martin's mistake to Professor Robison, of this university, I was pleased to find a full confirmation of it. It was that excellent philosopher who showed die appearance to Mar- tin j but he not understanding it, took the liberty of publishing the observation as his own, after first mangling it in such a way as to give him indeed some pretext for the appropriation. The Professor merely mentioned his having communicated it to Mr. Martin ; how the latter used it we have shown in the text : the theory of the appearance is somewhat more complex than appears by my observations. I was therefore pleased to find that the Professor was in possession of the true account of it ; which is however foreign to the present purpose. — Orig. £ £ 2 212 PHILOSOPHICAL TRANSACTIONS. [ANNO 1707- crystal on the particles of light in their passage through the body ; and from obs. 4 it is further evident, that it is not owing to the different properties which Sir Isaac Newton conjectures the different sides of rays to have ; for if this were the cau^e, when the rays pass between 2 pieces of crystal or. "- *...».*. ■•~ui" mmmma ^mci Mmmafi anoiner tact, mis-stated by Bartolin * and Rome de Lisle -j~, shows, that the unusual refraction takes place within the body, while the other, like all refractions, begins at some small distance before the rays enter. The writers just now quoted assert, that if the crystal be turned round so as to assume different positions, there is one in which the line appears single. The fact is very difFerent, as follows. When the crystal is turned round, the unusual image moves round also, and appears above the other ; the greatest distance between the 2 images is when they are parallel to the line bisecting one of the acute angles of the parallelogram through which the rays pass ; when the images are parallel to a line bisecting one of the obtuse angles, they seem to coincide; but they will be found, if observed more nearly, to coincide only in part. Thus, in fig. 13, ab and cd are the 2 black lines at their greater distance, and their extremities a and c, b and d are even with each other ; that is, the figure formed by joining a and c, b and d, is a rectangle. But in the other case, fig. 12, ab and cd being the lines, the space cb, equal in depth of colour to the real line on the paper, is the only place in which the lines or images coincide. The space ac of ab, and bd of cd are still of a light colour, and the 2 lines ab and cd do not coincide, by the difference ac or bd ; that is, by the difference op, the greatest distance; fig. 13. In short, the unusual line's extremities describe circles, in the motion of the crys- tal, whose centres are the extremities of the usual line, and whose radii are the greatest distance. From this it appears evident, that the unusual image is formed within the crystal, and turns round with the side of the particle, or rhomboidal mass of particles, which forms it. Further, it is evident that the power which produces the division of the incident light, is very different from common refrac- tion, from the motion, and the effect taking place when the rays are perpendicular. Suspecting therefore, that it might be owing to flexion, I made the following expe- riment, which undeceived me. Observ. 5. I covered one side of a specimen of Iceland crystal, 3 inches deep, with black paper, all but a small space TV of an mcn m diameter, and placed a screen with a hole of the same size, 6* feet from the hole in the window-shutter of my darkened chamber, so that the rays might pass through the screen, and fall on a prism placed behind, to refract them into a small and well defined spectrum, which was received on a chart 2 feet from the prism. This spectrum I viewed through the crystal, and of course saw it doubled ; but the 2 images were by no means parallel ; the unusual one inclined to the red, and its violet was considerably farther removed from the violet of the other, than the 2 reds were from each other : which shows that the most refrangible or least flexible rays were farthest • Experiment Cryitalli. — Orig. ^ Cristallographie, vol. i. — Orig, TOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. 213 moved from their course by the unusual action, and proves this to be very different from flexion *. From ail these observations this conclusion follows : that the remarkable pheno- menon in question arises from an action very different from either refraction or flexion ; and whose nature well deserves to be further considered. It may possibly belong to the particles of Iceland crystal, and in a degree to those of rock crystal, from the form and angles of the rhomboidal masses, of which these bodies are composed. Nor is this conjecture at all disproved by the fact, that glass shaped like these bodies wants the property ; for we cannot mould the particles of glass, we can only shape large masses of these ; whereas we cannot doubt that in crystal- lization the smallest masses assume the same form with the largest : but then other hypotheses may perhaps also account for the fact, such as atmospheres, electric fluid, &c. &c. ; so that till further observations are made, we ought to rest content- ed with barely suggesting the query. In the mean time, reserving to a future op- portunity some inquiries concerning the chemical properties of light, and the nature of the forces which bodies exert on it internally, I conclude at present with a short summary of propositions. But first, may I be permitted to express a hope, that what has been already attempted may prove acceptable to such as love to admire the beautiful regularity of nature, or more particularly to trace her operations, as exhibited in one of the most pleasing, most important, and most unerring walks of physical science. Prop. 1. The sun's light consists of parts which differ in degree of refrangity, reflexity, Inflexity, and deflexity ; and the rays which are most flexible have also the greatest refrangity, reflexity, and flexity ; or are most refrangile, reflexile, and flexile. — Prop. 2. Rays of compound light passing through the spheres of flexion and falling on the bending body, are not separated by their flexibility, either in their approach to, or return from the body. — Prop. 3. The colours of thin and those of thick plates are pre- cisely of the same nature ; differing only in the thickness of the plate which forms them. — Prop. 4. The colours of plates are caused by flexion, and may be produced without any transmission whatever. — Prop. 5. All the consequences deducible from the theory a priori are found to follow in fact. — Prop. 6. The common fringes by flexion, called hitherto the " 3 fringes," are found to be as numerous as the others. — Prop. 7. The unusual image by Iceland crystal is caused by some power inherent in its particles, different from refraction, reflexion, and flexion. — Prop. 8. This power resembles refraction in its degree of action on different rays ; but it resembles flexion within the body, in not taking place at a distance from it j in acting as well on perpendicular as on oblique rays ; and in its sphere or space of exertion moving with the particles which it attends. XVI I. On Gouty and Urinary Concretions. By IV. Hyde IVollaston, M. D., F. R. S. p. 386. ' If in any case a chemical knowledge of the effects of diseases will assist us in the cure of them, in none does it seem more likely to be of service than in the removal of the several concretions that are formed in various parts of the body. Of these, one species from the bladder has been thoroughly examined by Scheele^ who found it to consist almost entirely of a peculiar concrete acid, which, since his * When a candle or line is viewed through a deep specimen, the unusual image is tinged with colours. — Orig. 214 PHILOSOPHICAL TRANSACTIONS. ["ANNO 1797. time, has received the name of lithic acid. In the following paper I purpose giving an account of the analysis of gouty concretions, and of 4 new urinary calculi. The gouty matter, from its appearance, was originally considered as clmik , but from being found in an animal not known to contain or secrete calcareous earth uncombined with phosphoric acid, it has since been supposed to resemble earth of bones. Dr. Cullen has even asserted, that it is f very entirely' soluble in acids. The assertion however, is by no means generally true, and I think he must pro- bably have used the nitrous acid, for I find no other that will dissolve it. Another opinion, and I believe at this time the most prevalent, is, that it consists of lithic acid, or matter of the calculus described by Scheele. But this idea is not I believe founded on any direct experiments, nor is it, to my knowledge, more ably sup- ported than by Mr. Forbes, who defends it solely by pathological arguments from the history of the disease. Had he undertaken an examination of the substance itself, he would have found that, instead of a mere concrete acid, the gouty matter is a neutral compound, consisting of lithic acid and mineral alkali ; as the following experiments will prove. (1) If a small quantity of diluted vitriolic acid be poured on the chalk-stone, part of the alkali is extracted, and crystals of Glauber's salt may be obtained from the solution. Common salt may still more easily be procured by marine acid. The addition of more acid will extract the whole of the alkali, leaving a large propor- tion of the chalk-stone undissolved ; which exhibits the following characteristic properties of lithic matter, (a) By distillation it yields a little volatile alkali, Prus- sic acid, and an acid sublimate, having the same crystalline form as the sublimate observed by Scheele. (b) Dissolved in a small quantity of diluted nitrous acid it tinges the skin with a rose colour, and when evaporated leaves a rose-coloured de- liquescent residuum, (c) It dissolves readily in caustic vegetable alkali, and may be precipitated from it by any acid, and also by mild volatile alkali ; first as a jelly, and then breaking down into a white powder. (2) In distillation of the chalk-stone the lithic acid is decomposed, and yields the usual products of animal substances, viz. a fetid alkaline liquor, volatile alkali, and a heavy fetid oil, leaving a spongy coal ; which when burnt in open air fuses into a white salt, that does not deliquesce, but dissolves entirely in water, is alka- line and when saturated with nitrous acid gives rhomboidal crystals. These cha- racteristic properties prove it to be mineral alkali. (3) Caustic vegetable alkali poured on the chalk-stone, and warmed, dissolves the whole, without emitting any smell of volatile alkali. From which it appears, that the volatile alkali obtained by distillation is a product arising from a new arrange- ment of elements, not so combined in the substance itself. (4) Water aided by a boiling heat dissolves a very small proportion of the gouty concretion, and retains it when cold. The lithic acid thus dissolved in combination with the alkali, is rather more than would be dissolved alone ; so that by addition of marine acid it may be separated. While the solution continues warm no preci- VOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. 21 5 pitate is formed ; but as it cools, the lithic acid crystallizes on the sides of the ves- sel, in the same manner as the crystals called red sand do, when an acid is added to recent urine. The gouty concrete may be easily formed by uniting the ingredients of which I have found it to consist. (5) If a fragment of lithic acid be triturated with some mineral alkali and a little warm water, they unite, and after the superfluous alkali has been washed out, the remainder has every chemical property of gouty matter. The acid will not sublime from it, but is decomposed (2) by heat : the alkali may be extracted by the vitriolic or marine (l), or indeed by most acids. The compound re- quires a large quantity of water for its solution (4), and while warm the solution yields no precipitate by the addition of an acid ; but on its cooling the lithic crys- tals form, as in the preceding experiment. In each case the crystals are too small for accurate examination, but I have observed, that by mixing a few drops of caustic vegetable alkali to the solution previous to the decomposition, they may be rendered somewhat larger. At the first precipitation, the crystals from gouty mat- ter were not similar to those of lithic acid ; but by redissolving the precipitate in water with the addition of a little caustic vegetable alkali, and decomposing the solution as before, while hot, the crystals obtained were perfectly similar to those of lithic acid procured by the same means. Such then are the essential ingredients of the gouty concretion. But there might probably be discovered, by an examination of larger masses than I possess, some portion of common animal fibre or fluids intermixed ; but whatever particles of heterogeneous matter may be detected, they are in far too small proportion to invalidate the general result, that c gouty matter is lithiated soda.' The knowledge of this compound may lead to a further trial of the alkalies which have been ob- served by Dr. Cullen to be apparently efficacious in preventing the returns of this disease (First Lines, dlviii) ; and may induce us, when correcting the acidity to which gouty persons are frequently subject, to employ the fixed alkalies, which are either of them capable of dissolving gouty matter, in preference to the earths, termed absorbent, which can have no such beneficial effect. Fusible calculus. — My next subject of inquiry has been a species of calculus, that was first ascertained to differ from that of Scheele by Mr. Tennant ; who found that when urged by the heat of a blow-pipe, instead of being nearly consumed, it left a large proportion, fused into an opaque white glass, which he conjectured to be phosphorated lime united with other phosphoric salts of the urine, but never attempted a more minute analysis. Stones of this kind are always whiter than those described by Scheele, and some specimens are perfectly white. The greater part of them have an appearance of sparkling crystals, which are most discernible where 2 crusts of a laminated stone have been separated from each other. I lately had an opportunity of procuring these crystals alone, voided in the form of a white sand, and thence of determining the nature of the compound stone, in which these are cemented by other ingredients. The crystals consist of phosphoric acid, mag- 1\Q PHILOSOPHICAL TRANSACTIONS. [ANNO 17Q7. nesia, and volatile alkali : the stone contains also phosphorated lime, and generally some lithie acid. The form of the crystals is a short trilateral prism, having one angle a right angle, and the other 1 equal, terminated by a pyramid of 3 or 6 sides. (6) By heat the volatile alkali may be driven off from the crystals, and they are rendered opaque, or may be partially fused. The phosphorated magnesia may then be dissolved in nitrous acid ; and by addition of quicksilver dissolved in the same acid, a precipitate of phosphorated quicksilver is obtained, from which the quick- silver may be expelled by heat, and the acid procured separate. By addition of vitriolic acid to the remaining solution, Epsom salt is formed, and may be crystal- lized, after the requisite evaporation of the nitrous acid, and separation of any re- dundant quicksilver. — (7) These crystals require a very large quantity of water for their solution, but are readily soluble in most if not all acids ; viz. vitriolic, nitrous, marine, phosphoric, saccharine, and acetous ; and when precipitated from them re- assume the crystalline form. — (8) From the solution in marine acid, sal ammoniac may be obtained by sublimation. (9) Though the analysis is satisfactory, the synthetic proof is, if possible, still more so. After dissolving magnesia in phosphoric acid, the addition of volatile alkali immediately forms the crystalline precipitate, having the same figure and properties as the original crystals. — (10) If volatile alkali be cautiously mixed with recent urine, the same compound will be formed ; the first appearance that takes place when a sufficient quantity of alkali has been gradually added, is a precipitate of these triple crystals. These constitute the greater part of the fusible stone ; so that a previous acquaintance with their properties is necessary, in order to compre- hend justly the nature of the compound stone in which they are contained. The most direct analysis of the compound stone is effected by the successive action of distilled vinegar, marine acid, and caustic vegetable alkali. (11) Distilled vinegar acts but slowly on the calculus when entire; but when powdered, it immediately dissolves the triple crystals, which may be again precipi- tated from it as crystals by volatile alkali ; and if the solution has not been aided by heat, scarcely any of the phosphorated lime will be found blended with them. In one trial the triple crystals exceeded T%- of the quantity employed ; but it seemed unnecessary to determine the exact proportion which they bear to the other ingre- dients in any one instance, as that proportion must vary in different specimens of such an assemblage of substances not chemically combined. Marine acid, poured on the remainder, dissolves the phosphorated lime, leaving a very small residuum. This is soluble in caustic vegetable alkali entirely, and has every other property of mere lithie acid. The presence of volatile alkali in the compound stone may be shown in various ways. (12) In the distillation of this stone, there arises, first volatile alkali in great abundance, a little fetid oil, and lithie acid. There remains a large proportion charred. Water poured on the remaining coal dissolves an extremely small quantity VOL. LXXXVIJ.] PHILOSOPHICAL TRANSACTIONS. 217 of a salt, apparently common salt, but too minute for accurate examination. Dis- tilled vinegar dissolves no part of it, even when powdered. Marine acid dissolves the phosphorated lime and phosphorated magnesia, leaving nothing but a little charcoal. From this solution vitriolic acid occasions a precipitate of selenite, after which triple crystals may be formed by addition of volatile alkali. — (13) Marine acid also acts readily on a fragment of the stone, leaving only yellowish laminae of lithic acid. When the solution has been evaporated to dryness, sal ammoniac may be sublimed from it ; and the 2 phosphorated earths are found combined with more or less of marine acid, according to the degree of heat applied. If the pro- portion of the earths is wished to be ascertained, acid of sugar will separate them most effectually, by dissolving the phosphorated magnesia, and forming an inso- luble compound with the lime. (14) Caustic vegetable alkali has but little effect on the entire stone; but if heated on the stone in powder,- a strong effervescence takes place from the escape of alkaline air, and the menstruum is found to contain lithic acid precipitable by any other acid. Some phosphoric acid also, from a partial decomposition of the triple crystals, is detected by nitrated quicksilver. — (15) The triple crystals alone are scarcely fusible under the blow-pipe; phosphorated lime proves still more re- fractory; but mixtures of the 2 are extremely fusible, which explains the fusibility of the calculus. The appearance of the lithic strata, and the small proportion they bear to the other ingredients, shows that they are not an essential part, but an accidental deposit, that would be formed on any extraneous substance in the bladder, and which probably in this instance concretes during any temporary in- terval that may occur in the formation of the crystals. — I come now to what has been called Mulberry calculus. — This stone, though by no means overlooked, and though pointed out as differing from other species, has not, to my knowledge, been sub- jected to any further analysis than is given, in the 2d vol. of the Med. Trans., by Dr. Dawson, who found that his lixivium had little or no effect on it; and in the Phil. Trans, by Mr. Lane, who, among other simple and compound stones, gives an account of the comparative effects of lixivium and heat on a few specimens of mulberry calculus, (viz. N° 7, 8, 9, 10); but neither of these writers attempted to ascertain the constituent parts. Though the name has been confined to such stones as, from their irregularity, knotted, surface, and dark colour, bear a distant resemblance to that fruit, I find the species, chemically considered, to be more extensive, comprehending also some of the smoothest stones we meet with ; of which one in my possession is of a much lighter colour, so as to resemble in hue, as well as smoothness, the surface of a hemp-seed. From this circumstance it seems not improbable that the darkness of irregular stones may have arisen from blood voided in consequence of their roughness. The smooth calculus I find to consist of lime united with the acids of sugar and of phosphorus. The rougher specimens have generally some lithic acid in their interstices. vol. xviii. F F 218 PHILOSOPHICAL TRANSACTIONS. [ANNO 1797. (16) Caustic vegetable alkali acquires a slight tinge from a fragment of this kind of stone, but will not dissolve it. When powdered it is thereby purified from any quantity of lithic acid that it may contain. Phosphoric acid will then dissolve out the phosphorated lime, and the remainder, after being washed, may be decom- posedby the vitriolic acid. The affinity of this acid for a certain proportion of lime is superior even to that of acid of sugar; selenite is formed, and the acid of sugar may be crystallized, and by the form of its crystals recognized, as well as by every other property. It is easily soluble, occasions a precipitate from lime water, and from a solution of selenite, and with mineral alkali forms a salt that requires a large quantity of water for its solution. (17) When the stone has been finely powdered, marine acid will slowly dissolve all but any small quantity of lithic matter which it may contain. After the solu- tion has been evaporated to dryness, no part is then soluble in water, the marine acid being wholly expelled. When the dried mass is distilled with a greater heat, the saccharine acid is decomposed, and a sublimate formed, still acid and still crystallizable, but much less soluble in water, and which does not precipitate lime from lime water. After distillation, the remainder contains phosphorated lime, pure lime, and charcoal; and when calcined in the open air, the charcoal is con- sumed, and the whole reduced to a white powder. The 2 former may be dissolved in marine acid, which when evaporated to dryness will be retained only by the lime ; so that water will then separate the muriated lime, and the phosphorated lime may afterwards be submitted to the usual analysis. Bone- earth calculus. — Beside that of Scheele, and the 2 already noticed, there is also a 4th species of calculus, occasionally formed in the bladder, distinct in its appearance, and differing in its component parts from the rest; for it consists entirely of phosphorated lime. Its surface is generally of a pale brown, and so smooth as to appear polished; when sawed through, it is found very regularly laminated; and the laminae in general adhere so slightly to each other, as to separate with ease into concentric crusts. In a specimen with which I was favoured by Dr. Baillie, each lamina is striated in a direction perpendicular to the surface, as from an assemblage of crystallized fibres. The calculus dissolves entirely, though slowly, in marine or nitrous acid, and, consisting of the same elements as earth of bones, may undergo a similar analysis, which it cannot be necessary to particularize. By the blow-pipe it is immediately discovered to differ from other urinary calculi: it is at first slightly charred, but soon becomes perfectly white, still retaining its form, till urged with the utmost heat from a common blow-pipe, when it may at length be completely fused. But even this degree of fusibility is superior to that of bones. The difference consists in an excess of calcareous earth contained in bones, which renders them less fusible. This redundant portion of lime in bones renders them also more readily soluble in marine acid, and may, by evaporation of such a solution, be separated, as in the last experiment on mulberry calculus. The remaining phosphorated lime may be re-dissolved by a fresh addition of marine VOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. 21 (J acid; and being now freed from redundant lime, will, on evaporation of the marine acid, assume a crystalline form. As the laminated calculus contains no excess of lime, that will at once yield such crystals: their appearance will be described in the succeeding experiment. Calculus from the prostate gland. — There is still another calculus of the urinary passages, though not of the bladder itself, which deserves notice, not from the frequency of its occurrence, but from having been supposed to give rise to stone in the bladder. I mean the small stones which are occasionally found in the pros- tate gland. Those that I have seen, and which, by favour of Mr. Abernethy, I have had an opportunity of examining, were from the size of the smallest pin's head to that of pearl barley, in colour and transparency like amber, and appeared originally to have been spherical ; but from contiguity with others, some had flat- tened surfaces, so as at first sight to appear crystallized. These I find to be phos- phorated lime in the state of neutralization, tinged with the secretion of the prostate gland. (18) A small fragment being put into a drop of marine acid, on a piece of glass over a candle, was soon dissolved; and on evaporation of the acid, crystallized in needles, making angles of about 6o° and 120° with each other. Water dropped on the crystals would dissolve no part of them; but in marine acid they would re- dissolve, and might be re-crystallized. — (19) Vitriolic acid forms selenite with the calcareous earth. — (20) By aid of nitrated quicksilver, phosphoric acid is readily obtained. (21) When heated this calculus decrepitates strongly ; it next emits the usual smell of burnt animal substances, and is charred, but will not become white though partially fused. It still is soluble in marine acid, and will in that state crystallize more perfectly than before. Hence I conclude, that these stones are tinged with the liquor of the prostate gland, which in their original state (18) somewhat impedes the crystallization. This crystallization from marine acid is so delicate a test of the neutral phosphorated lime, that I have been enabled by that means to detect the formation of it, though the quantities were very minute. The particles of sand which are so generally to be felt in the pineal gland, have this for their basis; for I find that after calcination they crystallize perfectly from marine acid. I have likewise met with the same compound in a very pure state, and soft, contained in a cyst under the pleura costalis. On the contrary, ossifications, properly so called, of arteries and of the valves of the heart, are similar to earth of bones, in containing the redundant calcareous earth ; and I believe also those of veins, of the bronchiae, and of the tendinous portion of the diaphragm, have the same excess; but my experiments on these were made too long since for me to speak with certainty. To these I may also add the incrustation frequently formed on the teeth, which, in the only 2 specimens that I have examined, proved to be a similar compound, with a very small excess of lime. p p 2 220 PHILOSOPHICAL TRANSACTIONS. [ANNO 1797. Though I do not at present presume to draw conclusions with regard to the treatment of all the diseases in question, some inferences cannot pass unobserved. The sand from the pineal gland, from its frequency hardly to be called a disease, or when amounting to disease most certainly not known by its symptoms, would, at the same time, if known, be wholly out of the reach of any remedy. The calculi of the prostate are too rare perhaps to have been ever yet suspected in the living body, and are but indirectly worthy of notice. For if by chance one of them should be voided with the urine, a knowledge of its source would guard us against anerror we might otherwise fall into, of proposing the usual solvents for urinary calculi. The bone-earth calculus, though so nearly allied to the last, is still manifestly different, and cannot be supposed to originate from that source; but if ever the drinking of water impregnated with calcareous earth gave rise to a stone in the bladder, this would most probably be the kind generated, and the remedy must evi- dently be of an acid nature. With respect to the mulberry calculus, I fear that an intimate knowledge of its properties will leave but small prospect of relief from any solvent; but by tracing the source of the disease we may entertain some hopes of preventing it. As the saccharine acid is known to be a natural product of a species of oxalis, it seems more probable that it is contained in some other vegetables or their fruits taken as aliment, than produced by the digestive powers, or secreted by any diseased action of the kidneys. The nutriment would therefore become a sub- ject of minute inquiry, rather than any supposed defect of assimilation or secretion. When a calculus is discovered, by the evacuations, to be of the fusible kind, we seem to be allowed a more favourable prospect in our attempts to relieve: for here any acid that is carried to the bladder will act on the triple crystals, and most acids will also dissolve the phosphorated lime; while alkalies, on the contrary, would rather have a tendency to add to the disease. Though, from want of sufficient attention to the varieties of sediment from urine, and want of information with regard to the diversity of urinary calculi, the deposits peculiar to each concretion are yet unknown ; it seems probable that no long course of observation would be necessary to ascertain with what species any individual may be afflicted. The lithic, which is by far the most prevalent, fortunately affords us great va- riety of proofs of its presence. Particles of red sand, as they are called, are its crystals. Fragments also of larger masses, and small stones, are frequently passed; and it is probable that the majority of appearances in the urine called purulent, are either the acid itself precipitated too quickly to crystallize, or a neutral com- pound of that acid with one of the fixed alkalies. Beside this species, the fusible calculus has afforded decisive marks of its presence in the case which furnished me with my specimen of triple crystals; and by the description given by Mr. Forbes (in his Treatise on Gravel and Gout, ed. 1793, p. 6*5), of a white crystallized precipitate, I entertain no doubt that his patient laboured under that variety of the disease. VOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. 221 XVII 1. Experiments on Carbonated Hydrogenous Gas; with a Flew to determine whether Carbon be a Simple or a Compound Substance. By Mr. fVm. Henry, p. 401. The progress of chemical science depends not only on the acquisition of new facts, but on the accurate establishment, and just valuation, of those we already possess: for its general principles will otherwise be liable to frequent subversions; and the mutability of its doctrines will but ill accord with the unvaried order of nature. Impressed with this conviction, I have been induced to examine a late attempt to withdraw from its rank among the elementary bodies, one of the most interesting objects of chemistry. The inferences respecting the com- position of charcoal, deduced by Dr. Austin from his experiments on the heavy inflammable air, (Philos. Trans., vol. 80), lead to changes so numerous in our explanations of natural phenomena, that they ought not to be admitted without the strictest scrutiny of the reasoning of this philosopher, and an attentive repeti- tion of the experiments themselves. In the former, sources of fallacy may I think, be easily detected; and in the latter, there is reason to suspect that Dr. Austin has been misled by inattention to some collateral circumstances. Several chemists however, of distinguished rank, have expressed themselves satisfied with the evi- dence thus produced in favour of the composition of charcoal; and among these it may be sufficient to mention Dr. Eeddoes, who has availed himself of the theory of Dr. Austin, in explaining some appearances that attend the conversion of cast into malleable iron. Philos. Trans., vol. 81. The heavy inflammable air, having been proved to consist of a solution of pure charcoal in light inflammable air, is termed, in the new nomenclature, carbonated hydrogenous gas. By repeatedly passing the electric shock through a small quan- tity of this gas, confined in a bent tube over mercury, Dr. Austin found that it was permanently dilated to more than twice its original volume. An expansion so remarkable could not, as he observes, be occasioned by any other known cause than the evolution of light inflammable air. When the electrified air was fired with oxygenous gas, it was found that more oxygen was required for its saturation than before the action of the electric fluid ; which proves that, by this process an actual addition was made of combustible matter. The light inflammable air dis- engaged by the electrization, doubtless proceeded from the decomposition of some substance within the influence of the electric fluid, and not merely from the ex- pansion of that contained in the carbonated hydrogenous gas; for had the quantity of hydrogen remained unaltered, and its state of dilatation only been changed, there would not, after electrization, have been any increased consumption of oxygen. The only substances in contact with the glass tube and mercury, in these expe- riments, besides the hydrogen of the dense inflammable gas, were carbon and water; which last, though probably not a constituent of gases, is however co- 222 PHILOSOPHICAL TRANSACTIONS. [ANNO 1797. piously diffused through them. If the evolved hydrogen proceeded from the decomposition of the former of these 2 substances, it is evident that a certain volume of the carbonated hydrogenous gas must yield, after electrization, on com- bustion with oxygen, less carbonic acid than an equal volume of non-electrified gas; or, in other words, the inflammation of 20 measures of carbonated hydrogen, expanded by electricity from 10, should not afford so much carbonic acid as 10 measures of the unelectrified. From the fact which has been before stated, respecting the increased consump- tion of oxygen by the electrified air, it follows, that in determining the quantity of its carbon by combustion, such an addition of oxygen should be made, to that necessary for the saturation of the gas before exposure to the electric shock, as will completely saturate the evolved hydrogen. For if this caution be not observed, we may reasonably suspect that the product of carbonic acid is diminished, only because a part of the heavy inflammable air has escaped combustion. It might indeed be supposed, that in consequence of the superior affinity of carbon for oxygen, the whole of the former substance, contained in the dense inflammable gas, would be saturated, and changed into carbonic acid, before the attraction of hydrogen for oxygen could operate in the production of water. But I have found that the residue, after inflaming the carbonated hydrogenous gaz with a deficiency of oxygen, and removing the carbonic acid, is not simply hydrogenous, but car- bonated hydrogenous gas. In the 2d, 5th, and 6th of Dr. Austin's experiments, in which the quantity of carbon, in the electrified gas, was examined by deflagrating it with oxygen, the combustion was incomplete, because a sufficiency of oxygen was not employed; and Dr. Austin himself was aware that, in each of them, " a small quantity of heavy inflammable air might escape unaltered." It is observable also, that the product of carbonic acid, from the electrified gas, increased in proportion as the combustion was more perfect. We may infer therefore, that if it had been com- plete, there would have been no deficiency of this acid gas, and consequently no indication of a decomposition of charcoal. A strong objection however is appli- cable to these, as well as to most of Dr. Austin's experiments, that the residues were not examined with sufficient attention. In one instance we are told, that the remaining gas was inflammable, and in another, that it supported combustion like vital air. I need hardly remark, that a satisfactory analysis cannot be attained of any substance, without the most scrupulous regard, not only to the qualities, but to the precise quantities of the products of our operators. To the 8th and 9th experiments, the objection may be urged with additional weight, which has been brought against the preceding ones, that the quantity of oxygen, instead of being duly increased in the combustion of the electrified gas, was, on the contrary, diminished. Thus, in the 8th experiment, 2.83 measures of carbonated hydrogen were inflamed with 4.58 measures of oxygenous gas; but in the 9th, though the 2.83 measures were dilated to 5.1 6, and had therefore VOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. 223 received a considerable addition of combustible matter, the oxygen employed was only 4.0Q. To the rest of Dr. Austin's experiments either one or both of the above objections are applicable. The first and most important step therefore, in the repetition of these experi- ments, is to determine, whether the carbonated hydrogenous gas really sustains, by the process of electrization, a diminution of its quantity of carbon; because, should this be decided in the negative, we derive from the fact a very useful direc- tion in ascertaining the true source of the evolved hydrogen. The following ex- periments were therefore made with a view to decide this question, and the error of Dr. Austin, in employing too little oxygen, was carefully avoided.* Exper. 1 . In a bent tube, standing inverted over mercury, 94.5 measures of carbonated hydrogenous gas, from acetite of pot-ash, were mixed with 107.5 of oxygen. The total, 202, was reduced by an explosion to 128.5, and was further contracted by lime-water to 54. A solution of hepar sulphuris left only 23 mea- sures. The diminution by lime-water, viz. 74.5 measures, makes known to us the quantity of carbonic acid afforded by the combustion of 94.5 measures of car- bonated hydrogenous gas: and the residue after the action of hepar sulphuris, viz. 23 measures, gives the proportion of azotic gas contained in the carbonated hydrogen j for the oxygenous gas employed, which was procured from oxygenated muriate of pot-ash, was so pure, that the small quantity used in this experiment could not contain a measurable portion of azotic gas. Exper. 2. The same quantity of carbonated hydrogen was expanded, by repeated electrical shocks, to 188 measures. The addition of hydrogenous gas therefore amounted to 93.5. The gas thus dilated was fired, at different times, with 392.5 measures of oxygenous gas; and the residue, after these several explosions, was 203 measures. Lime water reduced it to 128.5, and sulphureof pot-ash to 19.5. In this instance, as in the former one, the product of carbonic acid is 74.5 measures. Finding, from the first experiment and other similar ones, that the carbonated hy- drogenous gas, which was the subject of them, contained a very large admixture of azotic gas, I again submitted to distillation a quantity of the acetite of pot-ash, with every precaution to prevent the adulteration of the product with atmospherical air. Such an adulteration, I have observed, impedes considerably the dilatation of the gas, and for a time even entirely prevents it. This explains the failure, which * The apparatus employed in these experiments, was the ingenious contrivance of Mr. Cavendish and is described in vol. 75, of the Philos. Trans. In dilating the gas, I sometimes used a straight tube, furnished with a conductor, in the manner of Dr. Priestley, (see his Experiments on Air, vol. 1, plate 1, fig. 16.) The bulk of the gases introduced, and their volume after the various experiments, were ascertained by a moveable scale, and by afterwards weighing the mercury which filled the tube to the marks on the scale ; by which means I was spared the trouble of graduating the syphons. Each grain of mercury indicates 1 measure of gas ; and though the smallness of the quantities submitted to experi- ment may be objected to, yet this advantage was gained, that the electrified gas could be fired at one explosion, as was done in the 4th, 6th, and 8th experiments. Errors, from variations of temperature and atmospherical pressure, were carefully avoided. — Orig. 224 PHILOSOPHICAL TRANSACTION'S. £ANNO 1797. some experienced chemists have met with, in their attempts to expand the carbo- nated hydrogenous gas by electricity. Gas which is thus vitiated, becomes how- ever capable of expansion, after exposure to the sulphure of pot-ash. Exper. 3. Carbonated hydrogen 340 measures were exploded with the proper proportion of oxygenous gas. The carbonic acid produced amounted to 380 mea- sures, and the residue of azotic gas was 20 measures. — Exper. 4. The same quan- tity, when expanded to 690, gave on combustion 380 measures of carbonic acid, and 19.8 of azotic gas. — Exper. 5. 315 measures of carbonated hydrogen yielded 359 measures of carbonic acid, and 18.5 measures of azote. — Exper. 6. The same quantity, after expansion to 000, afforded the same products of carbonic acid and azotic gases. — Exper. 7 and 8. As much carbonic acid was obtained by the com- bustion of 408 measures of carbonated hydrogenous gas, expanded from 200, as from 200 measures of the non-electric fired gas; and the residues of azotic gas were the same in both cases. It is unnecessary to state the particulars of several other experiments, similar to those above related, which were attended with the same results. They sufficiently prove that the action of the electric spark, when passed through carbonated hy- drogenous gas, is not exerted in the decomposition of carbon; for the same quantity of this substance is found after as before electrization. Even granting that char- coal is a compound, the constituents of which are held together by a very forcible affinity, it does not appear likely that the agency of the electric shock, which seems, in this instance, analogous to that of caloric, should effect its decomposition under the circumstances of these experiments. For it is a known property of char- coal to decompose water, when aided by a high temperature; and its union with oxygen is a much more probable event, when this body is present, than a separa- tion into its constituent principles. As an argument also, that water is the source of the light inflammable air in this process, it may be observed, that the dilatation in Dr. Austin's experiments could never be carried much farther than twice the original bulk of the gas*. This fact evidently implies that the expansion ceased only in consequence of the entire destruction of the matter, whose decomposition afforded the light inflammable air, and this substance could not be carbon, because Dr. Austin admits that a large portion, and I have shown that the whole of it still remains unaltered. If the dilatation of the carbonated hydrogenous gas arose from the decomposition of water, the effect should cease when this fluid is previously abstracted. To as- certain whether this consequence would really follow, I exposed a portion of the gas, for several days before electrization, to dry caustic alkali. On attempting its * " After the inflammable air has been expanded to about double its original bulk/' says Dr. Austin, '• I do not find that it increases further by continuing the shocks. Conceiving that the progress of the decomposition was impeded by the mixture of the other airs with the heavy inflammable, I passed the spark through a mixture of the heavy inflammable air and light inflammable; but the expansion suc- ceeded nearly as well as when the heavy inflammable was electrified alone." Phil. Trans, vol. 80, p. 52.— Orig. YOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. 225 expansion, I found that it could not be carried beyond £ the original bulk, of the gas. By 160 very strong explosions it attained this small degree of dilatation, but 80 more produced not the least effect; though the former number would have been amply sufficient to have dilated the gas, in its ordinary state, to more than twice its original volume. A drop or 2 of water being admitted to this portion of gas, the expansion went on as usual; and I may here observe, that when a little water gained admission into the tube along with the gas, in any experiment, which often happened before I had acquired sufficient expertness in transferring the air from water to mercury, the dilatation went on with remarkable rapidity. Carbonic acid gas, according to the discovery of M. Monge*, undergoes, when submitted to the electric shock, a change similar to that effected on the carbonated hydrogen; and the expansion has been shown, by Messrs. Landriani and Van Marum-j", to be owing to the same cause, viz. the extrication of light inflammable air. The added gas, M. Monge ably contends, cannot proceed from any other source than the water held in solution by all aeriform bodies, the oxygen of which he supposes to combine with the mercury. That the decomponent of the water however, in the experiments which I have described, is not a metallic body, will appear highly probable when we reflect that there is present in them a combustible substance, viz. charcoal, which attracts oxygen much more strongly than metals; and the following experiments evince that the mercury, by which the air was con- fined, had no share in producing the phenomena. Exper. Q. A portion of carbonated hydrogenous gas was introduced in a glass tube closed at one end, into which a piece of gold wire was inserted, that projected both within and without the cavity of the tube. The open end of the tube was then closed by a stopper perforated also with gold wire, so that electric shocks could be passed through the confined air, without the contact of any metal that has the power of decomposing water. On opening the tube with its mouth downwards, under water, a quantity of air immediately rushed out. — Exper. 10. The dilatation of the gas was found to proceed very rapidly when standing over water, and exposed to the action of the electric fluid, conveyed by gold conductors. We have only therefore, in the 2 preceding experiments, one substance into con- tact with the gas which is capable of decomposing water, viz. charcoal. The union of this body with the oxygen of the water would be rendered palpable by the for- mation of carbonic acid ; but Dr. Austin did not observe that any precipitation was occasioned in lime-water, by agitating it with the electrified gas. On passing up syrup of violets to the electrified air, with the expectation of its indicating the vola- tile alkali, as in the experiments of Dr. Austin, no change of colour took place, though the test was of unexceptionable purity. On examining however, whether any alteration of bulk had been produced in the air by the contact of this liquid, it appeared, that of 700 measures, 100 had been absorbed. Suspecting that the ab- sorption was owing to the presence of carbonic acid, I introduced some lime-water * 29 Journal de Physique, 277- — f 2 Annales de Chimie, 273. — Orig. VOL. XVIII. • G G 226 PHILOSOPHICAL TRANSACTIONS. [ANNO 1797. to a volume of the expanded gas, amounting to 556 measures, when they were immediately reduced to 512. The contraction would probably have been still more remarkable if the gas had been further expanded before the admission of the liquid. Thecha-nge in the lime-water was very trifling; but my friend Mr. Rupp, who wit- nessed this as well as several of the other experiments, and who is much conversant in the observation of chemical facts, was satisfied that, after a while, he saw small flocculi of a precipitate on the surface of the mercury. This contraction of bulk cannot be ascribed to any other cause than the absorption of carbonic acid; for besides the fact, that the colour of syrup of violets and of turmeric, which I also tried, were not affected by exposure to the electrified gas, I have this objection to the absorbed gas being ammonia, that no diminution, either of bulk or trans- parency, occurred on the admixture of muriatic acid gas with the electrified air; whereas ammonia would have been exhibited under the form of a neutral salt. When water was passed up to this mixture of the 2 gases, there was an absorption, not only of the muriatic gas, but of something more. Conceiving that the demolition of charcoal, by the action of the electric fluid, was sufficiently proved by his experiments, Dr. Austin assigns the evolved hydrogen as 1 of its constituents, and the other he concludes to be azote. This inference however rests almost entirely on estimates, in which material errors may be dis- covered. Some of these it may be well to point out, for the satisfaction of such as have acquiesced in Dr. Austin's opinion. The carbonated hydrogenous gas sub- mitted to Dr. Austin's experiments clearly appears, from his own account, to have been largely adulterated with azotic gas. One source of its impurity he has dis- closed, by informing us that the gas " had been very long exposed to water*;" for Dr. Higgins has somewhere shown that the heavy inflammable air, after standing long over water, leaves a larger residue of azote, on combustion, than when re- cently prepared -j~. It is probable also, that the proportion of azote derived from the water, would increase with the time of its exposure ; and thus a fertile source of error is suggested, which appears wholly to have escaped Dr. Austin's attention. In repeating his experiments, I was careful that comparative ones, on 2 equal quantities of the electrified and unelectrified gas, should be made, without the in- tervention of any time that could vary the proportion of azote in either of the gases. To the Qth experiment, in which the quantity of azote seems to have been in- creased by electrization, I must repeat the objection, that a sufficiency of oxygenous gas was not used in the combustion. In the 8th experiment, 2.83 of the unelec- trified air were fired with 4.17 oxygenous gas, and only 0.15 of the latter remained above what was sufficient for saturation; but in the 9th, though the 2.83 measures * 80 Phil. Trans. 54. — f Similar facts respecting the deterioration of other gases, by standing over water, may be seen in Dr. Priestley's Experiments on Air, vol. 1, p. 59, 158. I found that oxygenous gas, from oxygenated muriate of pot-ash, acquired, by exposure a few weeks to water, .125 its bulk of azotic gas. — Orig. VOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. 227 were expanded to 5.1 6, the quantity of oxygen employed was 0.08 less than in the former experiment; and it may therefore be presumed that a small quantity of in- flammable air might escape unaltered, and might add apparently to the product of azote. In the 8th experiment also, the portion of oxygenous gas that was more than sufficient to saturate the carbonated hydrogen, would probably combine, in part, with the remaining azote, as in the experiments of Dr. Higgins * and Dr. Priestley -}~. But in the 9th, the quantity of oxygenous gas was hardly sufficient to saturate both kinds of inflammable air after electrization, and could not there- fore diminish the azotic gas. When the proportion of oxygen is duly increased, and the inflammation of the electrified air is performed in small portions, there is no augmentation, but on the contrary a decrease of the quantity of the azote, as will appear on comparing the 1st and 2d of the experiments which I have related. Two circumstances were observed, in the experiments of Dr. Austin, which have not been noticed in the preceding account of the repetition of them, viz. the appearance of a deposit from the carbonated hydrogenous gas during its electriza- tion, and the formation of ammonia by the same process. In some experiments, which I made on the first portion of gas, both these facts were sufficiently apparent; but neither of them occurred on electrifying the gas which was afterwards procured. Suspecting that the cessation of them arose from the superior purity of the latter portion from azotic gas, I passed the electric shock through a mixture of carbona- ted hydrogen with about 4- its bulk of azote, and thus again produced the pre- cipitate, which would have been of a white colour, if it had not been obscured by minute globules of mercury, that were driven upwards by the force of the ex- plosion. An infusion of violets was tinged green when admitted to the electrified gas ; but the change of colour did not occur instantly, as happens from the absorp- tion of ammoniacal gas; and required for its production that the liquid should be brought extensively into contact with the inner surface of the tube. From this effect on a blue vegetable colour, we may infer that the precipitate was an alkaline substance, and probably the carbonate of ammonia; but the quantity was much too minute to be the subject of more decisive experiment. I shall conclude this memoir, with a brief summary of the facts that are esta- blished by the preceding experiments^;. Those included under the first head are de- ducible from the experiments of Dr. Austin. 1. Carbonated hydrogenous gas, in its ordinary state, is permanently dilated by the electric shock to more than twice its original volume ; and as light inflammable air is the only substance we are ac- quainted with, that is capable of occasioning so great an expansion, and of ex- hibiting the phenomena that appear on firing the electrified gas with oxygen, we may ascribe the dilatation to the production of hydrogenous gas. 2. The hydro- * Experiments and Observations on acetous Acid, &c. p. 29 j.— f 79 Phil. Trans. 7. — f Since thig paper was written I have extended the inquiry to phosphorated hydrogenous gas, which expands equally with the carbonated hydrogen 3 loses its property of inflaming when brought into contact with oxygenous gas ; and affords evident traces of a production of phosphorous or phosphoric acid. — Orig. G G 2 228 PHILOSOPHICAL TRANSACTIONS. [ANNO 1797. genous gas evolved by this process does not arise from the decomposition of char- coal ; because the same quantity of that substance is contained in the gas after, as before electrization. 3. The hydrogenous gas proceeds from decomposed water; because when this fluid is abstracted as far as possible from the carbonated hydro- genous gas, before submitting it to the action of electricity, the dilatation cannot be extended beyond £ its usual amount. 4. The decomponent of the water is not a metallic substance; because carbonated hydrogenous gas is expanded when in contact only with a glass tube and gold, a metal which has no power of separating water into its formative principles. 5. The oxygen of the water (when the electric fluid is passed through carbonated hydrogenous gas, that holds this substance in solution,) combines with the carbon, and forms carbonic acid. This production of carbonic acid therefore adds to the dilatation occasioned by the evolution of hy- drogenous gas. 6. There is not, by the action of the electric matter on carbo- nated hydrogenous gas, any generation of azotic gas. 7. Carbon it appears there- fore, from the united evidence of these facts, is still to be considered as an elementary body; that is, as a body with the composition of which we are unac- quainted, but which may nevertheless yield to the labours of some future and more successful analyst. XIX. Observations and Experiments on the Colour of Blood. By Wm. C. IVells, M.D., F.R.S. p. 4l6. Dr. Priestley is, I believe, the only person who has hitherto attempted to show by what means common air brightens the colour of blood, which has been for some time exposed to it*. His opinion is, that the air produces this effect by depriving the blood of its phlogiston ; for blood, according to the same author, is wonder- fully fitted both to imbibe and to part with phlogiston, becoming black when charged with that principle, but highly florid when freed from it. Various argu- ments may be brought to prove that this opinion is erroneous, even on the ad- mission of such a principle of bodies as phlogiston. It may be said, for instance, that it is contrary to the laws of chemical affinity, that the same mass should at one time convert pure into phlogisticated air, by giving out its phlogiston, and im- mediately after reconvert phlogisticated into pure air, by imbibing that principle; both which changes are supposed by Dr. Priestley to be induced by blood, on those airs. Again ; it may be urged, that since the neutral salts, and the different al- kalies, when saturated with fixed air, produce the same effect as common air on the colour of blood, if common air acts by attracting phlogiston, those other bodies must have a similar operation. But surely it cannot be thought, that the mild vo- latile alkali, which has been supposed by chemists to superabound with phlogiston, can yet attract it from blood. It appears to me however, unnecessary to bring any further arguments of this kind against the opinion of Dr. Priestley, since the fol- lowing experiments will, I expect, be thought sufficient to show, in opposition ta * Phil. Trans, for 1776.— Orig. VOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. 22$ what is taken for granted by him in the whole of his inquiry, that the alteration in- duced on the colour of blood, both by common air and the neutral salts, is alto- gether independent of any change effected by them on its colouring matter. I infused a piece of black crassamentum of blood in distilled water, and imme- diately after covered the containing vessel closely, to prevent the access of air* Having obtained by this means a transparent solution of the red matter of blood, nearly free from serum and coagulable lymph, I exposed a quantity of it to the open air in a shallow vessel, and poured an equal quantity into a small phial, which was then well closed. When the 1st portion of the solution had been exposed to the air for several hours, I decanted it into a phial, of the same size and shape as that which contained the 2d portion, and having added to it as much distilled water as was sufficient to compensate the loss it had suffered by evaporation, I now compared the 2 together, and found them to be exactly of the same colour, with regard both to kind and degree. I afterwards poured 2 other equal quantities of the red solution into 2 phials of the same size and shape. To l I added a little of a solution of nitre in water, and to the other as much distilled water. On com- paring the 2 mixtures together, I found that they also possessed precisely the same colour. Lastly, I cut a quantity of dark crassamentum of blood into thin slices, and exposed them to common air. When they became florid, I put them into a phial containing distilled water. I then took as much of the same crassamentum, which was still black, and infused it in an equal quantity of distilled water, contained in a phial similar in size and shape to the former. The 2 solutions which were thus obtained, 1 from florid blood, the other from black blood, were notwithstanding of precisely the same colour. These experiments were frequently repeated, and were attended with the same results, as often as I used certain precautions, which shall be mentioned hereafter, as the reasons for them will then be more readily under- stood than they can be at present. Assuming therefore as proved, that neither common air, nor the neutral salts (for all those I have tried are similar to nitre in this respect) change the colour of the red matter of blood ; I shall now attempt to explain the manner in which those substances give, notwithstanding, to black blood a florid appearance ; premising however some observations on the colours of bodies in general. It was the opinion of Kepler *, that light is reflected without colour from the surfaces of bodies ; which he says is easily proved, by exposing to the sun's light a number of cups filled with transparent liquors of different colours, and receiving the reflexions from them on a white ground in a dark place. Zucchius, who was younger than Kepler, but for some time his cotemporary, taught more explicitly *J-, that the colours of bodies depend, not on the light which is reflected from their anterior surfaces, but on that portion of it which is received into their internal parts, and is thence sent back through those surfaces. The following are some of the experiments on which he founded this doctrine. He exposed small round * Paralipomena in Vitellionem, p. 23 et 436. — t Optica Philos. pars I, p. 278 et seq. — Orig. 230 PHILOSOPHICAL TRANSACTIONS. [ANNO 1797. pieces of transparent glass, tinged with various colours to the light of the sun, and received what was reflected from them on white paper, in a darkened part of his room. He then found, that each glass produced 2 luminous circles, which, when the paper was sufficiently remote, were entirely separate from each other ; and that the circle which proceeded from the upper surface of the glass was altogether without colour, while that which arose from the under surface, was of the same colour as the glass exhibited, when held between the light and the eye. From these experiments Zucchius also concluded, first, that every coloured body must be in some degree transparent, since a body absolutely impenetrable to light, could only reflect the colours of other bodies, but possess none of its own ; and 2dly, that all bodies, which appear coloured when seen by reflected light, must be in some measure opake; for as the light which is reflected from their surfaces comes untinged to the eye, if that part of it which penetrates their substance were afterwards to proceed in it without impediment, no colour could be exhibited by them.* When Sir Isaac Newton began his experiments on light and colours, it was ge- nerally believed, that colours in opake bodies arise from some modification given to light, by the surfaces which reflect it. In opposition to one part of this opinion, our great philosopher maintained, that such bodies are seen coloured, from their acting differently on the different colorific rays, of which white light is composed; but having established this point beyond dispute, he seems to have admitted, with- out inquiry, that colours are produced at the surfaces of the opake bodies to which they belong. For his experiments do not necessarily lead to such a conclusion ; on the contrary, they are not more consistent with it, than they are with the opinion of Kepler and Zucchius. This opinion indeed he appears not to have known ; since he has taken for granted, what is contradicted by the experiments on which it is founded, that the tinging particles of transparent bodies reflect coloured light.-}- The very splendour of Sir Isaac Newton's discoveries in optics, has probably done some injury to this branch of knowledge; for soon after they were made public, it became a common opinion, that the subject of light and colours had been exhausted by that great man, and that no writer on it before him was now worthy of being read. The former part of this opinion has long been generally acknowledged to be unjust; but the latter part of it is still maintained by many, * The works of Zucchius seem very little known, though they contain a considerable number of ori- ginal experiments, and though it is probable that he was the inventor of the reflecting telescope. For he says (Pars 1, p. 126) it had occurred to him so early as l6l6, that the same effect which is produced by the convex object-glass of a telescope, might be obtained by reflexion from a concave mirror; and that, after many attempts to construct telescopes with such mirrors, which proved fruitless from imper- fections in their figure, he at length procured a concave mirror very accurately wrought, by means of which, and a concave eye-glass, he was enabled to prove his theory to be just. He does not mention at what precise time he constructed this telescope: but his book was printed in lo"52, 1 1 years before the publication of the " Optica Promota" of James Gregory. I have not met with any account of Zucchius, in Montucla's or Priestley's histories; in the article " telescope," in the French Encyclopedia; or in any Biographical dictionary which I have consulted. 1 Optics, book 1, part 2, prop. 10. — Orig. VOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. 231 among whom may be placed the learned Mr. Delaval. This gentleman has lately published, (in the Manchester Memoirs, vol. 2) a very elaborate treatise to prove, that the colours of opake bodies do not arise from the rays of light which they reflect from their anterior surfaces; but from that portion of it, which, having penetrated their anterior surfaces, is reflected by the opake particles which are dif- fused through their substance. But had the learned author not believed, that no European writer on colours, before Sir Isaac Newton, contained any valuable infor- mation on that subject, he would probably have discovered, that both Kepler and Zucchius had long ago maintained the very opinion which he now advances, and that they had built it on experiments similar to his own. The merit of the inven- tion of this theory belongs therefore to the great Kepler; but still much praise is due to Mr. Delaval, both for reviving and confirming it; since, though it be not free from defects in some of its parts, it affords solutions of several optical diffi- culties, which, as far as I know, admit of an explanation from no other source. Among these I regard the phenomenon which is the subject of the present inquiry. To show then, from the theory of Kepler, Zucchius, and Delaval, how common air and the neutral salts may brighten the appearance of blood, without producing any change on its colouring matter, I shall first suppose that all its parts have the same reflective power. The consequence will be, that a mass sufficiently thick to suffocate the whole of the light which enters it, before it can proceed to the pos- terior surface, and be thence returned through the first surface, must appear black; for the rays which are reflected from the first surface are without colour, and by hypothesis none can be reflected from its internal parts. In the next place, let there be dispersed through this black mass a small number of particles, differing from it in reflective power, and it will immediately appear slightly coloured; for some of the rays, which have penetrated its surface, will be reflected by those par- ticles, and will come to the eye obscurely tinged with the colour, which is exhi- bited by a thin layer of blood, when placed between us and the light. Increase now by degrees the number of those particles, and in the same proportion as they are multiplied, must the colour of the mass become both stronger and brighter. Having thus shown that a black mass may become highly coloured, merely by a considerable reflexion of light from its internal parts; if I should now be able to prove, that both common air and the neutral salts increase the reflexion of light from the internal parts of blood, at the same time that they brighten it, great pro- gress would certainly be made in establishing the opinion, that the change of its appearance, which is occasioned by them, depends on that circumstance alone. But the following observations seem to place this point beyond doubt. I compared several pieces of crassamentum of blood, which had been reddened by means of common air and the neutral salts, with other pieces of the same crassamentum, which were still black, or nearly so; on which 1 found, that the reddened pieces manifestly reflected more light than the black. One proof of this was, that the minute parts of the former could be much more distinctly seen than those of the 232 PHILOSOPHICAL TRANSACTIONS. N [ANNO 1797. latter. Now this increased reflection of light, in the reddened pieces, could not arise from any change in the reflective power of their surfaces; for bodies reflect light from their surfaces in proportion to their density and inflammability; and nei- ther of those qualities, in the reddened pieces of crassamentnm, can be supposed to have been augmented by common air, or a solution of a neutral salt in water. The increased reflexion must, consequently, have arisen from some change in their internal parts, by means of which much of the light which had formerly been suf- focated, was now sent back through their anterior surfaces, tinged with the colour of the medium through which it had passed. The precise nature of the change which is induced on blood by the neutral salts, is made manifest by the following experiment. I poured on a piece of printed card as much serum, rendered very turbid with red globules, as barely allowed the words to be legible through it. I next dropped on the card a little of a solution of nitre in water; when I observed, that wherever the solution came in contact with the turbid serum, a whitish cloud was immediately formed. The 2 fluids were then stirred together; on which the mixture became so opake, that the printed letters on the card could no longer be seen. I have not hitherto been able to devise any ex- periment which shows the exact change induced by common air; but it is evident that air must also, in some way, increase the opacity of blood, since it can by no other means increase the reflexion of light from the interior parts of that body. This theory explains another fact respecting the colour of blood, which might otherwise seem unaccountable. If a small quantity of a concentrated mineral acid be applied to a piece of dark crassamentum, the parts touched by it will for an in- stant appear florid; but the same acid, added to a solution of the red matter in water, do nothing more than destroy its colour. On examining the crassamentum, a reason for this difference of effect is discovered; for the spots, on which the acid was dropped, are found covered with whitish films. From which it seems evident, that the acid had occasioned an increase of opacity in the crassamentum, more quickly than it had destroyed its colour; and that the red matter, from having been in consequence seen by a greater quantity of light, had in that short interval ap- peared more florid than formerly. The change which, I think I have proved to take place in blood, when its colour is brightened by common air and the neutral salts, is similar to that which occurs to cinnabar in the making of vermillion. This pigment, it is known, is formed from cinnabar, merely by subjecting it to a minute mechanical division. But the effect of this division is, to interpose among its particles, an infinite number of molecules of air, which, now acting as opake matter, increase the reflection of light from the interior parts of the heap, and by this means occasion the whole dif- ference of appearance observed between those 2 states of the same chemical body. I expect however it will be said, in opposition to what I have advanced, that granting an increased reflection of light takes place from the interior parts of blood, iu consequence of the application of common air and the neutral salts, still this is VOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. 233 not a sufficient cause for the production of the colour which they occasion ; for the colour of blood, after those substances have acted on it, is a scarlet, which, agree- ably to the observation of Dr. G. Fordyce, (Elements of the Practice of Physic, p. 13) differs not only in brightness, but also in kind, from the ordinary colour of that fluid, which is a Modena red. My answer is, that there are examples, besides that to which the objection is made, of dark blood appearing florid, merely from its colouring matter being seen by means of an increased quantity of light. One is afforded by rubbing a piece of the darkest crassamentum with a proper quantity of serum; for a mixture is thus formed, in a few seconds, possessing a colour similar to that which is given to cras- samentum by common air. But here we certainly do nothing more than interpose, among the red globules, a number of the less dense particles of serum; which, in their present situation, act as opake matter, and consequently increase the internal reflections. A 2d example occurs, when we view, by transmitted light, the fine edges and angles of a piece of crassamentum in water; for, in this situation, their colour appears to be a bright scarlet, though all the other parts of the same mass are black. These facts seem sufficient to prove, that the immediate cause I have assigned for the production of the florid appearance in blood, which has been ex- posed to the action of common air and neutral salts, is adequate to the effect; but I shall advance a step farther, and show how the Modena red is converted into a scarlet. Blood, as I have found by experiment, is one of those fluids which Sir Isaac Newton has observed appear yellow, if viewed in very thin masses; book ], part 2, prop. 10. When therefore a number of opake particles are formed in it, by the action of common air and the neutral salts, many of them must be situated immediately beneath the surface. The light reflected by these will consequently be yellow ; and the whole effect of the newly-formed opake particles, on the appearance of the mass, will be the same, as if yellow had been added to its former colour, a Modena red. But Modena red and yellow are the colours which compose scarlet; Fordyce's Elements of the Practice of Physic, p. 14. I shall now relate the cautions to be observed in making the experiments, which are described in the beginning of this paper. The first is, that the blood should be newly drawn, and the weather cool. For as the solution of the red matter is not to be filtred, but must become transparent by the gradual subsiding of whatever may render it turbid, if the blood be old, or the weather warm, it will often assume, before it be clear, a dark and purplish hue. When exposed in this state to the at- mosphere in a broad and shallow vessel, its colour changes to a bright red, which however is not brighter than the proper colour of the solution. The dark purplish hue seems owing to some modification of sulphur; for the solution possessing it smells like hepatic air, particularly when agitated, and tarnishes silver held over it. Neutral salts produce no change on this colour. The 2d caution is, that the neutral salts be not added to the red solution, except when perfectly transparent; for if it be not so, the salts will render it more turbid, VOL. XVIII. H H 234 PHILOSOPHICAL TRANSACTIONS. [ANNO 17Q7. and the mixture will appear brighter, if seen by reflected light. The last I shall note is, that the red solution ought to be poured gently from the vessel in which it has been made. If it be not, as it is a mucilaginous liquor, it is apt to entangle small particles of air, which by acting as opake matter, will for some time alter the appearance of the solution. I proceed next to offer a few observations on the cause of the red colour of blood. It has of late been very generally supposed, that blood derives its colour from iron. As far as I know however, no other argument has been given in support of this opinion, than that the red matter is found to contain that metal. But there is certainly no necessary connection between redness and iron; since this metal exists in many bodies of other colours, and even in various parts of animals without co- lour, as bones and wool. More direct reasons however may be given for rejecting this opinion. 1 . I know of no colour, arising from a metal, which can be perma- nently destroyed by exposing its subject, in a close vessel, to a heat less than that of boiling water. But this happens with respect to the colour of blood. 2. If the colour from a metal, in any substance, be destroyed by an alkali, it may be restored by the immediate addition of an acid; and the like will happen from the addition of a proper quantity of alkali, if the colour has been destroyed by an acid. The colour of blood, on the contrary, when once destroyed, either by an acid or an alkali, can never be brought back. 3. If iron be the cause of the red colour of blood, it must exist there in a saline state, since the red matter is soluble in water. The substances therefore, which detect almost the smallest quantity of iron in such a state, ought likewise to demonstrate its presence in blood; but on adding Prussian alkali, and an infusion of galls, to a very saturate solution of the red matter, I could not observe, in the former case, the slightest blue precipitate, or in the latter, that the mixture had acquired the least blue or purple tint. On the whole it appears to me, that blood derives its colour from the peculiar organization of the animal matter of one of its parts; for whenever this is destroyed, the colour disappears, and can never be made to return ; which would not I think be the case, if it depended on the presence of any foreign substance whatever. I shall conclude this paper with relating several miscellaneous facts respecting the co- lour of blood, and some conclusions which may be formed from them. Dr. Priestley has mentioned, (Phil. Trans., 1776, p. 246) that the only animal fluid, besides serum, which he found to transmit the influence of common air to blood, was milk. But I have observed, that the white of an egg possesses the same property, notwithstanding its great tenacity. Now as serum contains an animal substance very similar to the white of eggs, it occurred to me as a question, whe- ther, in transmitting the influence of air to blood, it acts by its salts only, or partly by means of the substance of which I have just spoken. I took therefore a quan- tity of urine, which is known to contain nearly the same salts as serum, and hav- ing added to it as much distilled water as rendered its taste of the same pungency as that of serum, I poured the mixture on a piece of dark crassamentum of blood. VOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. 235 I then put to another piece of the same crassamentum an equal quantity of serum, and exposed both parcels to the atmosphere. The result was, that the blood in the diluted urine did not become nearly so florid as that in the serum. I have found also, that a solution of sugar in water conveys the influence of air to blood ; from which it seems probable, that milk owes its similar property to the saccharine matter which it contains. Black blood exposed to the atmosphere under mucilage of gum arabic, does not become florid. It has been said, (Fordyce's Elements of the Practice of Physic, p. 14), that neither serum, nor solutions of the neutral salts, dissolve the red matter of blood. But this induction has been made from too small a number of experiments. For saturate solutions of all the neutral salts, which I have tried, will extract, though slowly, red tinctures from blood, some of which are very deep; and neither they, nor serum, added in any proportion to a solution of the red matter in water, alter its colour or transparency, except by diluting it. The following experiments how- ever, will place this point in a clearer light. I added 1 dr. of distilled water to 1 oz. of serum, and poured the mixture on a small piece of crassamentum. On an equal piece of crassamentum I poured 1 dr. of water, and after some time added 1 oz. of serum. Each parcel therefore con- tained the same quantity of crassamentum, serum, and water; but the crassamentum on which the mixture of serum and water had been poured, communicated no tinge to it; while the other piece, to which water had been first applied, and afterwards serum, gave a deep colour to the fluid above it. I made similar experiments with crassamentum, water, and a dilute solution of a neutral salt, which were attended with the same results. Since then neither serum, nor a dilute solution of a neutral salt, will extract co- lour from blood, though they are both capable of dissolving the red matter, when separated by water from the other parts of the mass, it follows, in my opinion, that what are called the red globules consist of 2 parts, one within the other, and that the outer, being insoluble in serum or dilute solutions of neutral salts, defends the inner from the action of those fluids. It is remarkable, that microscopical obserr vations led Mr. Hewson to the same conclusion, viz. that the red globules consist of 2 parts, (Hewson's works, vol.3, p. 17) which, according to him, are an exte- rior vesicle, and an interior solid sphere. But the same writer, on the authority of other microscopic experiments, asserts that the vesicles are red. If they be so, there must exist 2 red matters in the blood, possessing different chemical properties; which is certainly far from being probable. The exterior part of the globule appears to be that ingredient of the blood on which common air and the neutral salts pro- duce their immediate effect, when they render the whole mass florid; for I have shown that they do not act on the red matter itself, and I have not found that they occasion any change in coagulated lymph or serum. The only matter then which remains to be operated on, is that which I have mentioned. It seems evident also, from what has been just stated, that there exists an animal matter in the blood, h h 2 236 PHILOSOPHICAL TRANSACTIONS. [ANNO 1797. different from the coagulable lymph, the coagulable part of the serum, the putres- cent mucilage, and the red particles, which I believe are all the kinds it has hitherto been supposed to contain. The microscopical observations of Mr. Hewson appear likewise to furnish a rea- son, why both water, and a saturate solution of a neutral salt, can extract colour from the red globules, though a mixture of those fluids be incapable of the same effect. For water applied to the red globules, separates the exterior vesicles from the red particles, which are therefore now open to the action of any solvent.* The addition however of a small quantity of a neutral salt to the water, enables the vesicles to preserve their shape, and to retain the inner spherules. -J- On the addi- tion of a greater quantity of salt, the vesicles contract, and apply themselves closely to the red particles within. J Thus far Mr. Hewson's observations extend. Let it now be supposed that the vesicles contract still more, from a further addition of salt to the water; the consequence must be, that as the internal particles are in- compressible, the sides of the vesicles will be rent, and their contents exposed to the action of the surrounding fluid. Both water and a strong solution of a neutral salt may therefore destroy the organization of the vesicles, though in differ- ent ways, and thus agree in bringing the red matter in contact with a solvent ; while a mixture of those 2 fluids, namely, a dilute solution of a neutral salt, will, by hardening the vesicles, increase the defence of the red matter against the action of such substances as are capable of dissolving it. But all reasoning founded on experiments with microscopes ought perhaps to be regarded as, in great measure, conjectural. XX. An Account of the Trigonometrical Survey, carried on in 1795, 1796, by Order of the Marquis Cornwallis, Master General of the Ordnance. By Col. Edw. Williams, Capt. Wm. Mudge, and Mr. Isaac Dalby. Communicated by the Duke of Richmond, F. R. S. p. 432. According to the resolution expressed in the account of the trigonometrical survey, printed in the Phil. Trans, for the year 1795, we now communicate to the public, through the same channel, a further account of its progress. On referring to the above paper, it will be found that, for the prosecution of this undertaking, a design was formed of proceeding to the westward, with a series of triangles, for the survey of the coast. This intention has been carried into effect ; and as the small theodolite, or circular instrument, announced in our former communication as then in the hands of Mr. Ramsden, was finished early in the summer of 1795, we are enabled to give a series of triangles extending, in conjunction with those before given, from the Isle of Thanet, in Kent, to the Land's End. In the composition of the following account, we have adhered to the plan adopted in the last, of giving the angles of the great triangles, with their variations ; and we have, with as much * Hewson's Works, vol. iii. p. 17.— — f Ibid. p. 40. % Ibid. p. 31. — Orig. VOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. 237 brevity as possible, inserted a narrative of each year's operations. This will be found however to extend only to the 1st part, or that containing the particulars of the survey in which the great instrument alone was used. The remaining contents of this portion of the work, are necessarily confined to the angles of the principal and secondary triangles, with the calculations of their sides, in feet ; and likewise such data as have no connection with the computations of latitudes and longitudes. The 2d part contains an account of a survey carried on in Kent, in the years 1795 and 1796, with the small instrument, for completing a map of the eastern and southern parts of that county, for the use of the Board of Ordnance, and the military commanders on the coast. In the 1st part will be found an article, for which we are indebted to Dr. Maskelyne, the Astronomer Royal. It contains his demonstration of M. de Lambre's formula, in the Connoissance des Temps of 1793, for reducing a distance on the sphere to any great circle near it, or the contrary. The practical rule thence derived, for reducing the angles in the plane of the hori- zon, to those formed by the chords, is very useful, and will considerably abridge the trouble which must necessarily arise in computing the chord corrections by any former method. Some angles are next registered as taken at the best stations in Devonshire, and other points in the west of England, in the year 1795- The survey then extends farther westwards in the next year 17 96. . It is here observed that, to make obser- vations for the purpose of hereafter determining the longitude and latitude of the Lizard, was a principal object in this year's operations ; and as this headland seems to offer itself as very convenient for a station, it will be right to assign the reasons for not having chosen one upon it. As no other spot but Hensbarrow Beacon could be found in that part of Corn- wall proper for a station, it became necessary to fix on the Deadman, or Dodman, for another point in the series. From this place no part of the land within 4 miles of the Lizard can be seen, as the high ground about Black Head, which is to the eastward of the latter, is nearly in a line between them, and is also much higher than both. It will be perceived however, that no evil can result from the want of such a station, as the light-houses and the naval signal-staff at the Lizard, have been intersected from several stations. The precise spot on which Mr. Bradley made his observations in the year 1769, for ascertaining the longitude and latitude of this headland, was pointed out by the person having the care of the light-houses, who well remembered the common particulars relating to his operations : such measurements were made from the light-houses to this spot, as may enable us, at a future period, to compare the results from the data afforded by the trigonometri- cal operation, with those deduced from the astronomical observations made by the above gentleman. It may be also mentioned, that angles were at the same time taken at the western light-house and signal-staff, for the purpose of finding the situation of the Lizard Point. 238 PHILOSOPHICAL TRANSACTIONS. [ANNO 17 Of. We are now to speak of the most important business performed this year ; that of making observations to determine the distance of the Scilly Isles from the Land's End. To do this as accurately as possible, it became necessary to find stations affording the longest base. The hill near Rosemergy, called the Watch, and the station near St. Buryan, are certainly the most advantageous places, because all the islands can be seen from both ; but we could not avail ourselves of the former, as difficulties almost insuperable would have attended an attempt to get the instrument upon it. Another station was therefore selected, on Karnminnis, near St. Ives ; a spot as well situated as the place spoken of, provided all the islands could be seen : this however does not prove to be the case, St. Martin's Day-Mark being the only object in the Scilly Islands visible from Karnminnis. From the stations near the Land's End, Sennen, and Pertinney, as well as that above-mentioned, St. Buryan, St. Agnes' Light-house, and 2 objects in St. Mary's, were observed ; and as the means by which all their distances are determined, ex- cept those of the Day-Mark, from the shortness of the bases, though the longest that could be found, are exceptionable, while we were engaged in that part of the operation now spoken of, the air was so unusually clear, that we could sometimes, with the telescope of the great theodolite, discover the soldiers at exercise in St. Mary's island.. In the present and former seasons, such stations were selected and observed, as were judged to be proper for the future use of the small instrument ; and as we had experienced, in the early stage of this survey, much delay and dis- appointment from the white lights not being always seen when fired on distant stations, we have since substituted lamps and staffs in their stead. The operations of the present year were continued till October, when the party returned to London. A list is here given of the angles observed in this quarter in the year 17 Q6. After which is set down the demonstration of M. de Lambre's Formula in the Con- noissance des Temps of 1793, for reducing a distance on the sphere to any great circle near it, or the contrary ; by Nevil Maskelyne, d. d. f. r. s. and Astronomer Royal. Put A = angle subtended by 2 terrestrial objects ; a = the same reduced to the horizon ; h, A the 2 apparent altitudes : if either is a depression, it must be taken negative. By spherics, c, a = c, a . «, h . c, A + s, h . s, A. Put A = a -f- da, where da signifies a — a, and not their differential. By trigonometry c, a = c, a . c, da — s, a . s, da = c, a X (l — vs, da) — s, a . s, da = c,a — c, a X Is1, 4- da — s, a . s, da (by theorem above) = c, a . c, h . c, A -f- s, h . s, h '.' s, da + Is1, ^da .'t, a = 't, a — 't, a . c, h . c, A — s, h . s, h X cosec. a = t\ a — 't, a X CK, (h — A) + -Kj (h + A) — cosec. a X (ic, (h — h) — ±c, (h -f h)) because t\ a = +% ±a — ±t, 4-a ; and cosec. a = ^t\a + ±t, -j-a) = 0& i« - M *«) X (1 - -K, (h - k) - ±c, (h + h)) - (*%ia -f- ->./, ±a) X U-c, (h — h) — ic, (h + h)) = ft, -j-a x (1 - c, (h - A)) — ±t, ±a x (1 — c, (h + A)) = +% ±a X vs, (h — A) — ±t, \a X vs, (h -f- A) = %+a . s\ 4. (h - A) - t, +a . s\ 4. (h + A). VOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. 230 Put n = % \a . s>, ± (h — h) — t, ±a . s*, i (h -f- h). We shall have s, da -f- 2s2, ±da ,'t, a = n; and s, da = n — 2.s2, -^da . t' , a. But s, da — Is, ^da . c, \da ; , s, da n — 2s%, Ada . '#- a ' s -*-da — - = ~ * * ' ' ■ 2c, \da " 2c, Ida and s, da = n - 2 n — 4» . s1, \da . t', a + 4s4, Ida . 'tz, a because ( — -^ ) — 4x(i-i5TPo — j ± n . s , \da . t,a — n . s , \da . t, a -j- s4, ±da . 'f, a = n — 4-rc2 . t' , a — -±-n2 .'t,a . s1, ±da -f 2rc . ' Feet. And Longship's Light-house.. = 27883 J the angle at Pertinney, augmented for calculation, r the Day- Mark = 12° 17' 30" ) We get the between the Longship's Light-house and \ St. Agnes' Light-house = 6 15 25 J distance of ft. tag**. Light-house tan .... {g^^^tai- {2$gZ§!tf** Calculating also, with the distances of the two other objects in the Scilly Isles and likewise those of Sennen steeple, and the stone near the Land's End from Pertinney, with the included angles at the same station, we get Feet. Miles. f Day-Mark = 139521 = 26.4,3 Sennen steeple from }"£■ ASnJs/ Light-We = l6&25 5 = 31>40 r j Flagstaff in St. Mary s = 157912 = 29.05 (. Windmill in St. Mary's = 155299 = 29.41 f Day-Mark = 135343 = 25.63 Stone near the Land's End from } £• AS"5S' Lj?h£;ho^e = l6210° = 30.7 J Flagstaff in St. Mary s = 153744 = 29.ll (.Windmill in St. Mary's == 151138 = 28.6'3 Of the Scilly Isles, Menawthen is the nearest to the Land's End, being about l^rV miles eastward of the Day-Mark ; and the cluster of rocks, called the Bishoj. and his Clerks, the most remote, being 3f miles west of St. Agnes' Light-house. Combining therefore the above particulars with those distances, we may conclude, 1 1 2 244 PHILOSOPHICAL TRANSACTIONS. [ANNO 1/97. that the nearest part of the Scilly Isles is about 24.7 miles from the Land's End, and the farthest nearly 34. This account of the trigonometrical survey then relates to that carried on in Kent, in the years 1795 and 1796, with the small circular instrument. The instrument used in this survey was announced in the Philos. Trans, for 1 795. It was made by Mr. Ramsden ; and was about half the size of his large theodolite, or circular in- strument, with which were taken the horizontal angles, but nearly similar to it in all its parts. This instrument, on account of its portable size, may very readily be taken to the tops of steeples, towers, &c. and is therefore extremely well adapted to the uses for which it was intended. Then follows a list of the situations of the stations on which observations were made with the small circular instrument, in the summer of the year ] 7Q5 ; with the triangles for determining the distances of the stations. As the station on the Keep of Dover Castle, in 1 787, was directly over the steps of the Turret, a new point was chosen about 6^ feet from the former, where the instrument could stand conveniently : this new point is about 2.8 feet farther from Folkstone Turnpike, and 1 foot farther from Paddlesworth, than the point marking the old station. From General Roy's account of the trigonometrical survey in 1787, we have Dover Castle from Folkstone Turnpike 31554.6 > f from Paddlesworth 42561.2 J Now, augmenting those distances in the proportion of 141 747 to 141753 (see Phil. Trans, vol. 80, p. 595, and the vol. for 1795, P- 508), we get 31556, and 42563 feet; to which adding 2.8, and 1, respectively, we have The new point on Dover Castle from Folkstone Turnpike 31558.8 ") f from Paddlesworth 42564 J In order to obtain the distance between Waldershare and Dover Castle from those new sides, or distances, the three angles of the following triangle were very carefully taken. f Dover Castle 3° 49' 16" 3° 49' 15" ) 1 1 Folkstone Turnpike 36 6 31 36 6 30 > for computation. I Hawkinge 140 4 16 140 4 15 J The 3d angles of the next 2 triangles were not observed : Hawkinge 44° 23' 30" Dover Castle 73 53 44 Waldershare 6l 42 46 Dover Castle 62 24 7 Paddlesworth (the station of 1787) 32 36 9 Waldershare 84 59 44 Feet. By the first 2 triangles, Dover Castle from Waldershare 23019 4 1 5 mean distanCGt From the latter 23021.5 J * , u , • r, f Dover Castle 28976. And Hawkinge from.- { Waldershare 3l6l6. Finally are deduced the distances of the objects intersected in the survey with the small circular instrument, from the meridian of Greenwich, and from the perpen- dicular to that meridian. Also their latitudes and longitudes. At Folkstone turn- pike, the bearing of the station on Dover Castle in 1787, from the parallel to the { { VOL. LXXXV1I.] PHILOSOPHICAL TRANSACTIONS. 245 meridian of Greenwich is 65° 52' &6" n.e. The new point on the Keep is 6-l feet north-eastward from the old one, which will subtend an angle at Folkstone turn- pike of about 38/;; therefore the new station bears 65° 52' 8" n.e. The bearing of the centre of Tenterden steeple from Allington Knoll, is nearly the same as that of the station in 1787, or 85° 47' 25" s.w : but the distances of those stations (Folkstone turnpike and Allington Knoll), from the meridian of Greenwich, and its perpendicular, are augmented in the proportion of 141747 to 141753, for obtaining the distances in the 3d arid 4th columns of the following table : Folkstone turnpike being 274Q79 and 1 37220 ; and Allington Knoll 2 1 9935 and 144038 feet, respectively, from the meridian, and its perpendicular. Bearings and Distances of the Stations. Bearings from the Parallels to the Meridian of Greenwich. At Folkstone turnpike. Dover Hawkinge At Dover. Paddlesworth Waldershare Blngswold At Waldershare. Shore Mount Pleasant Wingham Hardres Hawkinge Fiingswold Near the shore. Ringswold 65 52 8 ne 29 45 38 n e 81 30 42 sw 36 24 53 nw 30 21 52 ne 39 54 35 ne 11 56 19 ne 16 36 24 nw 74 21 9 nw 17 53 sw 37 43 ne 3 16 15 sw At Dover. St. Radigund's Abbey . . Hougham steeple Gunston steeple St. Margaret's steeple . . South Foreland light- > house j At Waldershare. Barham windmill Elham windmill Upper Deal chapel .... •Deal Castle Watch-house near the 1 shore / Sandown Castle Walmer steeple Ripple steeple Waldershare steeple. . . . Eastry steeple Ash steeple Minster steeple Woard steeple Sandwich highest steeple Wingham steeple. . . Goodneston steeple . 70 10 31 NE 61 10 63 66 5 4 nw 19 22 sw 43 2 nw 54 43 ne 0 4 N w 14 39 sw 17 33 NE 9 16 NE 51 8 1 52 85 2 37 se 56 NE 30 NE 50 NE 20 NE 30 46 ne 44 29 n e 24 56 ne 1 1 33 NE 19 14 NE 6 36 nw 16 21 NW Distances frommeri. Feet. 303730 2706O5 262004 290114 315783 317545 302716 279533 248180 Distances from perp. Bearings from the Parallels to the Meridian of Greenwich. Distances from meri. Distances from perp. Feet. 124318 1343/6 130553 105792 103830 72997 46190 70315 94046 Near the shore. Mount Pleasant At Mount Pleasant. Wingham 28 50' 58 43 51 31 82 23 48 18 10 37 52 52 37 77 3 23 2 3 23 S5 47 25 32 34 49 2 2 48 22 37 5 NW SW SW NW SW NW SE sw NW NE NE Feet. 272918 247060 192302 221269 230102 Feet. Chislet 50168 At Wingham. Chislet Hardres Beverley Park At Beverley Park. At Allington Knoll. Tenterden 62852 Wye Down 100797 106701 119636 Brabourn Down 287597 2883 H 303189 315148 315145 278573 284430 317056' 321842 321314 321721 ."318338 302867 205235 300393 29306'9 301155 308967 307187 27S007 281915 Interior 123777 130455 115226 115408 120721 93852 137246 9'2237 91768 108498 84365 97239 97534 1 03390 82166 70165 51113 78042 71279 72725 82343 Objects. At Waldershare . Littlebourn steeple .... Canterbury cathedral . . At Ringswold. Mongebam steeple .... Norbourn steeple Woodnesborough steeple Near the Shore. Ramsgate windmill St. Lawrence steeple . . At Mount Pleasant. Birchington steeple .... St. Nicholas steeple .... Stormouth steeple At Wingham. The South Reculver. . . . Hearne windmill ...... Blean steeple Wickham steeple Bridge windmill Nackington steeple Chillingdon windmill . . Preston steeple Shottenden windmill . . Ickham steeple 27 39 59 nw 278100 49 51 48 nw 248198 21 30 34 nw 31l6ll 31 52 45 nw 307623 29 51 29 NW 299693 12 13 43 NE 321363 7 30 6 NE 320817 20 17 12 NW 298729 78 0 9 NW 286391 65 26 52 sw 283143 8 3 15 NW 274346 34 59 11 NW 260191 76 41 i 1 NW 241261 77 21 44 nw 570923 j5 21 3 sw 260132 69 29 17 sw 249854 28 0 30 SE 286591 5 6 13 NW 278891 83 42 1 sw 212206 89 45 57 SAV 271533 70860 60458 93243 90710 75800 50817 48148 35403 42721 55132 33663 42679 61259 68384 83723 81418 83586 63124 77748 70348 246 PHILOSOPHICAL TRANSACTIONS. [anno 1797. Bearings from die Parallels to the Meridian of Distances Greenwich. from meri. At Hardres. Harbledown steeple. . . . Stuny steeple West Stone-street 1 windmill J Stelling windmill On Westwell Down. Ashford steeple Brook steeple Willsborough steeple . . Kingsnorth steeple Shadoxhurst steeple .... 14 15 0 NW 15 26 36 NE 35 46 24 sw 26 1 10 sw 24 53 15 se 6'3 10 25 se 33 0 39 se 12 49 1 se 7 20 54 sw Feet. 241955 266619 ;36cS70 242003 200728 219234 206797 199037 167830 Distances from perp. Feet. 69535 63499 109743 106700 11 8961 114417 123109 130400 135476 Bearings from the Parallels to the Meridian of Distances Distances Greenwich. from meri. from perp. On Westwell Down. 0 t Kennington steeple .... JO 34 14 se At Allington Knoll. Great Chart steeple .... 52 21 16 nw Westwell steeple 31 46 42 nw Pluckley steeple 53 27 50 n w Eastwell steeple 25 17 49 nw Charing steeple 37 58 49 nw Allington steeple J25 0 2 n e Lymne steeple 81 23 44 se Mersham steeple '22 32 14 n w Monks-Horton steeple. . 46" 23 19 ne Feet. 204869 190572 i94i:08 1735H 20094s 1 82959 221344 235914 214269 237605 Feet. 111131 121389 102510 109641 103951 96677 141017 146456 130383 127204 Bearings and Distances of the Stations and Interior Objects, intersected in \7§6. At Goudhurst. Boughton Malherb . . Bidenden Hartridge At Fairlight Down. Silver Hill 54 59 23 ne 88 49 3 ne 79 43 33 ne 34 28 24 nw 159321- 147431 95480 131744 At Fairlight Down. Iden steeple Brede steeple At Allington Knoll. Stone Crouch Warehorn steeple. . . . 33 33 48 ne 13 48 32 nw 57 3 23 sw 72 50 14 sw 168454 138116 176642 193071 180711 197485 172082 152324 At Goudhurst Frittenden steeple . . . Linton steeple Chart Sutton steeple . Sutton windmill Ulcomb steeple Headcorn windmill . . . Staplehurst Cranbrook steeple . . . At Fairlight Down. Bolvenden steeple . . . Beckley steeple Peasemarsh steeple . . , Whittersham steeple , Sandhurst steeple. Winchelsea steeple . . , Icklesham steeple . . , At Allington Knoll. Bethersden High Halden , Orleston steeple Woodcburch steeple Warehorn steeple Brookland steeple 15 96 41 +7 57 51 71 1 1 25 SI 17 50 41 69 81 •6 7'-' 42 9 23 NE 32 17 NE 16 23 NE 28 17 NE 18 3 NE 54 53 ne 49 3 NE 8 27 SE 59 36 NE 7 43 NE 11 9 NE 13 46 NE 26 59 NW 39 28 NE 12 28 nw 1 1 15 NW 4f 1 NW 50 21 sw 57 22 nw 14 sw 2 sw 50 19 135894 117510 133757 138534 147633 140758 127216 123602 145513 144072 158458 162307 127277 164181 156031 173469 164672 196655 177569 193071 192410 Interior 123079 92425 95234 96169 94491 111015 116176 138488 155271 179830 1 86395 169704 167613 201501 204073 126373 136054 145317 144000 152324 174253 Objects. At Allington Knoll. Old Romney steeple . New Romney steeple . At Boughton Malherb. Benenden steeple At Silver Hill. Brasses windmill ...... At High Nook. New Church steeple . Ivy Church steeple . . . St. Mary's steeple . . . At Lydd. Playden steeple At Westwell. Lenham steeple Egerton steeple Smarden steeple Turret on Romden stables At Stone Crouch. Appledore steeple . . Snave steeple Snargate steeple .... East Guildford steeple 21 25 40 57 82 78 M 63 S6 51 56 se 65 66 6 3 44 sw 41 50 sw 207322 217098 12 54 sw 129542 7 4 SE 123521 43 31 nw 52 46 sw 53 12 sw 214018 205170 204756 1 0 NW 169333 25 45 nw 38 J4 sw 47 14 sw 18 54 sw 165089 167621 157842 163521 33 49 NE 22 1 NE 35 7 NE 54 4 sw 182243 200828 193068 174746 176759 178460 150187 187554 156687 168562 170287 187207 87178 102243 1 19273 119970 102595 I60993 16*969 187750 Names of Objects. Latitudes and Longitudes of Objects intersected in 1795 Names of Objects. Latitude. The Belvidere inWalder- } share park \ Ringswold, or Kingswold ) steeple ) Upper Hardres steeple . . Chislet steeple Latitude. Longitude east from Greenwich. In degrees. In time. 51 11 13 1 15 39 m. s. 5 2.6 51 11 8 1 22 20 5 29.3 51 13 1 1 4 40 4 19 51 20 4 1 11 24 4 45.6 St. Radigund's Abbey .... Hougham steeple Gunston steeple St. Margaret's steeple .... South Foreland light-house Barham windmill 7 56 6 50 9 18 9 14 8 21 12 52 Longitude east from Greenwich. In degrees. In time. 0 / // m. s. 1 14 44 4 58.9 1 15 4 5 0.3 1 19 0 5 16 1 22 7 5 28.5 1 22 6 5 28.4 1 12 41 4 50.7 VOL. LXXXVII.] Names of Objects. Elham windmill Upper Deal Chapel .... Deal Castle Watch-house near the shore Sandown Castle Walmer steeple Ripple steeple Waldershare steeple .... Eastry steeple Ash steeple Minster steeple Woard steeple Sandwich highest steeple. . Wingham steeple Goodneston steeple Littlebourn steeple Canterbury cathedral .... Mongeham steeple Norbourn, orNorthbourn 1 steeple / Woodnessborough, or ") Woodnesbor. steeple J Ramsgate windmill St. Lawrence steeple .... Birchington steeple St. Nicholas steeple Stourmouth, or Stor- ") mouth steeple / The South Reculver Latitude. PHILOSOPHICAL TRANSACTIONS. Names of Objects. 5 44 13 2 13 5 10 21 14 18 15 29 12 12 11 15 14 44 16 44 1.9 50 15 23 16 30 16 21 14 45 16 40 18 26 12 53 51 13 18 51 14 47 51 51 51 .5 1 54 51 19 49 20 16 22 25 21 15 19 8 22 47 Longitude :ast from Greenwich. In degrees. In time. 0 / // m. s. 1 14 1 4 56.1 1 22 44 5 30.9 1 23 59 5 35.9 1 23 46 5 35.1 1 23 59 5 35.9 1 23 8 5 32.5 1 19 0 5 16 1 16 59 5 7-9 1 18 26 5 13.7 1 16 34 5 6.3 1 18 46 5 15.1 1 20 41 5 22.7 1 20 15 5 21 1 12 38 4 50.5 1 13 26 4 53.7 1 11 1 4 44.1 1 4 53 4 19-5 1 21 18 5 25.2 I 20 17 5 21.1 1 18 16 5 13.1 1 24 4 5 36.3 1 23 56 5 43.7 1 16 IS 5 4.8 1 14 57 4 59-S 1 14 3 4 56.2 1 11 50 4 47.3 Latitudes and Longitudes Linton steeple Sutton windmill . . . Chart Sutton steeple Lenham steeple . . . Romden stables . . . Smarden steeple . . . Bethersden steeple . Rolvenden steeple . Beckley steeple . . . Bidenden steeple . . . Headcorn windmill . Ulcomb steeple . . . Staplehurst steeple . Cranbrook steeple . Egerton steeple . . . Frittenden steeple . Snargate steeple . . . Snave steeple Warehorn steeple . Orleston steeple . . . Winchelsea steeple . 51 13 51 12 51 12 51 14 51 8 51 8 51 7 51 3 50 59 51 7 51 10 51 13 51 9 51 5 51 11 51 8 51 51 51 51 4 50 55 24 0 30 40 2 2.7 46 0 36 9 2 24.6 56 0 34 54 2 19.6 13 0 43 6 2 52.4 49 0 42 36 2 50.4 57 0 41 8 2 44.5 45 0 45 10 3 0.7 3 0 37 50 2 31.3 1 0 37 24 2 29.6 3 0 38 23 2 33.5 21 0 36 41 2 26.7 1 0 38 31 2 33 30 0 33 9 2 12.6 50 0 32 10 2 8.7 44 0 43 43 2 54.9 20 0 35 24 2 21.6 23 0 50 10 3 20.7 1 0 52 12 3 28.8 27 0 50 13 3 20.9 36 0 51 10 3 24.7 26 0 43 34 2 54.3 Hearne windmill Blean steeple Wickham steeple Ickham steeple Bridge windmill Nackington steeple Chillingdon windmill Preston steeple Shottenden windmill Harbledown steeple .... Sturry steeple West-Stone-street windm. Stelling windmill Ashford steeple Brook steeple Willsborough steeple Kingsnorth steeple Shadoxhurst steeple Kennington steeple Great Chart steeple Westwell steeple Pluckley steeple Eastwell steeple Charing steeple Allington, or Aldington 1 steeple J Lymne steeple Mersham steeple Monks Horton steeple. . . . of Objects intersected in Sandhurst steeple Whittersham steeple .... New Church steeple .... Ivy Church steeple St. Mary's steeple East Guilford steeple .... Appledore steeple Old Romney steeple .... New Romney steeple .... Playden steeple Brookland steeple Iden steeple Brede steeple Benenden steeple Brasses windmill Icklesham steeple Boughton Malherb steeple Peasemarsh steeple ...... Woodchurch steeple High Halden steeple .... u ititude. 0 51 21 20 51 18 19 51 17 5 51 17 47 51 14 35 51 14 59 51 14 30 51 17 55 5! 15 41 51 16 58 51 17 55 51 10 22 51 10 51 51 8 56 51 9 38 51 8 14 51 7 3 51 6 14 51 10 12 51 8 33 51 11 39 51 10 30 51 11 23 51 12 37 51 5 16 51 4 20 51 7 1 51 7 30 1796. 51 51 51 51 51 1 3 0 39 2 42 0 45 0 29 50 57 50 51 1 47 50 59 25 50 59 7 50 57 46 50 59 51 50 58 50 50 56 7 51 3 54 50 57 46 50 55 1 51 12 51 50 57 54 51 4 51 51 6 11 Longitude east from Greenwich. In degress. In time. 0 / // m. s. 1 8 6 4 32.4 1 3 4 4 12.3 1 10 48 4 43.2 1 10 7 4 40.5 1 7 55 4 31.7 1 5 14 4 20.9 1 14 49 4 59.3 1 12 54 4 51.6 0 55 25 3 41.7 1 3 13 4 12.9 1 7 5 4 28.3 1 I 45 4 7 1 3 6 4 12.4 0 52 18 3 29-2 0 57 8 3 48.5 0 53 52 3 35.5 0 51 49 3 27.3 0 48 53 3 15.5 0 53 17 3 33.2 0 49 39 3 18.6 0 50 39 3 22.6 0 45 14 3 0.9 0 52 24 3 29.6 0 47 44 3 10.9 0 57 36 3 50.4 1 1 22 4 5.5 0 55 47 3 43.1 1 1 53 4 7.5 0 33 4 0 42 10 0 55 38 0 53 18 0 53 11 0 45 21 0 47 22 0 53 50 0 56 22 0 43 56 0 49 58 0 43 43 0 35 49 0 33 41 0 32 3 0 40 29 0 41 34 0 41 7 0 46 12 0 42 52 END OF THE EIGHTY- SEVENTH VOLUME OP THE ORIGINAL. 248 PHILOSOPHICAL TRANSACTIONS. [anno 1798. I. The Bakerian Lecture. Being Experiments on the Resistance of Bodies moving in Fluids. By the Rev. S. Vincey A.M.y F. R. S., fife, Anno 17 98. Vol. LXXXV1I1. p. I. In a former paper on the motion of fluids, I stated the difficulties to which the theory is subject, and showed its insufficiency to determine the time of emptying vessels, even in the most simple cases ; I also proved, by actual experiments, that in many instances there was no agreement between their results and those deduced from theory. The great difference between the experimental and theoretical con- clusions, in most of the cases which respect the times in which vessels empty them- selves through pipes, necessarily leads us to suspect the truth of the theory of the action of fluids under all other circumstances. In the doctrine of the resistances of fluids, we see strong reasons to induce us to believe, that the theory cannot gene- rally lead us to any true conclusions. When a body moves in a fluid, its particles are struck by the body ; and in our theoretical considerations, after this action, the particles are supposed to produce no further effect, but are conceived to be as it were annihilated. But in fact this cannot be the case ; and what we are to allow for their effect afterwards, is beyond the reach of mere theoretical investigation. What- ever theory therefore we can admit, must be that which is founded on such experi- ments as include in them every principle which is subject to any degree of uncertainty. We must therefore have recourse to experiments, in order to establish any conclu- sions on which we may afterwards reason. In the paper above mentioned, I de- scribed a machine to find the resistances of bodies moving in fluids ; since which time, I have made a variety of experiments with it, on bodies moving both in air and water, and I have every reason to be satisfied of its great accuracy. In this paper, I propose to examine the resistance which arises from the action of non- elastic fluids on bodies. This subject divides into 2 parts : we may consider the action of water at rest on a body moving in it, or we may consider the action of the water in motion on the body at rest. We shall first give the result of our experiments in the former case, and compare them with the conclusions deduced from theory. Now the radius of the axis of the machine used in these experiments was 0.2117 in. the area of the 4 planes was 3.73 in. the distance of their centres of resistance from the axis was 7.57 in. and they moved with a velocity of 0.66 feet in a second. The first column of the following table exhibits the angles at which the planes struck, the fluid ; the 2d column shows the resistance by experiment, in the direction of their motion, in Troy ounces ; the 3d column gives the resistance by theory, assuming the perpendi- cular resistance to be the same as by experiment ; the 4th column shows the power of the sine of the angle to which the resistance is proportional. Angle. Experiment. Theory. | Power. 10° 0.0112 0.0012 1.73 20 0.0364. 0.0093 1.73 30 O.O/69 O.0290 1.54 40 0.1174 O.O616 1.5* 50 0.1552 0.10 13 1.51 60 0.1902 0.1476 1.38 70 0.2125 0.1926 I. +2 80 0.2237 0.22 i 7 2.41 90 0.2321 0.2321 VOL. LXXXVIII.] PHILOSOPHICAL TRANSACTIONS. 24Q The 4th column was thus computed : Let s be the sine of the angle to radius unity, r the resistance at that angle, and suppose r to vary as sm; then lm : sm :: 0.2321 : r, hence, sm = J , and consequently m = -g* ; ~~ °s' ' -; and, by substituting for r and s their several corresponding values, we get the respective values of m, which are the numbers in the 4th column. Now the theory supposes the resistance to vary as the cube of the sine ; whereas, the resistance decreases from an angle of Q0°, in a less ratio than that, but not as any constant power of the sine, nor as any function of the sine and cosine, that I have yet discovered. Hence, the actual resistance is always greater than that which is deduced from theory, assuming the perpendicular resistance to be the same; the reason of which, in part at least, is, that in our theory we neglect the whole of that part of the force which, after resolution, acts parallel to the plane ; whereas, from the experiments which will be afterwards mentioned, it appears that part of that force acts on the plane ; also, the resistance of the fluid which escapes from the plane, into the surrounding fluid, may probably tend to increase the actual resistance above that which the theory gives, in which that consideration does not enter; but, as this latter circum- stance affects the resistance at all angles, and we do not know the quantity of effect which it produces, we cannot say how it may affect the ratio of the resistances at different angles. In theory, the resistance perpendicular to the planes is supposed to be equal to the weight of a column of fluid, whose base = 3.73 in. and altitude === the space through which a body must fall to acquire the velocity of 0.66 feet; now that space is 0.08124 in. consequently the weight of the column = 0.1598 Troy oz. ; but the actual resistance was found to be = 0.2321 oz. Hence, the actual resistance of the planes: the resistance in our theory :: 0.2321 : O.1598, which is nearly as 3:2. I am aware that experiments have been made on the resistances of bodies moving in water, which have agreed with our theory. An extensive set was instituted by D'Alembert, Condorcet, and Bossut, the result of which very nearly coincided with theory, so far as regards the absolute quantity of the perpendicular resistance. Their experiments were made on floating bodies, drawn upon the fluid by a force acting on them in a direction parallel to the surface of the fluid. There can be no doubt but that these experiments were very accurately made. The experiments here re- lated were also repeated so often, and with so much care, and the results always agreed so nearly, that there can be no doubt but that they give the actual resistance to a very considerable degree of accuracy. In our experiments, the planes were im- mersed at some depth, in the fluid ; in the other case, the bodies floated on the surface ; and I can see no way of accounting for the difference of the resistances, but by supposing that, at the surface of the fluid, the fluid from the end of the body may escape more easily than when the body is immersed below the surface ; but this I confess appears by no means a satisfactory solution of the difficulty. The VOL. XVIII. K K 250 PHILOSOPHICAL TRANSACTIONS. [ANNO 1798. resistances of bodies descending in fluids manifestly come under the case of our experiments. Two semi-globes were next taken, and made to revolve with their flat sides for- wards. The diameter of each was 1 . 1 inc. the distance of the centre of resistance from the axis was 6.22 inc. and they moved with a velocity of 0.542 feet in a second; and the resistance was found to be 0.08339 oz. by experiment. By theory, the resistance is 0.05496 oz.; hence, the resistance by experiment : the resistance by theory :: 0.08339 : O.05496, agreeing very well with the above-mentioned propor- tion. But, when the spherical sides moved forwards with the same velocity, the resistance was 0.034 oz. Hence, the resistance on the spherical side of a semi- globe : resistance on its base :: 0.034 : 0.08339; but this is not the proportion of the resistance of a perfect globe to the resistance of a cylinder of the same diameter, moving with the same velocity, because the resistance depends on the figure of the back part of the body. • I therefore took 2 cylinders, of the same diameter as the 2 semi-globes, and of the same weight; and, giving thein the same velocity, I found the resistance to be O.07998 oz. ; therefore the resistance on the flat side of a semi-globe : the resist- ance of a cylinder of the same diameter, and moving with the same velocity :: 0.08339 : O.07998. This difference can arise only from the action of the fluid on the back side of the semi-globe, moving with its flat side forwards, being less than that on the back of the cylinder, in consequence of which the semi-globe suffered the greater resistance. The resistance of the cylinders, thus determined directly bv experiment, agrees very well with the foregoing experiments. The resistance, cteteris paribus, varies as the square of the velocity very nearly, and may be taken so for all practical purposes, as I find by repeated experiments, made both on air and water, in the manner described in my former paper. Hence, for different planes, the resistance varies as the area X the square of the velocity. Now the resistance of the planes whose area was 3.73 inc. moving with a velocity of 0.66 feet in a se- cond, was found to be == 0.2321 oz. Also, the area of the 2 cylinders was 1 .9 inc. and their velocity was 0.542 feet in a second; to find therefore the resistance of the cylinders from that of the planes, we have O.66'2 X 3.73 : 0.542* X 1.9 :: 0.2321 oz. : 0.07973 oz. for the resistance on the cylinders, differing but very little from O.07998 oz. the resistance found from direct experiment. Now, to get the resistance on a perfect globe, we must consider, that when the back part is spherical, the resistance is greater than when it is flat, in the ratio of 0.08339 : 0.07998 ; hence the resistance on a globe : the resistance on a semi-globe in the same ratio; but the resistance on the semi-globe was 0.034 oz. hence, O.O7998 : 0.08339 :: 0.034 oz. : 0.0354 oz. the resistance of a globe; consequently, the resistance of a globe : the resistance of a cylinder of the same diameter, moving with the same velocity in water :: 0.0354 : O.07998 :: 1 : 2.23. We proceed next to compare the actual resistance of a globe with the resistance assumed in our theory. In the first place, the absolute quantity of resistance has VOL. LXXXVIII.] PHILOSOPHICAL TRANSACTIONS. 251 been found to be greater than that which we use in theory, in the ratio of 0.232 J : 0.1 5()8 ; but, by theory, the resistance of the globe : the resistance of the cylinder :: 1 : 2, or as 1.115: 2.23; hence, by theory, we make the resistance of the globe too great, in the ratio of 1.115 : 1 ; and it is too small, from the former considera- tion, in the ratio of O.1598 : 0.2321 ; therefore the actual resistance of the globe : the resistance in theory :: 0.2321 : 0.1598 X 1.115 :: 0.2321 : 0.1782, which is nearly in the ratio of 4 : 3. Thus far we have considered the resistance of bodies moving in a fluid ; we come next to consider the action of a fluid in motion on a body at rest. A vessel 5 feet high was filled with a fluid, which could be discharged by a stop- cock, in a direction parallel to the horizon. The cock being opened, the curve which the stream described was marked out on a plane set perpendicular to the horizon; and, by examining this curve, it was found to be a very accurate parabola, the abscissa of which was 13.85 inc. and the ordinate was 50 inc.; hence the latus rectum was 180.5 inc. ± of which is 45.1 inc. which is the space through which a body must fall to acquire the velocity of projection; hence that velocity was I89.6 inc. in a second. And here, by the bye, we may take notice of a remarkable cir- cumstance. The depth of the cock below the surface of the fluid was 45.1 inc.; hence the velocity of projection was that which a body acquires in falling through a space equal to the whole depth of the fluid ; whereas, through a simple orifice, the velocity would have been that which is acquired in falling through half the depth; the pipe of the stop-cock therefore increased the velocity of the fluid in the ratio of 1 : V 1, and gave it the greatest velocity possible; the length of the pipe was 3 inc. and the area of the section 0.045 inc.; also, the base of the vessel was a square, the side of which was 12 inches. The area of the section of the pipe may be found very accurately, in the follow- ing manner. The vessel being kept constantly full, receive the quantity of fluid run out in any time t", and then weigh it, by which we shall be able to get the quantity in cubic inches. Now if v = the velocity of the fluid when it issues from the pipe, a = the area of the section of the pipe, / = the length of the cylinder of water run out, wbose base = a, and m = the quantity of fluid discharged in t!,\ then v : I :: 1J : t", hence, / = vt\ but al = m; therefore avt = m; hence a = ™. In the present instance, t = 20, m = 1 70.63 cubic inches, v = I89.6; hence a = 0.045. Let abcd, fig. 1, pi. 5, be a solid piece of wood, on which are fixed 2 upright pieces, rs} tu; between these, a flat lever eac is suspended, in a perpendicular posi- tion, on the axis xy, and nicely balanced; and let a be a point directly against the middle of the axis, in a line perpendicular to the plane of the lever. This apparatus is placed against the stop-cock, at the distance of about 1 inch, and, when the water is let go, let us suppose the centre of the stream to strike the lever perpen- dicularly at F.R.S. p. 103. As the investigation of the resources of nature in the animal economy, for the maintenance of health, and the prevention of disease, cannot but be interesting to the philosopher as well as to the physician, I am therefore induced to submit to the e. s. the following observations. There is a remarkable contrivance in the blood vessels which supply the heart, not to be met with in any other part of the body, and which is of great use in the healthy functions of that organ, but which is par- ticularly serviceable in preventing disease of a part so essential to life. A distended state of the blood vessels must always impede their functions, and consequently be very detrimental to the health of the part which they supply; but as the cavities of the heart are naturally receptacles of blood, a singular opportunity is afforded to its nutrient vessels, to relieve themselves when surcharged, by pouring a part of their contents into those cavities. Such appears to be the use of the foramina by which injections, thrown into the blood vessels of the heart, escape into the cavities of that organ; and which were first noticed by Vieussens, but, being more expressly described by Thebesius, generally bear the name of the latter author. Anatomists appear to have been much perplexed concerning these foramina The- besii; even Haller, Senac, and Zinn, were sometimes unable to discover them; which suggested an idea, that when an injection was effused into the cavities of the heart, the vessels were torn, and that it did not escape through natural openings. When these foramina were injected, they were found under various circumstances, as to their size and situation ; and Haller observed, that the injection, for the most part, escaped into the right cavities of the heart. It also remains undetermined, whether these foramina belong both to the arteries and veins, or respectively to- each set of vessels. It is from an examination of these openings in diseased subjects, that a solution of such difficulties may probably be obtained. Whoever reflects on the circum- stances under which the principal coronary vein terminates in the right auricle of the heart, will perceive that an impediment to the flow of blood through that vessel 288 PHILOSOPHICAL TRANSACTIONS. [ANNO 1798. must occasionally take place; but the difficulty will be much increased, when the right side of the heart is more than ordinarily distended, in consequence of obstruc- tion to the pulmonary circulation. Indeed it seems probable that such an obstruc- tion, by occasioning a distended state of the right side of the heart, and thus im- peding the circulation in the nutrient vessels of that organ, would as necessarily occasion corresponding disease in it, as an obstruction to the circulation in the liver occasions disease in the other abdominal viscera, were it not for some preventing circumstances, which I now proceed to explain. Having been attentive to some very bad cases of pulmonary consumption, from a desire to witness the effects of breathing medicated air in that complaint, I was led to a more particular examination of the heart of those patients who died. In these cases, I found, that by throwing common coarse waxen injection into the arteries and veins of the heart, it readily flowed into the cavities of that organ; and that the left ventricle was injected in the first place, and most completely. When the ventricle was opened, and the effused injection removed, the foramina Thebesii appeared both numerous and large, and distended with the different co- loured wax which had been impelled into the coronary arteries and veins. On 8 comparative trials, made by injecting the vessels of hearts taken from subjects whose lungs were either much diseased, or in a perfectly sound state; I found, that in the former, common injection readily flowed, in the manner which I have described, into all the cavities of the heart, but principally into the left ventricle; while, in many of the latter, I could not impel the least quantity of such coarse injection into that cavity. This difference in the facility with which the cavities of the heart can be injected from its nutrient vessels, was observed by most anatomists, though they did not advert to the circumstances on which it depended. Haller's recital of his own ob- servations, and of those of others on this subject, so well explain the facts which I have stated, that I shall take the liberty of quoting the passage, in order further to illustrate and authenticate them. He says, " Si per arterias liquorem injeceris, perinde in dextra auricala, sinuque et ventriculo dextro, et in sinu atque thalamo sinistro guttulae exstillabunt; saepe quidem absque mora, alias difficilius, et non- nunquam omnino, uti continuo dicemus, et mihi, et Senaco, et clarissimo Zinnio, nihil exsudavit." — Elem. Physiol. Tom. 1, p. 382. As it seems right that the blood which had been distributed by the corouary arteries, and which must have lost, in a greater or less degree, the properties of arterial blood, should not be mixed with the arterial blood which is to be distributed to every part of the body, but ought rather to be sent again to the lungs, in order that it may re-acquire those properties; we therefore perceive why, in a natural state of the heart, the principal foramina Thebesii are to be found in the right cavities of that organ. However, as, even in a state of health, those cavities are liable to be uncommonly distended, in consequence of muscular exertion sometimes forcing the venous blood into the heart faster than it can be'transmitted through the lungs, ▼OL. LXXXVII1.] PHILOSOPHICAL TRANSACTIONS. 289 there seems to arise a necessity for similar openings on the left side; but these, in their natural state, though capable of emitting blood, and of relieving the plethora of the coronary vessels, are not of sufficient size to give passage to common waxen injections. Yet, when there is a distended state of the right cavities of the heart, which is almost certainly occasioned by a diseased state of the lungs, these fora- mina leading into the left cavities then become enlarged, in the manner that has been already described; and thus the plethoric state of the nutrient vessels of the heart, and the consequent disease of that important organ, are prevented. The preceding remarks will, I think, sufficiently explain the cause of the variety in the size and situation of these foramina, which also appear to belong both to the arteries and veins; because the injection which was employed was too coarse to pass from one set of vessels to the other, and yet the different coloured injections passed into the cavities of the heart unmixed. There is vet another mode by which diseases of the heart, that would otherwise so inevitably succeed to obstruction in the pulmonary vessels, are avoided; and which I next beg leave to explain. Having formerly been much surprized to find the heart so little affected, when the lungs were greatly diseased, and observing, in one or two instances, that the foramen ovale was open, I was led to pay more par- ticular attention to the state of that part; and I have found this to be almost a con- stant occurrence in those subjects where pulmonary consumption had for some time existed previous to the person's decease. I took notice of this circumstance 13 times in the course of one year; and in several instances the aperture was suffi- ciently large to admit of a finger being passed through it. Now, as the septum auricularum is almost constantly perfect in subjects whose lungs are healthy, I can- not but conclude, that the renewal of the foramen ovale is the effect of disease; nor will the opinion appear on reflection improbable; for the opening becomes closed by the membranous fold growing from one edge of it, till it overlaps the other, and their smooth surfaces being kept in close contact, by the pressure of the blood in the left auricle, they gradually grow together. But, should there be a deficiency of blood in the left auricle, and a redundance in the right, the pressure of the latter on this membranous partition, will so stretch and irritate the uniting medium, as to occasion its removal; and thus a renewal of the communication be- tween the auricles will again take place. From these observations it is natural to suppose, that in those men, or animals, who are accustomed to remain long under water, this opening will either be main- tained or renewed; yet on this circumstance alone the continuance of their life does not depend; for we now have sufficient proof, that if the blood is not oxygenated in the lungs, it is unfit to support the animal powers. There is an experiment related by Buffon, the truth of which I believe has not been publicly controverted, and which tends greatly to misrepresent this subject. He says, that he caused a bitch to bring forth her puppies under warm water; that he suddenly removed them into a pail of warm milk; that he kept them immersed in the milk for more than vol. xviii . P p 1Q0 PHILOSOPHICAL TRANSACTIONS. [ANNO 17Q8. half an hour; and that when they were taken out of it, all the 3 were alive. He then allowed them to respire ahout half an hour, and again immersed them in the warm milk, where they remained another half hour; and when taken out 2 were vigorous, but the 3d seemed to languish: this submersion was again repeated, with- out apparent injury to the animals. This experiment is so directly contrary to what we are led to believe from all others, and also to the information derived from cases which frequently occur in the practice of midwifery, in which an interruption to the circulation through the umbilical chord occasions the death of the foetus, as to make me suspect its truth: I was therefore induced to examine what would happen in a similar experiment. I did not indeed cause the bitch to bring forth her puppies in water; but immersed a puppy, shortly after its birth, under water which was of the animal temperature. It lost all power of supporting itself in about 60 seconds^ and would shortly have perished, had I not removed it into the air. Neither could I, by repeating this experiment, so accustom the animal to the circulation of unoxygenated blood, as to lengthen the term of its existence in such an unnatural situation. I thought that a dog might have been made a good diver in this way; but having satisfied myself that this could not be done, without greatly torturing the animal, I did not choose to prosecute so cruel. an experiment. Young animals, indeed,, retain their irritability for a considerable time, so that they move long after they have been plunged beneath water; and may even, on this account, recover after they are taken out. But the manner in which Buffon has related his experiment seems to imply; that the circulation of the blood, and other functions of life, were continued after the animals had been excluded from the air. I am convinced that the poor dog which was the subject of my experiment would have been beyond recovery in a few minutes. Those animals which are accustomed to remain long under water, probably first fill their lungs with air, which may, in a partial manner, oxygenate their blood during their submersion. The true state- ment of this subject may probably be, that the circulation of venous blood will de- stroy most animals in a very short space of time; but that custom may enable others to endure it, with very little change, for a longer period. VI. Analysis of the Earthy Substance from New South Wales, called Sydneia or Terra Australis. By Charles Hatchett, Esq., F.R.S. p. 110. $ 1. The late ingenious Josiah Wedgwood, Esq., f.r.s., published, in the Phil. Trans, for 1790, an account of some analytical experiments on a mineral substance from Sydney Cove, in New South Wales. This substance he describes as com- posed of a fine white sand, a soft white earth, some colourless micaceous particles, and also some which were black, resembling black mica, or black lead. Nitric acid did not appear to act on any part of this earthy substance ; and even a portion on which sulphuric acid had been boiled to dryness, afforded afterwards, when edulco- rated with water, only a few flocculi, which Mr. Wedgwood conceived to be alu- VOL. LXXXVIII.] PHILOSOPHICAL TRANSACTIONS. 2Q1 minous earth. The muriatic acid, during digestion, seemed to act as little as the 2 preceding acids; but on water being poured in, to wash out the remaining por- tion, the liquor instantly became white as milk, with a fine white curdy substance intermixed; the concentrated acid having, in the opinion of the author, extracted something which the simple dilution with water precipitated. The remaining part was repeatedly digested with muriatic acid, and treated with water, as before, till the milky appearance was no longer produced. The properties of this white precipitate, Mr. Wedgwood states to be as follows. 1°. It is only soluble in boiling concentrated muriatic acid. 2°. It is precipitated by water, in the form of a white earth; which may again be dissolved by boiling muriatic acid. 3°. When nitric acid is mixed with the muriatic solution of this earth, there is no appearance of a precipitate; not even when water is added, pro- vided the nitric acid exceeds, or nearly approaches, the quantity of muriatic acid. 4°. The earth is precipitated by the alkalies. 5°. The muriatic solution does not crystallize by evaporation; but becomes a butyraceous mass, which soon liquefies on exposure to the air. 6°. The butyraceous mass is not corrosive to the taste; and is even less pungent than the combination of calcareous earth with the same acid. 7°. Heat approaching to ignition disengages the acid from the butyraceous mass, in white fumes, and a white substance remains. 8°. The white precipitated earth is fusible per se, in from 142° to 156° of Mr. Wedgwood's thermometer, and it is thus distinguished from all the other primitive earths. And, 90. This preci- pitate cannot be reduced to a metallic state, when exposed to heat with inflammable substances. From these properties, Mr. Wedgwood says, that though he cannot absolutely determine whether this substance belongs to the class of earths, or that of metallic substances, yet he is inclined to refer it to the former. Professor Blumenbach, of Gottingen, in his Manual of Natural History, published in 1791, also mentions that he had examined a portion of this earthy substance, by means of muriatic acid, after the manner of Mr. Wedgwood, and that he had obtained a slight precipitate by the addition of water. In consequence of these experiments, the mineralogists throughout Europe admitted the white precipitated substance to be a primitive earth; and we accordingly find, in all the systematical works on mineralogy published since the above-mentioned period, that it is arranged as a distinct genus, under the names of Sydneia, Australa, Terra Australis, and Austral Sand. The extreme scarcity of this substance prevented the chemists in general from examining more minutely into the nature of this new primitive earth, till Mr. Klaproth, in the 2d volume of his Additions to the Chemical Knowledge of Mineral Bodies, gave to the public a memoir entitled, A Chemical Examination of the Austral Sand. In this memoir, Mr. Klaproth says, that he had received from Mr. Haidinger, of Vienna, 2 samples of this substance; one of which had a consi- derable quantity of black shining particles intermixed with it, which, though regarded by many as graphite or plumbago, he was inclined to believe to be eisen- p p 2 292 PHILOSOPHICAL TRANSACTIONS. [ANNO J 798. glimmer or micaceous iron ore. The other contained much less of these black or dark grey particles, and, as he considered it to be more pure than the former he subjected it to the following experiments. 1. It was digested at 3 different times with concentrated muriatic acid, in a boiling heat, and the acid was afterwards fil- trated through paper. The solution was then mixed by degrees with pure water, which did not however produce any precipitate, even when warmed. Carbonate of pot-ash caused some flocculi to fall, which, edulcorated and dried, weighed 3.25 grs. This precipitate was dissolved in diluted sulphuric acid, and left a small portion of siliceous earth; after which the solution, by evaporation, afforded crystals of alum. 2. The residuum of the muriatic solution was mixed with 3 times the weight of pot-ash, and exposed to a red heat. Muriatic acid was then poured on the mass, and the insoluble gelatinous residuum was edulcorated on a filter; and, after a red heat, weighed 19.50 grs., which proved to be siliceous earth. 3. The muriatic so- lution, with prussiate of pot-ash, afforded a blue precipitate; the ferruginous part of which was about 4- gr. 4. The solution was then saturated with carbonate of pot-ash, and some alumine was precipitated; which, after a red heat, weighed 8.50 grs., and with sulphuric acid formed alum. Siliceous earth, alumina, and iron, appeared therefore to be the only ingredients of this substance; but, as Mr. Klaproth had no more than 30 grs. to examine, he could not extend his experi- ments. From those above related, he is of opinion that the existence of this primitive earth may be much doubted, and that this doubt can only be removed in the course of time, by other analyses. Mr. Klaproth concludes his memoir by saying, that the substance examined by him was undoubtedly the genuine austral sand, as Mr. Haidinger had received it from Sir Jos. Banks, when he was in London. Mr. Nicholson however, in the 9th N° of his Journal of Nat. Philos. &c. p. 410, published on the 1st of Dec. 1797> questions much, whether the substance exa- mined by Mr. Klaproth was the same as that examined by Mr. Wedgwood; and, after having contrasted their experiments, says, " hence it seems fair to conclude that the 2 minerals were not the same, however this may have happened; and that the existence of the new fusible earth of Wedgwood stands on the same evidence as before, namely, his experiments, which have not yet been repeated, that I know of." Some of Mr. Nicholson's objections to the experiments of Mr. Klaproth, being founded principally on some difference in the external characters of the sub- stance examined by him, and the one examined by Mr. Wedgwood, are such as very naturally occur; but the following pages will I believe prove, that Mr. Klap- roth's experiments were made on that which might be justly regarded as the Sydneia or austral sand. In 1796, Sir Jos. Banks, p. b. s. favoured me with a specimen of the Sydneia, which has been lately brought to England; a portion of this I soon after examined, in a cursory manner, by muriatic acid, but did not obtain any precipitate when water was added to the nitrated solution. On mentioning this circumstance, and VOL. LXXXVIII.J PHILOSOPHICAL TRANSACTIONS. 1Q3 expressing a desire to examine this substance with more accuracy, Sir Jos. Banks, not only permitted me to take specimens from different parts of the box which contained the earth already mentioned, but that every doubt might be obviated, gave me about 300 grs. which remained of the identical substance examined by Mr. Wedgwood. On these the following experiments were made ; and, to distinguish them, I shall call the first, N° 1, and that examined by Mr. Wedgwood, N° 2. § 2. Analysis of the Sydneia, N° 1. — The Sydneia, N° I, is in masses and lumps, of a pale greyish white, intermixed with a few particles of white mica, and also occasionally with some which are of a dark grey, resembling graphite or plumbago. Jt easily crumbles between the fingers, to a powder nearly impalpable, which has rather an unctuous feel. Small fragments of vegetable matter are also commonly found intermixed with it; and the general aspect is that of an earthy substance which has been deposited by water. Exper. 1 . 400 grs. were put into a glass matrass, and 1 quart of distilled water being added, the whole was boiled to 4-th. The liquor was then filtrated, and a portion being examined by the re-agents commonly used, afforded no trace of matter in solution. The remainder was then evaporated, without leaving any re- siduum. Eocper. 2. About 200 grs. of the earth, rubbed to a fine powder, were put into a glass retort, into which I poured 3 oz. of concentrated pure muriatic acid. The retort was placed in sand, and the acid was distilled, till the matter in the retort remained dry. 2 oz. of muriatic acid were again poured on it, and distilled as before, till -f remained. The whole was then put into a matrass, which was placed in an inclined position, so that when the earth had subsided, the liquor might be decanted, without disturbing the sediment. When it had remained thus for 12 hours, the acid was carefully poured into a glass vessel; but, as I observed that it was not so perfectly transparent as before it had been thus employed, I suf- fered it to remain 24 hours, but did not perceive any sediment. Half of this liquor was diluted with about 12 parts of distilled water, and after a few hours a very small quantity of a white earth subsided. This however did not appear to be a precipitate caused by a change in the chemical affinities, but rather an earthy matter which had been suspended in the concentrated acid, and afterwards de- posited, when the liquor was rendered less dense by the addition of water. To ascertain this, I poured the remaining portion of the concentrated liquor on a filter of 4 folds: it passed perfectly transparent, and, though diluted with 24 parts of water, it remained unchanged, and as pellucid as before. I now filtrated the former portion, and added it to that already mentioned, It was then evaporated to dryness, and left a pale brownish mass, which was dis- solved again, by digestion, in the smallest possible quantity of muriacic acid. Water was added, in a very large proportion, to this solution, without producing any effect; I then, by prussiate of pot-ash, precipitated a quantity of iron, which was separated by a filter. The clear solution was then saturated with lixivium of 1QA PHILOSOPHICAL TRANSACTIONS. [ANNO 17 98. carbonate of pot-ash, and a white precipitate was produced, which was collected and edulcorated. This, when digested with diluted sulphuric acid, was dissolved; and the superfluous acid being driven off by heat, boiling water was poured on the residuum, which completely dissolved it. To this solution some drops of lixivium of pot-ash were added, and by repeated evaporations the whole formed crystals of alum. From the above experiment it appeared, that the muriatic acid had only dissolved some alumina and iron ; but, in order to satisfy myself more completely in respect to the component parts of this substance, I made the following analysis. Analysis. — A. 400 grs. were put into a glass retort, which was then made red-hot during half an hour. Some water came over, and the earth afterwards weighed 380.80 grs., so that the loss amounted to 1 9.20 grs. The greater part of this loss was occasioned by the dissipation of the water imbibed by the earth; to which must be added, the loss of weight caused by the combustion of a small portion of vegetable matter. b. The 380.80 grs. were rubbed to a fine powder, and being put into a glass retort, 1470 grs. of pure concentrated sulphuric acid were added. The retort was then placed in a small reverberatory, and the fire was gradually increased, till the acid was distilled over: it was then poured back on the matter in the retort, and distilled as before, till a mass nearly dry remained. On this, boiling distilled water was repeatedly poured, till it no longer changed the colour of litmus paper, and was devoid of taste. The undissolved portion was then dried, and made red-hot; after which it weighed 28 1 grs. c. I now mixed the 281 grs. with 300 grs. of dry carbonate of pot-ash, and ex- posed the mixture to a strong read heat, in a silver crucible, during 4 hours. The mass was loose, and of a greyish white: it was softened with water, and being put into a retort, sulphuric acid was added to a considerable excess. The whole was then distilled to dryness, and when a sufficient quantity of boiling water had been added, it was poured on a filter, and the residuum was well washed; it was then made red-hot, and afterwards weighed 274.75 grs. d. The solutions of b and c were added together, and were much reduced by evaporation. Pure ammonia was then employed to saturate the acid, and a copious loose precipitate, of a pale yellowish colour, was produced; which, collected, edul- corated, and made red-hot, weighed 103.70 grs. — e. The filtrated liquor of d was again evaporated, and carbonate of pot-ash being added, a slight precipitation of earthy matter took place; which, by the test of sulphuric acid proved to be some alumina which had not been precipitated in the former experiment: this weighed 1.20 grs. — f. The 103.70 grs. of d were completely dissolved when digested with nitric acid, excepting a small residuum of siliceous earth, which weighed O.gOgrs. — g. The nitric solution was evaporated to dryness, and a 2d portion of the same acid was added, and in like manner evaporated. The residuum was then made red-hot, and digested with diluted nitric acid, which left a considerable portion of red oxide of iron. The solution was again evaporated, and the residuum, being treated as VOL. LXXXVIII.] PHILOSOPHICAL TRANSACTIONS. 2Q5 before, again deposited some oxide of iron, much less in quantity than the former. The whole of the oxide was then heated with wax in a porcelain crucible, was taken up by a magnet, and weighed 26.50 grs. # h. The nitric solution of g was saturated with ammonia, and a loose white pre- cipitate was formed; which edulcorated and made red-hot, weighed 76 grs. — 1. These 76 grs. were dissolved when digested with diluted sulphuric acid; and, when the excess of acid had been expelled by heat, the saline mass was dissolved in boiling water. To this solution I added some lixivium of pot-ash, and by gradual and repeated evaporations, obtained the whole in regular octoedral crystals of alum. k. The 274.75 grs. of c now alone remained to be examined. They appeared to consist of siliceous earth, mixed with the dark grey shining particles already mentioned; but, as I shall describe, in the following experiments, the process by which these were separated, I shall now only say that they amounted to 7.50 grs. — l. The earth with which the above-mentioned particles were mixed weighed 267-25 grs. This Grains, earth was white, and arid to the touch: when Pure siliceous earth or silica / £' ggSgJ melted with 2 parts of soda, it formed a colour- Alumina /E* 1,2° less glass ; and with 4 parts of the same it dis- Qxide of iron _"" '. \ ' \ «■ £ 72f50 solved in water, and formed a liquor silicum ; it Dark grey particles k. 7.50 was therefore pure siliceous earth or silica. The Water and ve§etable matter A- WM substance here examined was composed there- 358.55 fore of the following ingredients. The foregoing analysis was repeated several times, and always with similar results; excepting, that as I had taken the specimens from different parts of a large quan- tity, I found that the proportions of the ingredients were not constantly the same: that of the siliceous earth, for example, was sometimes greater, and the alumina and iron proportion ably less. Some specimens were also nearly or totally destitute of the dark grey shining particles; in short, every circumstance was such as might be expected from a mixed substance, which, from the nature of its formation, cannot have the ingredients in any fixed proportion*. As this substance agreed in its general characters, for the greater part, with that described by Mr. Wedgwood, and as it was indisputably brought from the same place, there appeared every reason to believe that the nature of both was the same; but, to obviate as much as pos- sible any doubt or objection, I determined to repeat the experiments, and the analysis, on that portion which remained of the identical substance examined by Mr. Wedgwood, and which from that period had been reserved by Sir Jos. Banks. § 3. Analysis of the Sydneia, N° 2. — This substance, then consists of a white * The description given by Mr. Klaproth convinces me, that his experiments were made on a portion of this substance. Also, when Mr. Haidinger was in London, I gave him some of this earth for his collection j so that, whether Mr. Klaproth made his experiments on that which had been received by Mr. Haidinger from Sir Jos. Banks, or from myself, it is not less certain that he operated on that which might be regarded as the genuine Sydneia. — Orig. 296 philosophical transactions. [anno 1798. transparent quartzose sand, a soft opaque white earth, some particles of white mica, and a quantity of dark lead-grey particles, which have a metallic lustre. The Sydneia, N°2, appears chiefly to differ from N° 1, by being more arenaceous, and by a larger proportion of the dark grey particles. Many experiments, similar to those made on N° 1, already described, were made on this substance, with pure concentrated muriatic acid ; but as none of these afforded any appearance of a pre- cipitate by the means of water, I do not think it necessary to enter into a circum- stantial account of them, and shall proceed therefore to the analysis. a. 100 grs. were exposed to a red heat, in a glass retort, and, after 4- an hour, were found to have lost in weight 2.20 grs. — b. The 97-80 grs. which remained were mixed with 300 grs. of dry carbonate of pot-ash, and the mixture was exposed to a strong red heat, in a crucible of silver, during 3 hours. When cold, the mass was softened with water, and was put into a glass matrass. I then added 3 oz. of pure concentrated muriatic acid, and digested it for 2 hours in a strong sand heat. Boiling water was then added, and the whole being poured on a filter, the residuum was edulcorated, dried, and made red-hot ; it then weighed 85. bO grs. — c. The filtrated solution was evaporated to -f, and pure ammonia being added, a precipitate was formed, which, after a red heat, weighed 10.70 grs. — d. 1 oz. of muriatic acid was poured on the IO.70 grs., in a matrass, which was then heated. The whole of the 10.70 grs. was dissolved, excepting a small portion of siliceous earth, which weighed 0.30 gr. e. The muriatic solution was then reduced by evaporation, to about ± ; to which was added a large quantity of distilled water, which did not however produce any change. I then gradually added a solution of pure crystallized prussiate of pot-ash, and heated the liquor till the whole of the iron was precipitated ; after which, am- monia precipitated a loose white earth, which, edulcorated and made red-hot, weighed 7. 20 grs. The iron precipitated by the prussiate may therefore be esti- mated at 3.20 grs. — f. The 7.20 grs. of the white earth were digested with sulphuric acid, and, after the excess of acid had been expelled by heat, boiling water was poured on the saline residuum. The solution was then gradually evaporated, with the addition of a small portion of lixivium of potash, and afforded crystals of alum, without a trace of any other substance. g. I now proceeded to examine the 85.50 grs. of b. These appeared to con- . sist of siliceous earth, or fine particles of quartz, mingled with a considerable quan- tity of the dark grey shining particles. Mr. Wedgwood was of opinion that these were a peculiar species of plumbago or graphite. Professor Blumenbach, on the contrary, regards them as molybdaena : and Mr. Klaproth believes them to be eisenglimmer or micaceous iron ore. When rubbed between the fingers, they leave a dark grey stain, and the feel is unctuous, like that of plumbago, or mo- lybdaena : the traces which they make on paper also resemble those of the above- mentioned substances, but the lustre of the particles approaches nearer to that of molybdaena. VOL. LXXXVIII.] PHILOSOPHICAL TRANSACTIONS. 20,7 In order therefore to determine whether they consisted totally or partially of molybdaena, I put the 85.50 grs. into a small glass retort, and added 2 oz. of con- centrated nitric acid. The retort was then placed in a sand heat, and the distilla- tion was continued, till the matter remained dry. The acid was then poured back into the retort, and distilled as before ; but I did not observe that the grey particles had suffered any change, nor were nitrous fumes produced, as when molybdaena is thus treated. To be more certain however, I digested pure ammonia on the resi- duum ; and having decanted it into a matrass, I evaporated it to dryness, without perceiving any vestige of oxide of molybdaena, or indeed of any other substance. It was evident therefore that molybdaena was not present ; and as the general external characters and properties corresponded with those of plumbago, I was in- clined to believe that these were particles of that substance, and not micaceous iron, as Mr. Klaproth imagined. To determine this, the following experiment was made. h. 200 grs. of pure nitre in powder were mixed with the 85.50 grs., and the mixture was gradually projected into a crucible, made strongly red-hot. A feeble detonation took place at each projection; and, after a 4- hour had elapsed, the crucible was removed. When cold, the mass was porous and white, without any appearance of the dark grey particles. Boiling water was poured on it, and the whole being put into a matrass, 1 oz. of muriatic acid was added, and digested with it in a sand heat. By evaporation it became gelatinous : it was then emptied on a filter, and being well washed, dried, and made red-hot, weighed 75.25 grs. The appearance of this was that of a white earth, arid to the touch. When melted with 2 parts of soda, a colourless glass was formed; and, with 4 parts of the same, it was soluble in water, and produced liquor silicum ; it was therefore pure siliceous earth. i. The filtrated liquor was saturated with ammonia, and, on being heated, a few brownish flocculi were precipitated, which, when collected and dried, weighed 0.40 grs. This precipitate was dissolved in muriatic acid, and was again precipitated by prussiate of pot-ash, in the state of Prussian blue. The liquor from which the flocculi of iron had been separated was then examined, by adding carbonate of pot- ash, and lastly, by being evaporated to dryness ; but it no longer afforded any earthy or metallic substance : so that, by the process of detonation with nitre, the 85.50 grs. afforded 75.25 grs. of pure siliceous earth, with 0.40 gr. of iron ; and, as the dark grey substance was destroyed, excepting the 0.40 gr. of iron above- mentioned, and as Q.85 gr. of the original weight of 85.50 gr. were dissipated, there can be no doubt but that this substance, amounting to 1 0.25 grs., was car- buret of iron or plumbago ; especially as some experiments which I purposely made, on that from Keswick in Cumberland, were attended with similar results. It is also evident, that these particles could not be eisenglimmer or micaceous iron, as nitre has little or no effect on that substance, when projected into a heated crucible. VOL. XVIII. Q Q 1Q8 PHILOSOPHICAL TRANSACTIONS. [ANNO 1798. In a subsequent experiment on the same, the crucible was removed immediately after the last projection, and I then observed that an effervescence, with a disen- gagement of carbonic acid, took place, on the addition of the muriatic acid, as is usual when pure plumbago is decomposed by nitre, and that less of the gelatinous matter was formed by evaporation. The cause of this difference was evidently the duration of the red heat ; for in the first instance the alkali developed by the de- composition of the nitre had time to unite with the siliceous earth, so as, when dis- solved, to form liquor silicum ; but in the 2d ex- * [ Grains. periment a portion of alkali remained combined ^ r d. 0.30 with the carbonic acid, produced by the carbon of Alurmna "' p^o the decomposed plumbago. The produce of 100 Oxide of iron e. 3.20 grs. by this analysis was as annexed. Mr. Wedg- Graphite or plumbago ... u 10.25 wood says, that sulphuric acid cannot dissolve the precipitated earth, and has but little effect on the ^8.40 mixed substance, even when distilled to dryness ; but, from the preceding experi- ments, I had reason to believe that the aluminous earth and iron would be sepa- rated by reiterated distillation ; I therefore repeated the analysis in the following manner. Second analysis of the Sydneia, N° 2. — A. 100 grs. of the earth were put into a glass retort, on which 400 grs. of pure concentrated sulphuric acid were poured. The retort was placed in a small reverberatory, and the fire was continued till a dry mass remained. 400 grs. of the acid were again poured in, and distilled as before. On the dry mass, boiling water was poured, and the whole was then emptied on a filter, and edulcorated. The residuum, after a red heat, weighed 87*75 grs., and consisted of siliceous earth, mixed with some mica, and with particles of plumbago. b. The filtrated solution, by ammonia, afforded a precipitate, which weighed g.50 grs. ; and, being examined, as in the former experiment, yielded 6.50 grs. of alumina, and 3 errs, of oxide of iron. The plum- . . 1 1 •!• • Grains. bago was separated from the siliceous matter, in Silica and mica 77. .75 the manner already described, and amounted to ^mm^*. „ ° * \ t Oxide or iron ., . . 3 about 1 0 grs. By this analysis I obtained as an- Plumbago 10 nexed: it appears therefore that the Sydneian earth, "07T5 when treated with sulphuric acid, is capable of being for the greater part decomposed ; and Mr. Wedgwood probably did not suc- ceed, because his process was in some respect different, or that the distillation was not sufficiently repeated. I have not thought it necessary to be more circumstantial in the account of this 2d analysis, as the operations were similar to those of the former. § 4. These experiments prove, that the earthy substance called Sydneia or terra australis, consists of siliceous earth, alumina, oxide of iron, and black lead or graphite. The presence of the latter appears to be accidental, and it probably was VOL. LXXXVIII.] PHILOSOPHICAL TRANSACTIONS. 299 mixed with the other substances at the time when they were transported, and de- posited, by means of water ; for this appears evidently to have been the case, from the general characters of this mixed earthy substance. The quartz and mica, which are so visible, indicate a granitic origin ; and the soft white earth has probably been formed by a decomposition of feldt spar, such as is to be seen in many places, and particularly at St. Stephen's, in Cornwall. The granitic sand which covers the borders of the Mer de Glace, at Chamouni, in Savoy, also much resembles the terra australis, excepting that the feldt spar is not in a state of decomposition : in short, the general aspect, and the analysis, concur to prove, that the Sydneia has been formed by the disintegration and decomposition of granite, or gneiss. My. Wedgwood's experiments are so circumstantial, that had I only examined the earth last brought to England, I should have supposed, with Mr. Nicholson, that I had operated on a different substance ; but, as I had an opportunity to exa- mine, by analysis, a portion of the same earth on which Mr. Wedgwood made his experiments, and as I received it from Sir Jos. Banks, the same gentleman who had furnished Mr. Wedgwood with it, no suspicion can be entertained about. its identity. Some of the experiments which I have related, and which prove that some of the finer earthy particles remained suspended in the concentrated muriatic acid, and were precipitated when the acid was diluted with water, appear in some measure to account for the mistake which has been made, in supposing that a primitive earth, before unknown, was present ; but this alone will not account for many of the other properties mentioned by Mr. Wedgwood, such as, 1st. The repeated and exclusive solubility in the muriatic acid, and subsequent precipitation by water. 2d. The butyraceous mass which was formed by evaporation. And, 3dly. The degree of fusibility of the precipitated earth. These indeed I can by no means explain, but by supposing that the acids used by Mr. Wedgwood were impure. This supposi- tion appears to be corroborated by a passage in Mr. Wedgwood's paper, where he says, " here the Prussian lixivium, in whatever quantity it was added, occasioned no precipitation at all, only the usual bluishness arising from the iron always found in the common acids." Now if, as it seems from this expression, Mr. Wedgwood employed the common acids of the shops, without having previously examined and purified them, all certainty of analysis must fall, as the impurity of such acids is well known to every practical chemist : but, whether this was the cause of the effects described by Mr. Wedgwood, I do not hesitate to assert, that the mineral which has been examined does not contain any primitive earth, or substance pos- sessing the properties ascribed to it, and consequently, that the Sydneian genus, in future, must be omitted in the mineral system. q a 2 300 PHILOSOPHICAL TRANSACTIONS. [anno 1798. VII. Abstract of a Register of the Barometer, Thermometer, and Rain, at Lyndon, in Rutland, for 1796. By Thes. Barker, Esq. p. 130. Barometer Thermometer. 1 Rain. In the House. Abroad. Highest. Lowest. Mean. Hig. Low Mean Hig. Low Mean Inches. Inches. Inches. O 0 O O , o Inch. Jan. Morn. Aftern. 29.77 28.47 29.1? 50 52 4r 41$ 45 46 52$ 55 32 34 42$ 47 1.955 Feb. Morn. Aftern. 29.87 28.53 32 45 $ 51 38 34 42 42$ 49, 51$ 31$ 32 38 43 1.643 Mar. Morn. Aftern. 29.97 29.22 57 48 51 33 34 41 42$ 45 57 26 34 36 45 0.376 Apr. Morn. Aftern. 29.88 28.67 59 59 61 44 45 50$ 52 52 72 36 45 45 57% 0.649 May Morn. Aftern. 29-73 28.33 27 55 56 47 48 51 52 52 65 40 48 46 56 2.839 June Morn. Aftern. 29-84 29.05 47 59 70 50% 52 55 57 60 80 46 56 54 67 0.927 July Morn. Aftern. 29.73 28.91 32 67 67h 50 54$ 58$ 60$ 64$ 77 49$ 59 56% 68% 5.646 Aug. Morn. Aftern. 29.95 29-23 60 65% 68} 57 58% 61 63 62$ 77 49 57 56 69 1.120 Sept. Morn. Aftern. 29.83 29.03 50 65 68 53 54 59% 61 63 77 42$ 56 54 66 1.891 Oct. Morn. Aftern. 30.07 28.75 45 55% 56 43$ 44$ 49 50h 59 61$ 29 41 43 51$ 1.320 Nov. Morn. Aftern. 29.86 28.69 36 51% 53 39$ 39 43~ 43$ 52$ 57 26 28$ 38 43 2.048 Dec. Morn. Aftern. 29-98 28.75 31 44$ 46$ 28 29% 34 35 48 49 14$ 25 30 34 1.668 Whol e year. 29-41 50 49 22.082 VIII. Of some Endeavours to Ascertain a Standard of Weight and Measure. By Sir G. Shuckburgh Evelyn, Bart. F.R.S. and A. S. p. 133. Having for some years turned my thoughts to the consideration of an invariable and imperishable standard of weight and measure, as a thing, in a philosophical view, highly desirable, and likely to become extremely beneficial to the public, I had, so early as 1780, taken up the idea of a universal measure, whence all the rest might be derived, by means of a pendulum with a moveable centre of suspen- sion, capable of such adjustments, as to be made to vibrate any number of times in a given interval ; and, by comparison of the difference of the vibrations with the difference of the lengths of the pendulum, which difference alone might be the standard measure, to determine its positive length, if that should be thought pre- ferable, under any given circumstances ; by which means, all the difficulties arising in determining the actual centre of motion and of oscillation, which have hitherto so much embarrassed these experiments, would be obviated. I made several computations of the probable accuracy that might be expected from VOL. LXXXVIII.] PHILOSOPHICAL TRANSACTIONS. 301 such an experiment, and was satisfied with their result. But, not seeing clearly how such a pendulum could be connected to a piece of mechanism, to number the vibrations without affecting them, I dropped the idea for that time. I learnt how- ever, some time afterwards, that Mr. John Whitehurst, a very ingenious person, had been in pursuit of the same object with better success, and had contrived a machine fully corresponding to his expectations and my wishes. This he afterwards explained to the world, in a pamphlet, entitled, " An Attempt to obtain Measures of Length, &c. from the Mensuration of Time, or the true Length of Pendulums;'* published in 1787- Mr. Whitehurst having there done all that related to the standard measure of length, and suggested that of weight, it appeared to me that it remained only to verify and complete his experiments. For this purpose, by the assistance of Dr. G. Fordyce, who, at Mr. Whitehurst's death, had purchased his apparatus, I was furnished with the very machine with which Mr. Whitehurst had made his observations. I also procured to be made, by Mr. Troughton, an excellent beam-compass or divided scale, furnished with microscopes and micrometer, for the most exact observations of longitudinal mea- sure: as also a very nice beam or hydrostatic balance, sensible with the -Tl0(i of a grain, when loaded with 61b. Troy at each end. Mr. Arnold made me one of his admirable time-keepers, in order to carry time from my sidereal regulator in my observatory, with which it was adjusted, to the room where I had fixed Mr. White- hurst's pendulum; and who, having taken a journey from London into Warwick- shire, was so good as to assist in the beginning of these experiments. Thus equipped, I went to work in the latter end of Aug. 17 96, when the temperature was about 60°, first to examine the length of the pendulum; when, to my great mortification, I found that the thin wire, of which the rod consisted, was too weak to support the ball in a state of vibration; and that, after 15 or 20 hours action, it repeatedly broke. The same misfortune attended my trials with 3 other different sorts of wires that I had obtained from London. Whether this accident happened from any rust in the old wire, or from want of due temper in the new, or from its being too much pinched between the cheeks, I cannot tell: I can only observe, that all the wires that I used were considerably heavier, and therefore probably stronger, than what Mr. Whitehurst mentions, viz. 3 grains in weight for 80 inches in length; nay, mine proceeded as far as from 5 to 6 grains for that length, and yet I could never get it to support the ball during the whole period of my experiment. This being the case, and being in the country, far removed from the manufactory of this fine wire, I was reluctantly compelled to relinquish this part of the operation to some more favourable opportunity. In the mean while however, I thought it desirable to measure the difference of the lengths of Mr. Whitehurst's pendulum from his own observations; for, very fortunately, the marks that he had made on the brass vertical ruler of his machine were still visible; and this interval, which he calls " 59.892 inches," I determined, on my divided scale made by Troughton, from Mr. Bird's standard, to be = 59.89358 inches, from a mean of 302 PHILOSOPHICAL TRANSACTIONS. [ANNO 1798. 4 different trials in the temperature of 64°; that mean differing from the extremes only by .0003 inch. By this examination, if I have not verified, I have at least preserved, Mr. White- hurst's standard; and, for the present, I shall consider this measure of the difference of the length of the two pendulums, vibrating 42 and 84 times in a minute of mean time, as correct. On this presumption, I shall proceed to the examination of weight. From the opinion of different skilful persons, with whom I have conferred, as well as from the result of my own considerations, I am inclined to believe there is hardly any body in nature, with which we are familiarly acquainted, that is of so simple and homogeneous a quality as pure distilled water, or so fit for the purposes of this inquiry ; and I have concluded, that if the weight of any quantity of water, whose bulk had been previously measured by the above-mentioned scale, could be obtained, under a known pressure* and temperature of the atmosphere, we should be in possession of a general standard of weight. With this view, I directed Mr. Troughton to make, in addition to the very sen- sible hydrostatic balance before-mentioned, a solid cube of brass, whose sides should be 5 inches ; and also a cylinder of the same metal, 4 inches in diameter, and 6 high. From St. Thomas's hospital, by the favour of Dr. Fordyce, I procured 3 gallons of distilled water. With these I made the following observations; but, before I relate the experiments, I will describe the apparatus. Here Sir G. S. adds, the description of his instruments: these were, a beam-compass, or divided scale of equal parts, and a hydrostatic balance. A hollow sphere of brass, of 6 inches diameter, was also provided. Sir G. gives a minute detail of the curious experi- ments and observations he made to ascertain the exact figures, measures, dimen- sions, weights, and specific gravities of all these bodies; the results of all of these being as follow : Of the brass cube, he measured very nicely the length of all the ] 2 linear edges; viz. as it stood on one end as a base, all the 4 linear sides of the top, all those of the bottom, and all the 4 upright edges: the medium of the first 4 was 4.98882; of the 2d, 4.g8955; and of the 3d, 4.98925; all rather below the intended mea- sure, 5 inches. The 3 mean dimensions multiplied all together, gave 124.1 891 7 cubic inches, for the solid content of the cube. In like manner, of the cylinder, the mean of several diameters taken at one end, was 3-99745 inches; at the other end, 3-99785; and the medium of several measures of length was 5.99502; which 3 dimensions multiplied all together, and by the circular factor -7854, gave 74.94823 cubic inches, for the solid content of the cylinder. The diameter of the sphere was, by a medium of many measurements, found to * I do not here mean to infer any opinion respecting the compressibility of water; but only to say, that where water, or any thing else, is weighed in air, the density of that medium, as shown by the barometer and thermometer, must be known, in order to make allowances for it, if necessary. — Orig. PHILOSOPHICAL TRANSACTIONS. 303 VOL. LXXXVIII.] be 6.00745 inches; consequently the cube of this multiplied by .5236, gives 113.5194 cubic inches, for the solid contents of the sphere. Now the results of the several weighings of the cube and cylinder, both in air and distilled water, as contained in the following synopsis. Contents (true to -^§^7) in inches Weight in air, true to 0.02 grain Weight in water, true to 0.10 grain Weight of an equal bulk of water, true ? to 0.12 grain, or lS6]o6s j Weight of a cubic inch of water, from J these experiments j Cube. Therm. Inches. 124.18917 grains. 3^084.82 703.03 6l° 62 60.2 31381.79 252.6'94 Cylinder. 74.94826 21560.05 2553.22 19006.83 253.6C0* Therm. Barom. 62° 62 60.5 Inches. 29.00 29.47 The weight of the sphere in air was 28722.42 grains; and the same in water was 28673.51 grains; this divided by its content, 1 13.5 lg, gives 252.587 grains, for the weight of a cubic inch of distilled water, by Mr. Trough ton's weights ;*j- the barometer being 29.74, and the thermometer 66. Having, through the means of Mr. Whitehurst's observations, and of his own instrument, ascertained the length of his proposed standard, in the latitude of London, 1 1 3 feet above the level of the sea, under a density of the atmosphere corresponding to 30 inches of the barometer, and 60° of the thermometer, which is full as satisfactory, for all practical purposes, as if it had been done in vacuo, which I conceive to be nearly impossible; and having determined the weight of any given bulk of water, compared with this common measure; I believe it now only remains, to ascertain the proportion of this common measure and weight, to the commonly received measures and weights of this kingdom. The difference of the length of the 2 pendulums, from Mr. Whitehurst's observations, appearing to be 59.89358 inches, on Mr. Troughton's scale; and a cubic inch of distilled water in a known state of the atmosphere, having been found to weigh 252.587 Troy grains, according to the weights of the same artist, it remains only to determine the proportions of these weights and measures, to those that have been usually, or * The weight of a cubic inch of common or rain water has been reckoned about 253 grains, some- times = 253.33 grains, at others 253.18. But authors do not seem to have agreed in what they meant by common water, rainwater, pump water, spring water, and distilled water; for occasionally they are all confounded, and made to pass for each other ; and sufficient notice seems not to have been taken of the temperature to which these weights were assigned. — Orig. + But, as will appear hereafter, these weights are too light, when compared with the standard in the House of Commons, by about 1 in 1523.92; the correction therefore, for this difference, would be bs 0.165 grain, to be deducted from 252.587 grains. — .165 And the weight of a cubic inch of distilled water, in grains of the parliamentary > __ „ standard, will be j 304 PHILOSOPHICAL TRANSACTIONS. fANNO 17g8. may be fitly considered as the standards of this kingdom ; and herein a small dis- crepancy between themselves, in these authoritative standards, will have no influ- ence on the general conclusion I propose to draw; which is, not so much to say what has been the standard of Great Britain, as what it shall be henceforward, and may be immutably so; and which shall differ but a very small quantity, and that an assignable one, from those that have been in use for 2 or 300 years past. Bv these means, no inconvenience would be produced from change of terms, or sub- divisions of parts, or from sensible deviation from ancient practice: all that will be done, will be to render that certain and permanent, which has hitherto been fluc- tuating, or liable to fluctuation. To give effect and energy to these suggestions, is the province of another power. The chief standards of longitudinal measure, are those preserved in the Exche- quer; in the House of Commons; at the r. s.; and in the Tower. The first alone indeed bear legal authority, and have been in use for more than 200 years; the last is considered as a copy of them, and is not used for sizing generally. The other two are of modern date ; and though they do not carry with them at present any statuteable authority, yet from the high reputation and acknowledged care of the artists who made them, the celebrated Mr. George Graham, and Mr. John Bird, they are doubtless entitled to very great respect; and are probably derived from a mean result of the comparisons of the old and discordant ones in the Ex- chequer. I shall begin with that of Mr. Graham, which contains also the length of the Tower standard laid down on it ; will proceed then to Mr. Bird's, and finally conclude with those at the Exchequer. May 5, 1797, I went to the apartments of the r. s., at Somerset-House, and made the following observations on Mr. Graham's* brass standard yard, made in 1742. This scale is about 42 inches long, and half an inch wide, containing 3 parallel lines engraven on it, on the exterior and ulterior of which are 3 divisions, expressing feet ; with the letter e at the last division, and, by a memorandum, preserved with it in the archives of the Society, is said to signify English measure, as taken from the standard in the Tower of London. That with the letter f denoting the length of the half of the French toise ; put on here, by the authority and under the inspection of the Royal Academy of Sciences, then subsisting at Paris, to whom it was sent in 1 742, for the purpose of comparing the French and English measures. The middle line, marked Exch. of the three above-mentioned, denotes, as is supposed, the standard yard from the Exchequer. This bar had been previously laid together with my scale divided by Mr. Trough- ton, for 24 hours, to acquire the same temperature; they were also of the same metal, and, by placing it under my microscopes, adjusted to the interval between 10 and 46 inches, I found the interval on the Tower standard exceed mine, by * This rod was not made by Mr. Graham, but, at his instance, procured by him from Mr. Jonathan Sisson, a celebrated artist of that time. See Phil. Trans., rol. 12. — Orig. VOL. LXXXVIII.J PHILOSOPHICAL TRANSACTIONS. 305 = the total length therefore 36.00130 inches, the thermo- — 0.00127 .00135 .00128 meter at 60°.8. Mean = .00130. The interval on the line marked Exch. was shorter than mine by - .0066} .0066 f .0068 > = the total length = 35.9933 inches, the therm, at 6o°.6. .0067 J And the Paris half-toise, which had been supposed by the Academy to be = 38.355 English inches, was found, compared with mine, to be = 38.3561 1 .3563 J- Mean = 38.3561 Inches.* .3559 J The 1st of the preceding observations giving 36.0013") The 2d 35.9933 > Inches. The mean length of Mr. Graham's standard becomes 35.9973 J From the information in the report of a committee of the House of Commons, in 1758, I learnt that Mr. Bird's parliamentary standard had been in the custody of some of its officers, but of whom nobody knew: however, under the authority of the Speaker, who was so good as to furnish me with a room in his house, to make the comparisons in, I at last discovered this valuable original in the very safe keeping of Arthur Benson, Esq., Clerk of the Journals and Papers, and which I * Dr. Maskelyne says, this standard yard of Mr. Graham's was -p^ inch longer on 3 feet than Mr. Bird's divided scale, which he generally made use of in all his operations of dividing ; and, from one made conformably to this of Mr. Bird's, Mr. Troughton divided my scale of 60 inches. This remark seems to agree with my 1st and 3d comparison, but not with the intermediate one. See Phil. Trans. for 1768, p. 324. As I am now on the subject of foreign measure, it may not be quite out of place to say a word on the length of the ancient Roman foot, which I am enabled to do with some precision. Some years ago, when I was in Italy, I had several opportunities of ascertaining the length of this measure, by actual examination of the Roman foot rules, of which I have met with 9, viz. 2 in the Capitol at Rome ; 1 in the Vatican ; 5 in the Museum at Portici, near Naples ; and lastly, one in the British Museum, sent from Naples by Sir William Hamilton. They were all of brass, except one half foot of ivory, with a joint in the middle, resembling our common box or ivory rules : and, by reference to my journal kept at that time, I find the mean result from all the 9 rules, viz. by taking both the whole and the parts of each, (for they were divided into 12 inches, and also into l6ths, or digits), gave, for the length of the old Roman foot, in English inches, correspondent to Mr. Bird's measure, = 11.6063. In confirmation also of this conclusion, and agreeably to the idea of Mons. De La Condamine, in the " Journal of his Tour to Italy," I took the dimensions of several ancient buidings, viz. the interior diameter of the temple of Vesta ; the width of the arch of Severus 3 the door of the Pantheon ; and the width of the base of the quadrilateral pyramid of Cestius, which, it is curious to observe, I found exactly 100 old Roman feet, and 125 feet high. This I do not remember to have seen noticed by any former traveller. The mean result of these experiments gave me 1 1.6 17 English inches. Ditto, as before, from the rules 11 .606 ditto. The mean of the 2 modes of determination is 1 1 .612 ditto. I may add, that in the Capitol is a stone, of no very ancient date however, let into the wall, on which is engraven the length of several measures, from which I took the following : The ancient Roman foot = 11.635 English inches. The modern Roman palm, = 8.82 inches. The ancient Greek foot, = 12.09 inches. — Orig. VOL. XVIII. R R 306 PHILOSOPHICAL TRANSACTIONS. [ANNO 17 Q8. believe had never seen the light for 35 years before. It is a brass rod or bar, about 39 inches long, and 1 inch square, inclosed in a mahogany frame, inscribed " Standard *%£ J 758;** at each extremity of it is a gold pin, of about ^ inch in Geo. 3d diameter, with a central point, and these points are distant = 36 inches. It bears however no divisions; but there was found with it, in another box, a scale divided into 3d inches, with brass cocks at the extremities, for the purpose of sizing or gaging other scales or rules by. Besides these, I found another standard, in size, and in all respects, similar to the last, inscribed 1 760, having been made for an- other committee, that sat in that year; this also was accompanied with a similar divided scale of 36 inches. These bars being too thick to be conveniently placed under the microscopes of my instrument, the interval of 36 standard inches was laid down on my scale with a beam-compass, 2 fine points made, and, compared with Troughton's divisions, was = 36.00023 inches; the thermometer being at 64°. I then examined the other standard, marked t( Standard, 1760," and found it to agree exactly with that of 1758; at least it did not differ from it more than .0002 inch. I was now to examine the old standards kept in the Exchequer: these, Mr. Charles Ellis, Deputy Chamberlain of the Tally Court at the receipt of the Exche- quer, was so good as to supply me with ; viz. the standard yard of the 30th of Eliz. 1588, and also the standard ell of the same date. These are what have been con- stantly used, and are indeed the only ones now in use, for sizing measures of length.* They are made of brass, about 0.6* inch square, and are very rudely divided indeed, into halves, quarters, 8ths, and l6ths; the lines being 2 or 3 hundredths of an inch broad, and not all of them drawn square, or at right angles to the sides of the bar, so that no accuracy could possibly be expected from such measures. However, the middle point of these transverse lines, between the sides of the bar, was taken as the intended original division ; and these divisions, such as they were, were transferred, by a dividing knife, to the reverse side of my brass scale made by Mr. Troughton, the thermometer being at 63°; and, at my leisure afterwards, I found as follows. The ends of these venerable standards having been bruised a little, or rounded, in the course of so many years' usage, I conceived a tangent to be drawn to the most prominent part, which was about the centre or axis of the bar, and this point being referred to Troughton's scale, between 6 and 42 inches, the entire yard of 1588, measuring from one extremity to the other, was found to be shorter than this, by — .007 inch : but these comparisons will be better exhibited in a table, as follows. * There was also a standard yard of Henry vn., but of very rude workmanship indeed; now quite laid by, and at what time last used, no information remains ; but of this more hereafter. — Orig. VOL. LXXXVIII.] PHILOSOPHICAL TRANSACTIONS. 307 Exchequer standard of 1588. Differ, from Trough- ton. Inch. — .007 + .063 — .008 4- .022 — .055 — .036 + .032 + .017 — .001 4- .051 Length in Inches 35.993 18.063 26.992 31.522 33.695 44.964 22.532 33.767 39.374 42.239 Differ, on 36 inches. — .007 + .126 — .011 4- .025 — .059 -.029 + .052 4- .018 — .001 4- .043 Mean difference on 36 inches. Inch. •= 4- 0.015 + 0.016 I Viz. the Exchequer measure is by so J much the longer, or about 1 in 2322. Entire yard I yard, from 24 to 42 inch. . I yard, from 15 to 42 inch. . ■J yard, from 10| to 42 inch. •f| yard, from 8| to 42 inch. Entire ell, from 2 to 47 inch. I ell, from 2 to 24^ inch. . . |, from 2 to 35| inch {, from 2 to 41.375 inch f£., from 2 to 44.1875 inch. . It appears then, from this table, that the ancient standards of the realm differ very little from those that have been made by Mr. Bird, or Mr. Troughton, and consequently, even in a finance view, nothing need be apprehended, of loss in the customs, or excise duties, by the adoption of the latter. I shall now endeavour to show the proportion of the weights that I have used, compared with the standards that were made by Mr. Harris, Assay Master of the Mint, under the orders of the House of Commons, in the year 1758. They are kept in the same custody with Mr. Bird's scales of length, and appear to have been made with great care, as a mean result from a great number of comparisons of the old weights in the Exchequer, which have been detailed at length in that report. Mr. Harris having been of opinion that the Troy pound was the best integer to adopt, as the standard of weight, I venture to conclude that this was the most accurate, and most to be depended on, of all the various weights and duplicates that he made for the use of this committee; for he made them of 1, 2, 4, 8, 16 lb. and of 4-, 1, 2, 3, 6oz. It will therefore be sufficient for my purpose, to compare the 1 and 2 pounds Troy, and their duplicates, with the weights of Mr.. Troughton. I did this, June 2d, 1797; the barometer being at 29.72 inches, and thermometer 670. The result of which was, that The mean weight of 2 lb. Troy, is 11 527.70 grs. And consequently 1 lb. becomes 5763.85 But, from the exam, of the 2 single pound weights, lib. is 5763.7 1 Therefore the mean of all is =s 5763.78 That is, Mr. Troughton's weights are too light by -vrdy.^l — 0.6562 grain on 1000 grs., or 1 in 1523.92 grs. In conclusion, it appears then, that the difference of the length of two pendu- lums, such as Mr. Whitehurst used, vibrating 42 and 84 times in a minute of mean time, in the latitude of London, at 1 1 3 feet above the level of the sea, in the temperature of 60°, and the barometer at 30 inches, is as 59.89358 inches of the parliamentary standard; whence all the measures of superficies and capacity are deducible. That, agreeably to the same scale of inches, a cubic inch of pure dis- tilled water, when the barometer is 29.74 inches, and thermometer at 66°, weighs rr 2 308 PHILOSOPHICAL TRANSACTIONS. [ANNO 1798. 252.422 parliamentary grains; from whence all the other weights may be de- rived. As a summary of what has been done, I hope it may now be said, that we have attained these 3 objects: 1st. An invariable, and at all times communicable, measure of Mr. Bird's scale of length, now preserved in the House of Commons; which is the same, or agrees within an insensible quantity, with the ancient stand- ards of the realm. 2dly. A standard weight of the same character, with reference to Mr. Harris's Troy pound. 3dly. Besides the quality of their being invariable, without detection, and at all times communicable, these standards will have the additional property of introducing the least possible deviation from ancient practice, or inconvenience in modern use. Before closing this paper, after having said so much on the subject of weights and measures, it may not be improper to add a few words on a topic which, though not immediately connected, has some affinity to it; I mean the subject of the prices of provisions, and of the necessaries of life, &c. at different periods of our history, and in consequence the depreciation* of money. Several authors have touched in- cidentally on this question, and some few have written professedly on it; but they do not appear to have drawn a distinct conclusion from their own documents. It would carry me infinitely too wide, to give a detail of all the facts I have collected: I shall therefore content myself with a general table of their results, deduced from taking a mean rate of the price of each article, at the particular periods, and af- terwards combining these means, to obtain a general medium for the depreciation at that period; and lastly, by interpolation, reducing the whole into more regular periods, from the Conquest to the present time: and, however I may appear to descend below the dignity of philosophy, in such economical researches, I trust I shall find favour with the historian, at least, and the antiquary. * The various changes that have taken place, by authority, in different reigns, either in the weight or alloy of our coins, are allowed for in the subsequent table. — Orig. VOL. LXXXVIIJ.] PHILOSOPHICAL TRANSACTIONS. 309 Mean Appre- ciation by Inter- polation. -• 0 c ■si O) c, o^ 0, c o> " or: 0 O 0 ^ 1 Year of our Lord. ^5 Ot 'O 00*»'O Oj O, i— O O O. C ^1 «£• ♦Ob si— *. 26 34 43 51 60 68 77 83 88 94 100 144 188 210 238 257 287 314 342 •384 427 496 531 562 * 1 n 1 1 h 1 j 1 t r > 1 i ' L •> i 1 ? 1 1 1 • > 1050 1100 1150 1200 1250 0 0 o» to 1—" «• O O c JO 0 — c >- f*b O JO *03H< JOoo-vJ . 0 *>o^ Oi?- 1 as 0 a s O & a" 5' X a iS. & ■ 0 M V p > M O £3 > H O t-i H H DC M I— ( O H O < 3 MH O CO > 1 MB O f H CO £§ O t— 1 a H H M CO 1300 1350 1400 1450 1500 1550 l600 16'50 1675 1700 1720 1740 1750 1760 05 00 * 00 O O GO 00 * >-* o» Ow O 0 0 09 00 05 •> O 0 cr>t^* *• 0 it^o^i -05 ^00 O^ " 0 OO OOO C Pb O 1— > OS 1-1 NN 00 09 ft- ■MUMH 5* 1770 1780 1790 1795 J 8001 Oi £oo 0 1— 1 m* » (— '» Ml « 0« *• * O O 0 to Ml W if* O 000 0 0 fib 0 o< 0-.* jo rt2 jo I* 0 cr>»- as c 0 ?- w 0 crq *•"> integer, viz. ■ Co w O O O a< 09 iff oj O w 0 Oo Oj OO 01 O O O JO t-i O O i-" J" O OO Oi"^ 0 p- 1 0 0 1 9 | •5 1— 1 M 00 O, 10 to e» t— l- CH C 00 O} 00 M 09 O OOO ? O GO * JO 09 09 A. X 2 t 1— 1 0 c, KkOl «OoO) I-1 to «• 09 c- »— O O ?• O Oj O C OOl^ O- O 0 I W 1— ' O<0H 0 c» 0>m 09 lotOfr-wtOM O JO 0 O JO A, 0 1 c n • » jo 1CIW vO 00 U) O O WO O O 000 IA Oo 00 ^ OO J" 0 Pa £ 5i8 2 092 00 09 O O OO" JO 63 *°o ^ P- 0 "9 WCfl J. f» P CfS ft 3 pj _~i po S 1 j to J> to w <0 0 «" * 6 • w Mean Deprecia- tion from these J 2 Articles. $ 09 •f- OS JO JO O W 00 IBH jo 0 »g Beef & Mutton, per lb. £ M M> O O O M> M> O. JO — O CO O (CO- OOOOO O }» j Oi Oj >t>- OO 00 JO ft. Labour in Hus- bandry per day. 1 1 *> 63 mi O <© 09 -«* JO 00 0 00 ° 9 8- a O "73 0 1-1 g a Q. O 3" 5" crq g. a ^ 2. 0 Q ° a a 0^ ~>* n • t c O. JO <© 00 JO £* JO 09 M CO. a> O O) JO 12 Miscel- laneous Articles. 3 s O. >— • «t- JO O Oi O 1 09 o> to to Tr1 *« 00 oo Ml _, 8 2 Day Labour. 1 0. 09 M> 09 JO *- 00 *o *S JO M O 8 "^ °> OS ft 3 6 O bo S Hi 0, ^3 Si. fb ~. ft> o f» O o ^ S if 3 S fti ^5 ft- >» ^ » ^ "» ft- Qrq ft> ft* ft -t i S5> n ft ft Q a- ^^ a © ft- © "X. t) © ©' ft rs Q 9- <^ 8> 3 ^> ft- ps. ft- ft) b © 1 ©^ ft a, ft 310 PHILOSOPHICAL TRANSACTIONS. [ANNO 1798. Appendix. — Since writing the preceding Memoir, I have had an opportunity of examining 3 other scales, divided into inches, or equal parts, of considerable authority in this country, having been executed by the late Mr. J. Bird. I have also compared the old standard in the Exchequer, of the time of Hen. 7th, and which is considered to be the most ancient authority of this sort now subsisting. The first of those scales belonged to the late General Roy, and was purchased by him at the sale of Mr. Short's, the celebrated optician ; it was used by him in his operations of measuring a base line on Hounslow Heath. It was originally the property of Mr. G. Graham, has the name of Jon. Sisson engraven on it, but is known to have been divided by Mr. Bird, who then worked with old Mr. Sisson. It is 42 inches long, divided into lOths, with a vernier of 100 at one end, and of 50 at the other, giving the subdivisions of 500ths and lOOOths, of an inch. The 2d is in the possession of Alex. Aubert, Esq. and formerly belonged to Mr. Harris, of the Tower ; contains 6o inches, divided into lOths, with a vernier, like that of the preceding. It is 1 inch broad, and 0.2 thick. The 3d was presented by Alex. Aubert, Esq. and the late Adm. Campbell, Mr. Bird's executors, to the b. s., in whose custody it now remains. It consists of a brass rod, 92.4 inches long, 0.57 inch broad, and 0.3 inch thick ; bearing a scale of 90 inches, or equal parts, each subdivided into 10, with a vernier at the commencement, being a scale of 100 divisions to 10 J tenths. This has been called Mr. Bird's own scale, viz. made for his own use ; and was the instrument with which it is said he laid off the divisions of his 8-feet mural quadrants. It is probable that Mr. Bird made many more of these scales, now in the hands of private persons. In comparing General Roy's (Bird's) scale with Mr. Troughton's, I found 42 inches of the former were = 42.00010 inches on Troughton's; the thermometer 51°.7 ; 36 inches were consequently = 36.00008. Inches. And 12 inches on the 1st foot were equal to the 12 inches from 12 to 24 on ) __ 0_03 __ Troughton's scale j ■- ,yyy' The 2d foot + .0006 12.0006 The 3d foot - .0004 1 1.9996 The last foot + .0006 12.0006 The mean foot, therefore, in General Roy's scale, taken from 4 different feet, compared ) J2 00012 with Troughton's, between the 12th and 24th inch, is as 12 to j That is, General Roy's scale is longest on 1 foot by so much, and longer on 3 foot by 00036 And the greatest probable error from the inequality in the divisions is about .0005 And the mean probable error about .' .0003 Mr. Aubert's scale, compared with Mr. Troughton's, was as follows : 58 inches were equal to 57.9982 inches on Troughton's ; thermometer at 51°.0; viz. Mr. Bird's measure was shortest .0018 ; or, shortest on 36 inches = .0012, Inches. And 12 inches, or 1st foot, on Mr. Aubert's = 1 1.9999") 2d foot, = 12.0005 on Mr. Troughton's scale, 3d foot, 11.99£)6 I from 6 inches to 18 inches; 4th foot, *. 12.0019 [ the thermometer being at 5th foot, , 12.0006 50°.0. Therefore the mean foot is ,. 12.0005 j VOL. LXXXVIII.] PHILOSOPHICAL TRANSACTIONS. 311 The greatest error in this scale appears to be about = .00 1 2 And the mean probable error = .0006. The Royal Society's scale, compared, was as follows : 58 inches on Mr. Bird's were equal to 57,99912 inches on Mr. Troughton's , thermometer 50°.5 ; viz. Mr. Bird's measure was shortest .00088 Or shorter on 36 inches 00054 32 inches on the same were equal to 31 .99967 viz. Mr. Bird's was shortest by 00033 Or, on 36 inches, by 00037 The mean of these two comparisons is 00045 And, by so much, is Mr. Bird's scale shorter, in 3 feet, than Troughton's. Inches. And 12 inches, or 1st foot, of the Royal Society's scale, is . . = 12.00013 ' 2d foot of ditto = 11.99957 3d foot of ditto =12.00027 ^ ,, , , iU aiu c 4. c At.,. .,' nnni v on Troughton's scale : the ££*£•& :::::::::::::::::::: = WS f th™-*t51°- 6th foot of ditto = 11.99823 7th foot of ditto = 12.0000Q_ The mean of these 7 feet is =11 .99982 And the greatest error in these divisions = .0008 And the mean probable error = .0004. Lest however it should be suspected that Mr. Troughton's scale, with which I have made these comparisons, is not sufficiently correct for this apparent preference, I will now give the result of my examination of that scale, from one end to the other. I set the microscopes to an interval of nearly 6 inches, correctly speaking, it was 6.00013 inches, taken from a mean of the whole scale ; and, comparing this interval successively, I found as annexed. Mean of a11 = 6.00013. Whence it appears, that the greatest probable error, without a palpable mistake, in Mr. Troughton's divisions, is = .00033 inch ; against which, the chance is 9 to 1 ; and the mean probable error = .0001 6 ; and that it is 4 to 1 the error doth not exceed 100900 inch. This accuracy is about 3 times as great as that of Mr. Bird's scales, and about equal to that of the divisions of my equatorial instrument, made by Mr. Ramsden, in 1791. I now proceed to the examination of the standard rod of Henry 7th, which is an octangular brass bar, of about 4- an inch in diameter, with one of the sides rudely divided, into halves, thirds, quarters, 8ths, and l6ths ; and the first foot into inches. Each end is sealed with a crowned old English H, and hence is • concluded to be of the time of King Henry 7th, viz. about 1490, but is now become wholly obsolete, since the introduction of the standard of Queen Error, or Dif- Inches. Inches. ference from the mean. iz. from 0 to 6 = 6.00025 + .00012 6 to 12 = 6.00013 .00000 12 to 18 = 6.00020 + .00007 18 to 24 sa 6.00000 — .00013 24 to 30 = 6.00007 — .00006 30 to 36 = 6.00033 + .00020 36 to 42 sb 5.99980 - .00033 42 to 48 = 6.00020 + .00007 48 to 54 = 6.00010 — .00003 54 to 60 sb 6.00023 + .00010 312 PHILOSOPHICAL TRANSACTIONS. [ANNO 1798. Elizabeth; but such as it is, I have thought proper to examine it, and find as follows : Inches. On this rod, -£., or the 1st foot, is equal to 11.973 on Troughton's. the 2d foot is 11 .948 the 3d foot is 12.047 Difference. Error, or difference 011 3 feet. — .011 -.033 — .054 - .108 - .079 — .118 - .063 — .084 — .057 - .065 — .085 - .091 -.034 — .034 The mean foot is 1 1.989 \ yard, or 18 inches = 17-S46 £ yard, or 24 inches = 23.92 1 I yard, or 27 inches = 26.937 ■J yard, or 31 J inches = 31.443 -f-§- yard, or oof inches = 33.665 Entire yard, or 36 inches = 35-966 And the mean yard as 35.924 Mean — .076 And by so much Mr. Troughton's measure is the longer. And the probable error, in the divisions of this old standard, is about -j-f-^ inch. It may now be desirable to see the comparative lengths of these various stan- dards and scales, reduced to one and the same measure, viz. Mr. Troughton's. Inches on Probable error TroughtonV Difference. in divisions. 36 inches, on a mean, of Hen. 7th's standard of 1490, are equal to . . . 35.924 — .076 .03 of standard yard of Eliz. of 1588 36.015 4- .015 .04 of standard ell of ditto, of 1 588 36.016 -f .016 .04 -* of yard- bed of Guildhall, about 1660 36.032 4- .032 *of ell-bed of ditto, about 1660 36.014 + .014 *of standard of clock-makers' company, 1671 35.972 — .028 — — — *of the Tower standard, by Mr. Rowley, about 1720 36.004 4- .004 ' of Graham's standard, by Sisson, of 1742, viz. line e = 36.0013 4- .0013 of ditto, ditto, viz. line exch = 35.9933 — .0067 i of Gen. Roy's (Bird's) scale c all made, probably, "^ = 36.00036 4- .00036 .0003 . — of Mr. Aubert's ditto, ditto I between the years > = 35.99880 — .00120 .0006 of Royal Society's ditto, ditto I 1745 and 1760. J = 35.99955 — .00045 .0004 ■ of Mr. Bird's parliamentary standard, of 1758 = 36.00023 4- .00023 ■ of Mr. Troughton's scale, in 1796 = 36.00000 .00000 .0001 Hence it appears, that the mean length of the standard yard, taken from the first 7 instances in this table, agrees with the quantity assumed by Mr. Bird, or Mr. Troughton, to within -j-oVo inch, but that the latter is the longest. IX. A new Method of computing the Value of a Slowly Converging Series, of which all the Terms are Affirmative. By the Rev. John Hellins, F. R. S. p. 183. 1. The computing of the value of the series ax -\- bx1 -j- ex3 -f- dx4 -f- &c. ad infinitum, in which all the terms are affirmative, and the differences of the co- efficients o, /', c, &c. are but small, though decreasing, quantities, and x is but little less than 1 , is a laborious operation, and has engaged the attention of some eminent mathematicians, both at home and abroad, whose ingenious devices on the occasion entitle them to esteem. Of the several methods of obtaining the value of this series, which have occurred to me, the easiest is that which I am now to describe, by which the business is reduced to the summation of 2, or 3, or more * These four quantities are taken from Mr. Graham's account, in the Phil. Trans, vol. 42. — Orig. VOL. LXXXVIII.] PHILOSOPHICAL TRANSACTIONS. 313 series of this form, viz. ax — bx2 + ex3 — dx\ &c. and one series of this form^ viz. pxn -j- qx2n -\- rx3" -j- &c. where n is = 4, 8, ] 6, 32, or some higher power of 2. The investigation of this method is as follows. 2. The series ax -f- bx2 -J- ex3 + dx4 -\- ex5 + /^6 + &c« is evidently equal to the sum of these two series, viz. ax — bx2 + ex3 — eta4 + ex5 — fx6, &c. * + 2bx2 * -f 2<&?4 * + 2fx6, &c. of which, the value of the former is easily attainable, by the method so clearly ex- plained, and fully illustrated, by Mr. Baron Maseres, in the Philos. Trans, for the year 1777 ; and the latter, though it be of the same form with the series first pro- posed, yet has a great advantage over it, since it converges twice as fast. On this principle then we may proceed to resolve the series 2bx2 -f- 2dx4 -f- 2fx6 + Q,kx9 -f 2kx10 -f 2mx12 -L. &c. into the two following : 2bx2 — 2dx4 + Qfx6 — 2hx8 -f 2kx10 — 2mx12, &c. * + 4dx4 * + 4hxs * + 4mx12, &c. where again the value of the one may easily be computed ; and the other, though it be of the same form with the series at first proposed, yet converges 4 times as fast. And in this manner we may go on, till we obtain a series of the same form with the series at first proposed, which shall converge 8, 16, 32, 6*4, &c. times as fast, and consequently a few terms of it will be all that are requisite. An example, to illustrate this method, is here subjoined. 3. Let it be proposed to find the value of the series x -\- — -\- —- -\- -\ (- *ft , . q -~- + &c. ad infinitum, when x = — . o 10 4. In order to obtain the sum of this series, with the less work, it will be requisite to compute a few of the initial terms, as they stand. For, if we begin the opera- r2 r3 _4 tion with computing the value of # 2~ + T """ T* ^c* ^ tbe differential series before mentioned,* the values of d', d/;, d'", &c. will be -, ^-, y^, &c. respec- tively, i. e. -£-, •£-, -£-, &c. which is a series decreasing so very slowly, that the only advantage obtained by this transformation of the series is in the convergency of the powers of instead of the powers of x, which indeed is very great ; for, x beinS = lo' TTT is m f§ ; so that the new ■*** J§ + * ' (^>2 + * • (|)3 + * • (^)4 + &c« though = J5 ~ * ' (£)* + i • (^)3 - * • (^,)4' &c« yet converges more than 7 times as swiftly. But, if we begin the work by computing the * The theorem best adapted to this business is the following ; viz. ax — bx* + cxs — dx*, &c. = ax d' x'' b" xi d'" x* X+T + JTTxr + UTW + JTTxy + &c' D being = a ~ b> D - * ,n . *A e> £ = a — 3b + 3c — d, &c. See Scriptores Logarithmici, vol. 3, p. 290, where b, c, d, &c. denote the •ame quantities that a, b, c, &c. do here. VOL. XVIII. S S 314 PHILOSOPHICAL TRANSACTIONS. [ANNO 1798. first 8 terms of the series, as they stand, and then compute the value of X X* X^ x^ g — -jq + — ~~ "12 * &c* ad *nmiitum> by the same theorem, the values of d', d", tTj, &c. will be — , j^yy, gj^jl^ &c- wnich is a series decreasing, for a great number of its terms, much more swiftly than the powers of — , and, in the 10 9 first 7 terms, much more swiftly than the powers of ~. The value of the series I ' To "" To * ("io^ + 17 ' (jo^ ~ I? * ("io^' &c' is therefore = the series 9 * IP + 9^ ' ^ + ***rt * kj# + 9^Ti~2 ' ^ + &c* the first ^ terms of which converge above 14 times as swiftly as the other; or, in other words, the first 7 terms of it will give a result much nearer the truth than 100 terms of the other. And if, instead of the first 8 terms of the proposed series, the first 24 terms were computed, as they stand, and then the value of the series i5---S+|--!5> &c- by its^uivalent'^-TTT+-i3l6--(TW + jnw-(TTW + imm* -irhy + &c- the raPid decrease of the co- 11 2 efficients — -, g , g , &c. compounded with the decrease of the powers of ' . > (in tne present case = the powers of -^,) produces such a very swiftly converging series, that 8 terms of it will give the result true to 1 1 places of de- cimals. On these principles Mr. H. proceeds to compute the terms of these series, and to collect them together ; in doing which he employs some ingenious contrivances, to methodize and facilitate the operations. After which the ingeni- ous author concludes the whole process as follows. The values of the several parts, into which the proposed series has been resolved, being now so far obtained that we have only to multiply each by its proper factor, viz. the numerical value of xs, a:16, x3z, &c. and add the products together, to get its sum ; this therefore is now to be performed. And, in this part of the calcula- tion, several multiplications may be saved, and no larger factor than x8 be used, by attending to the method described by Sir Isaac Newton, in his Tract De Analysi per iEquationes infinitas ; p. 10 of Mr. Jones's edition of Sir Isaac's Tracts; or p. 270, vol. 1, of Bishop Horsley's edition of all his works. The manner in which this is to be done will appear, by collecting the several parts from the preceding articles, and exhibiting them in one view, thus : a + B.r8 + c*10 + (« + d) X tf24 + (g + e) X x32 + yx" + (J + p) X a48 = the sum of the proposed series. Now, 1st. Calling I + p, z', and multiplying by x83 we have z x8 = 0*26584,70242 X 0-43046,721 = 0-11443,84267,9.— 2dly. Putting y -f z' x8 = z", and multi- plying by x8t we get z" x8 = 0*15172,24360,1 X 043046,721 = 0'0653 J, 15337,2. "— 3dly. Putting 6 -f e + z" x8 = *'", and multiplying by .r*, we get zf,/ x8 == VOL. LXXXVIII.] PHILOSOPHICAL TRANSACTIONS. 315 0*20827,01655,4 X 0*43046,721 = 0*08g65,34770,9. — 4thly. Putting « + d + z'V = siv, and multiplying by a:8, we get ziv x8 = 0*28046,43895.9 X 0.43046,721 = 0*12073,07232.90. — 5thly. Putting c -f zir x8 = zv, and multiplying by a?8, we get zv x8 = 0*38085,19524,75 X 0-43046,721 = 0*16394,42774,05. — 6thly. Putting b + zv x8 = zvi, and multiplying by xs} we get zyix8 = 0*60806,50444,24 X 0*43046,721 = 0*26l75,20631,73. Lastly, to this product add a = 2*04083,30298,21, and we have the value of the series proposed = 2*30258,50929,94, which is true to twelve places of figures. It may not be improper to remark, that this degree of accuracy is much greater than is requisite, even in astronomy ; for which, as well as for most other purposes, 6 or 7 places of figures are sufficient: and to that degree of exactness the value of the proposed series might have been obtained, by less than a 4th part of the labour that has been taken above. But it was the intention to show, that the value of a very slowly converging series, of which all the terms are affirmative, may, by the method now described, be computed to 10 or 12 places of figures, in the space of a few hours. Meteorological Journal, kept at the apartments of the R. S. By order of the President and Council, p. 201. Six's Therm. Thermometer Thermometer "Pi _ • without. without. within 1797. i j 0 c -a 0 0 S.Sf O 1- ** «-& S3 0 4-> to 4_j ca bC 2*1 0 CO -C i-J s and consequently a very large one. XII. Of the Orifice in the Retina of the Human Eye, discovered by Prof. Soem- mering. With Proofs of this appearance being extended to the Eyes of other Animals. By Everard Home, Esq., F. R. S. p. 33'2. Having received a particular account of this discovery, in a very obliging letter from Mr. Maunoir, an eminent surgeon at Geneva, which contains, I believe, the material information published by Mr. Soemmering; I shall transcribe that part of the letter, which is as follows: "The war being an obstacle to a free communication between England and the continent, you are not perhaps acquainted with a new VOL. LXXXVIII.] PHILOSOPHICAL TRANSACTIONS. 827 discovery in the anatomy of the human eye, made by a professor of Mentz, Mr. Soemmering; permit me therefore to say something on the subject. He was dis- secting, in the bottom of a vessel filled with a transparent liquid, the eyes of a young man who had been drowned, and was struck on seeing, near the insertion of the optic nerve on the retina, a yellow round spot, and a small hole in the middle, through which he could see the dark choroides, looking at the surface of the retina which covers the vitreous humour. He dissected other human eyes, and constantly, when the dissection was carefully made, found the hole of the retina seemingly at the posterior end of the visual radius, nearly 2 lines on the temporal side of the optic nerve, and the hole surrounded by the yellow zone, of above 3 lines in diameter. The hole of the retina is not directly seen, being covered with a fold of the retina itself. An anatomist of Paris dissected many eyes of quadrupeds and birds, and found the yellow spot and hole in no animal but the human kind. Should you think that nature has intended this hole to grow large when the eye is opposed to a strong light, and thereby cause a great part of the rays to fall on the choroid, and vice versa, when the eye is in darkness? And the want of such a con- struction in animals, is it owing to a greater power of augmenting or diminishing the pupil, than in men? If Messrs. Mariotte and Le Cat should come to life again, they would find, in that hole, the explanation of the phenomenon of the 2 cards, one disappearing at a certain distance from 1 eye, &c. which may be explained by saying, that where the optic nerve enters the ball, there is no choroid, and so no vision. " I dissected some human eyes a short time after I had read the discovery, and found the spot, the ruga concealing it, and the yellow zone. The best way I think to see them, is to take oflf the half posterior part of the sclerotica, then the correspondent part of the choroid; both must be cut round the insertion of the optic nerve. The retina is to remain bare and untouched, sustaining alone the vitreous humour ; then you may see the round spot, that reaches the optic nerve, and a fold of the retina, marking a diameter of the spot. Then, if you press the ball a little with your finger, so as to push the vitreous humour rather near the bottom of the eye, the ruga is unfolded, and you will see the hole perfectly round, of -^ of a line in diameter, and its edges very thin. All this can be seen on the inside of the eye, but not so perfectly; and in that case you must make the ob- servations in water." Many months elapsed, after the receipt of this letter, before I could procure an eye in a proper state for observing this aperture in the retina; but, in the course of last month several opportunities offered, and I saw the appearance described by Mr. Maunoir very distinctly. The mode I adopted for examining the retina, was that of removing the transparent cornea; then taking away the iris, and wounding the capsule of the crystalline lens, so as to disengage the lens, without removing that part of the capsule which adheres to the vitreous humour; by which means, the retina remained undisturbed, and could be accurately examined, when a strong 328 PHILOSOPHICAL TRANSACTIONS. [ANNO 1798. light was thrown into the eye. The aperture in the retina, surrounded by a zone with a radiated appearance, was distinctly seen, on the temporal side of the insertion of the optic nerve, and about £ of an inch distant from it, apparently a little below the posterior end of the visual radius. The aperture itself, in this view, was very small. After having viewed it in 2 different eyes, I took an opportunity of showing it to Sir Jos. Banks and Sir Charles Blagden, who both saw it with the same degree of distinctness. At first, I believed it necessary to have a very fresh eye for demonstrating this aperture; but I have since found, that it is more readily seen in an eye 2 days after death; the zone, which is the most conspicuous part, being of a lighter colour the first day, than it is on the 2d. I have also succeeded in preserving the pos- terior part of the eye in spirits, without destroying the appearance of this aperture. I am induced to make this remark, by recollecting that a celebrated anatomist of Edinburgh denied, in his last publication, that the anterior lamina of the cornea can be separated from the others, as a continuation of the tendons of the 4 straight muscles of the eye, for no other reason than because he could not succeed in the demonstration of it; the failure 'probably arising from the eye not being sufficiently fresh to admit of such a separation. In separating the vitreous humour from the retina, I found a greater adhesion at this particular part; and, when the vitreous humour was removed, the retina was pulled forward, forming a small fold, in the centre of which was this aperture. This doubling was sometimes produced by en- deavouring to cut through the vitreous humour, to disengage the crystalline and its capsule. After having made the preceding observations on this singular appearance in the human eye, I found, in Dr. Duncan's Annals of Medicine for 1797, an account of a publication concerning it by Professor Reil, entitled, the plait, the yellow spot, and the transparent portion of the retina of the eye. After these are described separately, the following circumstances are mentioned. " Soemmering takes this appearance to be a real hole. Buzzi, on the contrary, thinks that it is merely a transparent and thin portion of the retina. Michael is seems to agree with him. Reil and Meckel are rather in favour of the existence of an actual hole. Michaelis saw the plait more distinctly in foetuses of 7 or 8 months, than in adults; and the transparent portion lay concealed within it, but the yellow spot was wanting: nor is it to be observed in the eyes of newly-born children. After the first year, it becomes somewhat yellow, and the depth of the colour increases with the age of the subject. Soemmering says that this spot is pale in children, bright yellow in young people, and becomes again pale in old age. Its degree of saturation seems to be intimately connected with the state of vision: it constantly diminishes, in proportion as vision is obstructed. Where one eye only is diseased, in it the yellow spot is wanting, and the plait is small and wrinkled; while in the sound one they are rather more distinct than usual. Michaelis discovered no vestige of these ap- pearances in the eyes of dogs, swine, or calves." VOL. LXXXVIII.] PHILOSOPHICAL TRANSACTIONS. 329 Professor Reil's mode of dissecting the eye, to show the aperture and plait, is exactly similar to that mentioned in Mr. Maunoir's letter. It will appear, from the account of this orifice in the retina, which precedes these observations of Pro- fessor Reil, that the plait so particularly mentioned, is an artificial appearance, which takes place in the dissection of the eye, and arises from the circumstance of the vitreous humour adhering more firmly to the edge of this orifice, than to any other part of the retina; so that the smallest motion of the vitreous humour, in consequence of dividing it, or removing the choroid coat, produces a plait, by pulling forwards this portion of the retina. What is said of the colour of the yellow spot, and of the difference of opinion, whether it is a hole or a transparent portion of the retina, I shall consider more fully in another part of this paper. After having ascertained the appearance of this aperture in the human eye, and found what appeared the best mode of seeing it, I determined to investigate this subject in the eyes of other animals. The monkey was the first animal which I procured for observation; being led, from previous knowledge in comparative anatomy, to believe that the structure of its eye must bear a very close resemblance to that of the human subject. The eye was examined immediately after the death of the animal, and was prepared in the same way that I have already described the human eye to have been for this purpose; so that the concave surface of the retina appeared in its most natural state, and the vitreous humour, being entire, kept it expanded, and free from rugae. On the first view, nothing was to be seen but one dark surface, surrounding the entrance of the optic nerve. Two hours after death, the retina became sufficiently opaque to be distinguished, and immediately after, the orifice was visible, appearing to be an extremely small circular aperture, without any margin; but in 4- an hour more, the zone had formed, which, when very accurately examined in a bright light, had an appearance of four rays, at right angles, as expressed in pi. 5, fig. 7- Its situation, respecting the optic nerve, was precisely the same as in the human eye. As I considered this to be a fact of some importance, since it proved the aperture in the retina to be a part of the structure of the eye, generally, and not a peculiarity in the human eye, I re- quested Sir Jos. Banks, Sir Chas. Blagden, and Dr. Baillie, to examine it: to all of them it appeared very distinct. After having shown it to those gentlemen, and having an accurate drawing made of it, I preserved that portion of the eye in spirits; where the aperture in the retina can still be distinctly seen, but the radiated appearance is lost. In the eye of a bullock, prepared in the same manner, I looked in vain for a similar appearance: if it existed, and bore any proportion to the size of the eye-ball, as it appears to do in the human eye and that of the monkey, it must have been very visible. The concave surface of the retina was examined in different lights, under a variety of circumstances, and by magnifying glasses of different powers, but still no aperture could be discovered. I was however very much struck, while looking at the optic nerve, to see something in the vitreous humour, in conse- vol. xviii. U u 330 PHILOSOPHICAL TRANSACTIONS. [ANNO 17Q8. quence of a person accidentally shaking the table, that had not been before ob- served. This proved to be a semi-transparent tube, resembling in its coats a lymphatic vessel, rising from the retina, close to the optic nerve, on the temporal side of its insertion, and coming directly forwards into the vitreous humour, in which it was lost, after being distinctly seen for -5Vtns of an inch of its course. Its appearance is accurately delineated in fig. 8. This tube is not so distinctly seen in the eye immediately on the animal's death, as some hours after; and is much more obvious in some eyes than in others. As the coats of the tube must be nearly the same in all eyes, this difference probably arises from its contents not always having the same degree of transparency. When the eye has been kept 24 hours after the animal's death, there is an appearance of a zone of a circular form, a shade darker than the rest of the eye, in which the optic nerve is included: when this zone, which is nearly -3-Vtns of an inch in diame- ter, is attentively examined, the tube I have described is exactly in the centre of it. The tube seems to be confined by the vitreous humour, while that humour is entire, and only to move along with the central part of it; and in some instances, when the vitreous humour is divided, the tube falls down. Its attachment at the retina appears stronger than its lateral connection with the vitreous humour; for when I coagulated the vitreous humour in spirits, and separated it from the retina, I found the tube was left with the retina, but on being touched was easily torn. In the sheep's eye there is a similar tube, in exactly the same situation, respect- ing the optic nerve, but much shorter, and much less easily detected. It does not appear to be more than -^th °f an mcn in length, before it is lost in the vitreous humour. After having seen the tube distinctly in 2 different eyes, and having had a drawing made of it, I looked for it in several others, without finding it: but, examining an eye from which the crystalline lens had not been removed, only an aperture made into the vitreous humour, by removing a portion of the ciliary pro- cesses along with the iris, the tube was distinctly seen. The weight of the lens probably pulled forward the vitreous humour, and kept the short tube erect, in its natural situation. In the sheep there is no appearance of a zone surrounding the tube. These facts, though few in number, are sufficient to prove, that this orifice is not peculiar to the retina of the human eye; and that its situation in man and in the monkey is the same: in them, it is placed at some distance from the optic nerve; but in some other animals, its situation is close to that nerve, and it puts on the appearance of a tube, instead of an orifice. There is one circumstance which is curious, and which it will require further information on this subject to explain ; the yellow zone, found in the human eye and that of the monkey, is not met with in any other animal which I have examined. Having stated the facts, and also the opinions of other anatomists, that have come to my knowledge, as well as my own . observations, on this orifice in the retina of the human eye, discovered by Mr. Soemmering, and having added to these, several new facts respecting it in other VOL. LXXXVIII.] PHILOSOPHICAL TRANSACTIONS. 331 animals, I shall draw some general conclusions from the whole, with a view to show that the conjectures which have been made, respecting its use, are probably erroneous. I shall afterwards point out several reasons for considering it as the orifice of a lymphatic vessel intended to carry off the vitiated parts of the vitreous humour and crystalline lens. In the human subject, as no examination can be made for some considerable time after death, it is impossible to ascertain what is the real state of this orifice in the living eye, and what changes take place in it after death ; we only learn, that the tinge of yellow surrounding the orifice is very slight, when the eye is examined recently, and that the next day it becomes much deeper. These points appear to be satisfactorily cleared up, by the examination that was made of the monkey's eye, as it was begun before the parts had lost the appearance belonging to them as living parts. In that state the retina was transparent, and no orifice could be seen; so that the orifice is rendered visible by remaining transparent, while the surround- ing retina becomes opaque. This appears to decide the dispute between Messrs. Soemmering and Buzzi ; for if this part does not undergo the change peculiar to the retina, we must consider the retina as wanting there. After the orifice is thus rendered visible, the yellow tinge is wanting, and does not take place for several hours, and even then is fainter than it becomes afterwards; which appears to be sufficient evidence, that this tinge is the effect of some change after death, and cannot therefore have any effect on vision. The orifice has been supposed to account for a small object becoming invisible, when placed at a certain distance from the eye, and brought opposite a particular part of the retina. This however cannot be the case, as its situation in the retina does not correspond with the part opposed to the object, when rendered invisible. The orifice itself is probably too small to produce any defect in vision, as the trunks of the blood-vessels which ramify on the retina cover a larger space than this orifice for a considerable extent, without obstructing the sight of any part of the object. While my observations were confined to the human eye, I was led to consider this orifice as a lymphatic vessel, passing from the vitreous humour through the retina, but could bring no absolute proof of its being so. This opinion was strengthened by finding, that in the monkey, the orifice was only rendered visible when the retina became opaque; and it has since been corroborated, by a distinct tube being met with in the eyes of sheep and bullocks. That a change must be constantly taking place in the crystalline and vitreous humours, to preserve to them the necessary degree of transparency, can hardly be doubted ; and that the absor- bent vessels which perform that office should have one common trunk, which follows the course of the artery and vein, perfectly agrees with what takes place in other parts of the body. In the human eye, and that of the monkey, the artery is in the centre of the optic nerve; but that would have been too circuitous a course for the lymphatic vessel to follow, and by going through the retina, at some distance from the nerve, it can pass out of the orbit with the blood-vessels that go through uu 2 332 PHILOSOPHICAL TRANSACTIONS. [ANNO 1798. the foramen lacerum orbitale inferius. In the bullock and sheep there is a plexus of vessels surrounding the optic nerve, and the tube dips down, close by the optic nerve, probably to accompany them. From the observations made by Michaelis, of the yellow spot not being visible in foetuses, or in infants under a year old, or in eyes that are blind, also of its being brighter in young people, and paler in old, it would appear, that it is only when the eye is capable of performing its functions, that there is any stain communicated to the retina. The drawings from which the figures are engraved, were made from preparations of the eye lying in water, with a strong light shining on the prepara- tion. In making the drawings, the principal object was, procuring a distinct view of the parts surrounding the optic nerve; when this could be obtained, the situa- tion of the eye itself was not attended to. Fig. 5, pi. •*>, is a transverse section of the human eye, immediately before the ciliary processes. The retina is viewed through the posterior portion of the capsule of die crystalline lens, a, The ter- mination of the optic nerve, b, The aperture in the retina, discovered by Professor Soemmering. Fig. 6, A longitudinal section of the left eye in the human subject, to show the relative situation of the aperture in the retina to the entrance of the optic nerve, and the mode in which it appears to pro- ject, when the vitreous humour is disturbed, a, The termination of the optic nerve, b, The aperture in the retina. Fig. 7, A transverse section of the eye of a large monkey, to show the aperture in the retina : its situation is the same as in the human eye. The zone has the appearance of a star with 4 rays, a, The entrance of the optic nerve, b, The aperture in the retina. Fig. 8, A transverse section of the eye of a bullock, to show that there is a semi-transparent tube projecting from the edge of the entrance of the optic nerve, into the vitreous humour. This tube is surrounded by a zone, with a distinct margin : it is situated on the temporal side of the optic nerve. Fig. 9, A transverse section of the eye of a sheep, to show that there is a similar tube as in the bul- lock, in the same situation, but much shorter, and without the surrounding zone. XIII. On a very Unusual Formation of the Human Heart. By Mr. J. Wilson, Surgeon, p. 346. It is well known that the circulation of the blood throughout the body, and exposure of it to the atmospheric air in respiration, seem in most animals to be necessarily connected; but are not equally so in all. They are so much connected in the human subject, and in most quadrupeds, that after birth there is a double heart; viz. one for the circulation of the blood throughout the body, to be sub- servient to the various purposes of life and growth; the other for its circulation through the lungs, where it undergoes a change which is essential to its general circulation through the body : these 2 circulations, in the natural state, bear an exact proportion to each other. Instances however have occurred, even in the human subject, where this exact proportion has not been preserved; yet life has been prolonged for some years, but in a feeble and imperfect state. In some of these instances, the pulmonary artery has been smaller than usual, so that much less than the natural quantity of blood was exposed to the influence of the air in the lungs ; in others the foramen ovale has not been closed, but a considerable VOL. LXXXVIII.] PHILOSOPHICAL TRANSACTIONS. 333 communication has remained between the 2 auricles; and in others there has been a communication between the 2 ventricles, from a deficiency in the septum. The effect of all these deviations is the same, on the blood in the general circulation, viz. that a part of the blood is not exposed to the air in the lungs; so that it is less pure as it circulates over the body. A more remarkable deviation in the struc- ture of the heart, than any to which I have just alluded, has been lately published by Dr. Baillie, in his Morbid Anatomy. In this heart, the aorta arose from the right ventricle, and the pulmonary artery from the left; the reverse of what ought, in the regular course of circulation, to have taken place; the veins being as usual; and no communication was found between the one vessel and the other, except through the remains of the ductus arteriosus, which was not larger than a crow quill, and a small part of the foramen ovale, which still continued open; yet this child lived for 2 months. In the following case of monstrous formation of the heart, there is this very great singularity, that nature seems to have substituted, very exactly, the circula- tion which takes place in some amphibious animals, for that which is natural to the human species. The infant had arrived at its full time, and lived 7 days after its birth. Instead of the usual integuments, muscles, &c» a membranous bag appeared to protrude oA the upper and fore part of the abdomen, extending from the last bone of the sternum some way below the middle of the belly, and out- wards, so as to be nearly circular: the navel-string seemed to enter this membrane near its middle, and to wind superficially, for some little way, towards the left side; it then dipped into the abdomen, at the place where this membrane joined the usual coverings. Within this bag, the appearance of which was very nearly similar to that of the chorion and amnios which envelope the foetus at birth, but thicker in consistence, a tumour was perceived, possessing considerable motion, from the nature of which, no doubt was entertained that it was the heart. During the short period of the child's life, it was seen and examined by a number of professional men. On its death, the tumour was carefully opened by Mr. Morell, in the presence of Dr. Poignand; when the heart, as was previously suspected, appeared to be situated in the epigastric region of the abdomen, and to be imbedded, as it were, in a cavity formed on the superior surface of the liver. In this state, the child was sent to Dr. Baillie, by whose desire I injected the heart, and laid its principal vessels bare, so as to bring their uncommon distribution and course into view: a preparation of them still remains in Dr, Baillie's possession. A considerable part of the tendinous portion of the diaphragm appeared to be wanting, as well as the lower part of the pericardium, which is usually affixed to it. The thorax being laid open on each side of the sternum, the 2 pleurae were seen passing from that bone to the spine, and covering the lungs as usual. The lungs appeared perfectly natural in colour, and nearly so in shape; but were larger and fuller than usual, in consequence of more room being afforded for them in the thorax, from the peculiar situation of the heart. In the space corresponding to 334 PHILOSOPHICAL TRANSACTIONS. [ANNO 17Q8. the anterior mediastinum, was the thymus gland, considerably longer than in other children, and extending downwards the whole length of the sternum ; behind this, was a peculiar arrangement of blood-vessels. The heart, instead of consisting of 4 cavities, as in the natural structure, con- sisted of a single auricle and ventricle, which were each of them large in their size. A large arterial trunk arose from the ventricle, and ascended into the thorax, be- tween the pleurae, immediately behind the thymus gland: it soon divided into 1 large branches, 1 of which continued to ascend, forming the aorta; the other passed backwards, and proved to be the pulmonary artery. The aorta, having reached the common place of its curvature, formed it in the same manner as it usually does; sent off the vessels belonging to the head and upper extremities; descended before the vertebrae, and passed into the abdomen between the crura of the diaphragm. From the place where it began to form the arch, it was in no respect different from the aorta of any other infant, except that no bronchial artery was sent to the lungs, from it or any of its ramifications. The vessel which proved to be the pulmonary artery, almost immediately divided into 2 branches; one going to the lungs of the left, the other to the lungs of the right side. On measuring accurately the circumference of the aorta, where it separated from the original trunk, it was found to be exactly 1^- inch. On measuring the circum- ference of the pulmonary artery, in the same manner, it was found to be -{-§- of an inch; so that it was -j^. of an inch less than the aorta. The vena cava inferior, having been partly surrounded by the substance of the liver, entered the lower and back part of the auricle. The subclavian vein of the right side crossed over to the left of the mediastinum, where it joined the left subclavian, and formed the vena cava superior. This passed down on the left of the ascend- ing, and before the descending part of the aorta; it was then joined by a trunk formed by 1 large veins, which came out of the lungs, and which were situated immediately behind the pulmonary arteries: the union of this trunk with the vena cava superior was continued into a large vessel, which gradually expanded itself into the auricle. The vena azygos ascended on the left side; received some branches which passed under the aorta from the right, and then entered the upper and back part of the vena cava superior: there were no bronchial veins. From there being neither bronchial arteries nor veins, it would appear that the pulmonary arteries and veins, in addition to their usual offices, performed those of the bron- chial vessels. The liver was not divided on its upper surface by the suspensory- ligament, but had a considerable cavity scooped, as it were, out of its substance; which in shape was adapted to, and contained the heart: it was also, in some other particulars, rather different from its natural shape, but not sufficiently so to re- quire being minutely described. The rest of the infant was not found to be dis- similar to any other. It is a well-ascertained fact, that the blood receives a florid hue from the influ- ence of the air on it in the lungs; and this change is supposed to be effected by VOL. LXXXVIII.] PHILOSOPHICAL TRANSACTIONS. 335 the combination of a certain quantity of oxygen gas with it. In passing from the arteries to the veins, in every part of the body except the lungs, it loses the florid hue, and becomes darker : the florid blood is that which is employed for the pur- poses of supporting life. In the natural circulation, it is well known that the whole of the blood conveyed to, and circulating in, the pulmonary artery, is of a dark colour; and the whole of it, when returned by the pulmonary veins, is florid. It is obvious, in the case which has been described, that there always must have been florid and dark-coloured blood, mixing and circulating in the arteries. It would seem also, on the first reflexion, that the quantity of dark-coloured blood would be the greatest, in the same proportion as the capacity of the aorta was larger than that of the pulmonary artery. It is therefore necessary to recollect, that a considerable proportion of the blood carried to the lungs was already florid or oxygenated; and also, that the lungs in this infant were larger in proportion, than in children of the same age: a smaller quantity of blood therefore was to be oxygenated, and a larger surface than usual was appropriated for this purpose. It appears also, from experiments, such as making a person breathe air in which there is a greater pro- portion of oxygen gas than in our atmosphere, that the blood can combine with more of it than it does in natural respiration : it therefore is not an improbable supposition, that a larger quantity was combined here. A small drawback must be allowed, for the quantity of oxygenated blood used in the support and secretions of the lungs, and which is usually conveyed to them by the bronchial artery; but this quantity is too small to require more than this slight observation of it. The blood also which passed to the lungs, must have been again conveyed to the heart sooner, from the shortness of its circuit; and must have entered the heart with a quicker or stronger current, than that blood which passed to, and was returned from, the more remote parts of the body; as, in this child, the pulmonary artery and aorta were filled by the contraction of the same ventricle. In the hearts of other children, some time after birth, the muscular fibres of the right side are much fewer in number than in the left. If these circumstances are admitted as fact, viz. that the blood circulating through the lungs of this child was combined with a larger proportion of oxygen gas, and was returned in a quicker and stronger current into the auricle than that returned by the venae cavae, it seems reasonable to infer, that this blood, mixing and blend- ing with the dark or unoxygenated blood, would render the whole nearly as much oxygenated as it usually is found in the left side of the heart, and in the aorta; therefore, that the blood circulating in the arteries of this child would be fully equal to the support of life. Previous to birth, this peculiarity of structure could not affect its health or growth, as the placenta then answers the purpose which the lungs do afterwards; and the single ventricle seemed as equal, from its size, to propel the blood on to the placenta, as both ventricles in the natural state are, by means of their communication through the ductus arteriosus.* * It is here not unworthy of remark, that the circulation in this child, after its birth, was in several 336 PHILOSOPHICAL TRANSACTIONS. £aNNO 1798. The inference which has been drawn seems further confirmed, from the colour and heat of this child, during life, being not perceptibly different from those of other children. In all those cases of malformation of the heart where the foramen ovale, or the ductus arteriosus, has continued open; or where the septum of the ventricles has been perforated, and the pulmonary artery small, and at the same time 2 ventricles, it has been observed, that the body had a livid colour, and in general that there was a deficiency of heat. From the particular inquiries which I made, concerning the heat and colour of this child, of the professional gentlemen who saw it during life, and of the nurse who attended and dressed it, I found that the heat, so far as could be judged by the feeling, for it was not tried by the ther- mometer, was in no respect different from that of other children ; and that the co- lour of the skin was perfectly natural, except that, on the day on which it was born, and a short period before its death, the lips occasionally had something of a livid appearance; but that this did not last any time, as they were generally pale. This occasional lividness would happen to a child in that state, should the heart and circulation be in no way different from what they naturally are. I could meet with no other remarkable circumstances, either in the history of the mother during pregnancy, or in the child after birth. It cried occasionally, like other children, but seemed weak, and in pain; it slept; it sucked heartily, even a few hours before its death, and had apparently healthy evacuations of urine and faeces. Its death can be satisfactorily accounted for, from another cause than the extraordinary formation of its heart and blood-vessels. The membranous covering on the fore part of the abdomen, did not appear to possess sufficient vascularity to retain its life after birth ; for it immediately lost its living principle, «nd became putrid and mouldy in parts. Previous to the child's death, a process of separation had begun, between it and the living parts to which it was connected, and a line of inflammation was distinctly seen. Had this process been completed, and the slough thrown off, the heart would have been exposed; but, before this, the heart itself had inflamed; which was proved from its being found covered with a coat of coagulable lymph recently thrown out, and from this inflammation its death must have arisen. * Had the heart been covered with the usual parietes of the abdomen, it is pro- bable, notwithstanding its situation, that this child might have lived in a tolerable state of health for years; but must constantly have been exposed to have its heart injured by some external accident, from its not being defended by the ribs and the sternum. The formation and disposition of the heart and vessels, in this child, circumstances similar to the circulation in other children previous to that period. A child, before birth, may be said to have a single heart j as both the auricles communicate together, by means of the foramen ovale ; and the pulmonary artery communicates with the aorta, by means of the ductus arteriosus. Hence, in the foetal heart, the blood returned from the body, which is of a dark colour, and the blood returned from the placenta, which is florid, are poured into the same auricle; the blood which is sent to the placenta is therefore already in part oxygenated. — Orig. VOL. LXXXVIII.] PHILOSOPHICAL TRANSACTIONS. 337 resemble much those which are found in the frog, and some other amphibious ani- mals; but this infant could not, like them, be amphibious. Those animals are extremely tenacious of life, so that they live some time, even after their heart and lungs are removed from their bodies; and as their circulation can go on without respiration, it is therefore not wonderful that they often live a considerable time without change of air. Life, in the human species, depends equally on both these actions; for death takes place, if either of them should stop. The circulation of the blood in this infant would have met with no impediment, had it been immersed in water; but, unless respiration went on, which in that state it could not do, the blood could undergo no change in the lungs; and this change is equally essential to the support of life, as the circulation of the blood. XIV. On a Singular Instance of Atmospherical Refraction. By Wm. Latham, Esq., F. R. &, and A. S. p. 357- July 2,6, about 5 o'clock in the afternoon, while sitting in my dining-room at this place, Hastings, which is situated on the Parade, close to the sea-shore, nearly fronting the south, my attention was excited by a great number of people running down to the sea side. On inquiring the reason, I was informed that the coast of France was plainly to be distinguished with the naked eye. I immediately went down to the shore, and was surprized to find that, even without the assistance of a telescope, I could very plainly see the cliffs on the opposite coast; which, at the nearest part, are between 40 and 50 miles distant, and are not to be discerned, from that low situation, by the aid of the best glasses. They appeared to be only a few miles off, and seemed to extend for some leagues along the coast. I pursued my walk along the shore to the eastward, close to the water's edge, conversing with the sailors and fishermen on the subject. At first they could not be persuaded of the reality of the appearance ; but they soon became so thoroughly convinced, by the cliffs gradually appearing more elevated, and approaching nearer, as it were, that they pointed out, and named to me, the different places they had been accustomed to visit; such as, the Bay, the Old Head or Man, the Windmill, &c. at Boulogne; St. Vallery, and other places on the coast of Picardy; which they afterwards con- firmed, when they viewed them through their telescopes. Their observations were, that the places appeared as near as if they were sailing, at a small distance, into the harbours. Having indulged my curiosity on the shore for near an hour, during which the cliffs appeared to be at some times more bright and near, at others more faint and at a greater distance, but never out of sight, I went on the eastern cliff or hill, which is of a very censiderable height, when a most beautiful scene presented itself to my view ; for I could at once see Dengeness, Dover cliffs, and the French coast, all along from Calais, Boulogne, &c. to St. Vallery; and, as some of the fishermen affirmed, as far to the westward even as Dieppe. By the telescope, the French fishing-boats were plainly to be seen at anchor; and the different colours of the VOL. XVIII. X x 338 PHILOSOPHICAL TRANSACTIONS. [ANNO 17Q8. land on the heights, with the buildings, were perfectly discernible. This curious phenomenon continued in the highest splendour till past 8 o'clock, though a black cloud totally obscured the face of the sun for some time, when it gradually vanished. I was assured, from every inquiry I could make, that so remarkable an instance of atmospherical refraction had never been witnessed by the oldest inhabitant of Hastings, nor by any of the numerous visitors come to the great annual fair. The day was extremely hot. I had no barometer with me, but suppose the mercury must have been high, as that and the 3 preceding days were remarkably fine and clear. To the best of my recollection, it was high water at Hastings about 2 o'clock p. m. Not a breath of wind was stirring the whole of the day; but the small pennons at the mast-heads of the fishing-boats in the harbour were in the morning at all points of the compass. I was, a few days afterwards, at Win- chelsea, and at several places along the coast; where I was informed, the above phenomenon had been equally visible. When I was on the eastern hill, the cape of land called Dengeness, which extends nearly 2 miles into the sea, and is about l6 miles distant from Hastings, in a right line, appeared as if quite close to it; as did the fishing-boats, and other vessels, which were sailing between the 2 places; they were likewise magnified to a great degree. XV. Of a Tumour found in the Substance of the Human Placenta. By John Clarke, M.D. p. 36 1. The structure of the egg of oviparous animals serves to elucidate the corres- ponding process in the viviparous ; and though in many cases analogies are very inconclusive, yet in this the resemblance is so close, that the latter may be said to be demonstrated by the former. A certain temperature, nourishment, and the ap- plication of vital air, or oxygen, seem to be essential to the evolution of the young of oviparous animals. As the young are expelled from the mother, contained in the cavity of the egg, at a very early period of their existence, and as afterwards they have no connection whatever with her, these are supplied by various contri- vances: and the mode of application has been very distinctly explained, by modern inquirers into the structure of eggs. Since then the same substances are to be produced, and supported, in viviparous as in oviparous animals, the conclusion is reasonable, that similai means should be employed to attain similar ends. It is easy to conceive how warmth may be imparted to a foetus situated in the uterus. The materials for nourishment, it receives from the placenta ; but the pre- cise manner in which they are supplied has not yet been discovered. Of the fact there can be no doubt, because there are many cases on record, in which there could be no other possible way by which support could be had. With respect to vital air, or oxygen, the young of all viviparous animals, while in the uterus, live in the same medium as fishes, and have a structure similar to gills, for the exposure of their blood to it; this structure is the placenta. The heart of the foetus is adapted to this mode of life, aad in effect consists but VOL. LXXXVIII.] PHILOSOPHICAL TRANSACTIONS. 33Q of 1 auricle and 1 ventricle, as it is found to do in fishes. The junction between the 2 ventricles is attended with a great advantage, in performing the circulation through the placenta; where the length and convolution of the umbilical vessels, in some animals, offer a great resistance to the force of the heart, and render more exertion necessary. In the superior aorta, the circulation is carried on by the left ventricle alone; as the ductus arteriosus does not join the aorta, till after the latter has given off the carotid and subclavian branches. Vital air is communicated to the blood of the embryo, as it is to the blood of fishes. This, in its passage through the gills, is exposed to water, which is allowed by all to contain a large proportion of vital or oxygen gas, and returns thence fitted to answer the purposes of life. In like manner, the blood of the mother, in the cells of the placenta, having received the essential part of this gas from her lungs, is applied to the capillary vessels of the umbilical arteries, which recei^ and transmit it to the embryo ; the life of which so entirely depends on this communication, that an obstruction to the circulation through the placenta, for 2 or 3 minutes, will sometimes irrecover- ably destroy it. The gills of fishes form a permanent part of their bodies, because they are designed to pass the whole of their lives in the same medium. This is not the case in the embryo of viviparous animals; which, after birth, is to change its situation for another, in which there is a direct exposure of the blood to atmospheric air. For this reason, the placenta, whose use is only temporary, is attached to the foetus by a slender connection, which is soon dissolved after birth. I have thought it necessary to introduce the foregoing observations on the structure and functions of the placenta, in order to show that the principal use of it is to transmit, and apply respectively to each other, the blood of the foetus, and that of its mo- ther. No other action is carried on by the vessels of the foetal portion of the pla- centa, as far as is yet known, than what has been described, unless so much as may be necessary for their own growth and nourishment. The tumour which gave occasion to this paper is however an instance to prove, that these vessels are capable, like those in other parts, of forming solid organized matter; and that very considerable deviations from the ordinary structure of the placenta may exist, and be perfectly compatible with the life and health of the foetus. Before the birth of a healthy child, an amazing quantity of liquor amnii was evacuated, which was by accident received in a vessel, and was found to amount to 2 gallons, Winchester measure. When the placenta came away, a hard solid body was found in its substance. It was preserved by Mr. Mainwaring, under whose care the case occurred, and was by him obligingly presented to me. Fine injection was thrown into the arteries and vein of the funis umbilicalis; when they were filled, they appeared to be enlarged thrice beyond their natural size. The placenta, thus prepared, was subjected to examination. Its anterior surface was found to be covered with the amnion, behind which lay the chorion as usual. Some branches, both of the arteries and veins, coming from the funis, ramified in the common manner, forming the foetal portion of the placenta. Others, of a very x x 2 340 PHILOSOPHICAL TRANSACTIONS. [ANNO 17Q8. large size, not less than a swan's quill, were sent to the tumour; which was situ- ated behind the chorion, and lay imbedded in the foetal portion of the placenta. The general form of this tumour was oval; about 44 inches long, and 3 inches broad; the thickness about 3 inches; and it weighed upwards of 7 oz. Its shape resembled that of a human kidney; 1 edge being almost uniformly convex, while the other, where the vessels approached it, was a little hollowed. The general cha- racter of the surface of the tumour was convexity; but in some parts of it there were slight indentations, more particularly in the course of the large vessels. The whole of the tumour was inclosed in a firm capsule, in the substance of which the large vessels were contained, nearly in the same manner as they are found in the dura mater. In the interstices of the vessels, the capsule did not appear to be vascular; at least there were no vessels capable of carrying the injected matter. The blood-vessels, branching off from the funis to supply the tumour, partly went over one side, and partly over the other side of the tumour; ramifying as they ran, till, meeting at the convex edge of the tumour, they anastomosed very freely. From the large trunks on the surface, small branches were given off, penetrating into the substance, and supplying the whole tumour with blood. On making a section through the tumour, in the direction of its length, the consistence was found to be uniform, firm, and fleshy, very much resembling, in this respect, the kidney. The cut surface, on examination, had somewhat of a mottled appearance; some parts being highly vascular, while others were white and uninjected. If the mere existence of such a tumour is not to be considered as a disease, there was no appearance of any morbid tendency in any part of it. The whole structure seemed to consist of a regularly organized matter throughout, supplied with vessels exclusively belonging to itself, and not passing to it from the surrounding parts, as is generally the case in diseased masses. Those who are inclined to consider every new appearance in the structure of parts as disease, may be disposed to include this under that appellation. But disease consists in such an alteration in the structure, or functions, of a part, as occasions the natural operations of it to be imperfectly performed, or entirely arrested. This tumour appears to have produced no such effect : all the common and known functions of the placenta were performed, not- withstanding the existence of this substance: the child had been as well nourished, and the benefits arising from the application of vital air or oxygen, to its blood, just as well supplied, as if the tumour had not existed. It cannot be said of this, as it might of some tumours, that it would in time have shown marks of a morbid tendency, so as to have deranged the common ac- tions of the placenta; because, when gestation terminates, the life, and all the uses of the placenta, are at an end. I am disposed, therefore, to consider this fleshy substance, as a solitary instance of a formative property in the vessels of the pla- centa; which they have not been hitherto generally known to possess.* * The placenta sometimes becomes converted into a mass of hydatids, connected to each other by small filaments j but this must be considered as a disease, inasmuch as the natural structure is destroyed, VOL. LXXXVIII.] PHILOSOPHICAL TRANSACTIONS. 341 There was a remarkable circumstance attending this case, which ought not to be lost sight of, viz. the extraordinary quantity of liquor amnii, which had been con- tained in the ovum. What connection there was between this and the tumour, cannot be absolutely explained from a single instance, as there did not seem to be any direct communication between the tumour and the cavity of the amnion. The whole of it lay, as has been before related, behind the chorion ; so that between it and the cavity of the ovum there were 2 membranes interposed. In its organi- zation, it had all the appearance of a glandular part, and was extremely vascular; but no duct could be found leading from it into the cavity of the ovum. Yet, though it may appear difficult to prove, that the quantity of liquor amnii depended on this substance, still, as it so considerably exceeded that which is found in com- mon, or has ever been described, it is reasonably to be believed that it did so. The manner however by which the secreted fluid was conveyed from the tumour into the general cavity of the ovum, must still remain unaccounted for. XVI. Qn the Roots of Equations. By James Woody B. D. p. 369. The great improvements in algebra, which modern writers have made, are chiefly to be ascribed to Vieta's discovery, that " every equation may have as many roots as it has dimensions." This principle was at first considered as extending only to positive roots; and even when it was found that the number might, in some cases, be made up by negative values of the unknown quantity, these were rejected as useless. It could not however long escape the penetration of the early writers on this subject, that in many equations, neither positive nor negative values could be discovered, which, when substituted for the unknown quantity, would cause the whole to vanish, or answer the condition of the question ; in such cases, the roots were said to be impossible, without much attention to their nature, or inquiry whether they admit of any algebraical representation or not. As far as the actual solution of equations was carried, viz. in cubics and biquadratics, the imaginary roots were found to be of this form, (a -f 4/ — Z>2); and subsequent writers, from this imperfect induction, concluded in general, that every equation has as many roots, of the form (a ± */ ±b2), as it has dimensions. In the present state of the science, this proposition is of considerable importance, and its truth ought to be established on surer grounds. The various transformations of equations, the dimen- sions to which they rise in their reduction, and the circumstances which attend their actual solution, are most easily explained, and most clearly understood by the help of this principle. Mr. Euler appears to have been the first writer who undertook to give a general proof of the proposition; but whatever may be thought of his reasoning in other respects, as he carries it no farther than to an equation of 4 dimensions, and it does not appear capable of being easily applied in other cases and it directly interferes with the offices of the placenta, which no longer performs perfectly the func- tions for which it was designed. Nourishment and vital air are no longer supplied properly to the fcfctus, which therefore commonly dies.— Orig. 342 PHILOSOPHICAL TRANSACTIONS. [ANNO 1798. it gives us no insight into the subject. Dr. Waring's observations on the propo- sition are extremely concise ; and, to common readers, it will still be a matter of doubt, whether a quantity of any description whatever will, when substituted for x in the expression x* — px* + qx6 — . . . . + w-> cause the whole to vanish. In the investigation of the proof here offered, it became necessary to attend to the method of finding the common measure of 2 algebraic expressions ; and to ob- serve particularly, in what manner new values of the indeterminate quantities am introduced; and how they may again be rejected. It appears, that these values are necessary in the division; and, when they have been thus introduced, they enter every term of the 2d remainder, from which they may be discarded. This circum- stance enables us, not only to determine the nature of the roots of every equation, but also affords a direct and easy method of reducing any number of equations to one, and obtaining the final equation in its lowest terms. Pbop. 1. To find a common measure of the quantities ax* -f- bxn~x + ex"'* -j- dxn's + &c. and a.*"-1 + bx*-* + cxn~s + d-z*"4 + &c. In order to avoid fractions, multiply every term of the dividend by a2, the square of the co-efficient of the first term of the divisor, and after finding 2 terms in the quotient, the remainder is (?) = (CA2 — Z>BA + GB2 — OCA) ff"~* + (tfA2 — Z>CA + GBC — ODA) X*-* -\~ &C. Let (ca — Z>b) a + (b2 — ca) a = «, (dA — be) a + (bc — da) a = (3, (eA — £d) a -f- (bd — ea) a = y, &c. and the first remainder (p) is a.x""% + |3ar"~3 + yx"~* + &c. proceed with this as a new divisor, and the next remainder (a) will be [(ca — Bj3) a + ((32 — ay) a] a?"-3 + [(Da — By) a -f (j3y — ai) a] Xn^ + &C. Respecting this operation we may observe: 1. That were not every term of the first dividend multiplied by a2, that quantity would be introduced by reducing the terms of the remainder (p) to a common denominator. 2. When p = O, Aa:""1 + ■Bxn~i -f cxn~3 + &c. is a divisor of a2 (axn + bxn~l + car"-4 + &c.) ; and therefore it is a divisor of axn + bxn~l -f- cxn~* + &c. unless it be a divisor of a2, which is impossible ; consequently no alteration is, in this case, made in the conclusion, by the introduction of a2. 3. When p does not vanish, then every divisor of p is a divisor of ax""1 -f- Bxn~* -f- cxn~s -f- &c. and of a2 (ax* + bxn~l -f- cr"-8 + &c.) ; and therefore of ax" -\- baf~l + cr"-9 -f- &c. unless a2 = O, in which case the remainder, p, becomes as (Ba"-9 -j- cx"~s -f- &c), every divisor of which is a divisor of B#n~* + car"""3 + &c. whether it be a divisor of ax" -f- bx"~l -j- cx"~* + &c. or not. That is, there are 2 values of the indeterminate quantity a, which, if retained, will produce erroneous con- clusions. 4. a2 enters every term of the 2d remainder (a), and the 2 values, before intro- duced, may therefore be again rejected. The co-efficient of the first term of this remainder is (ca — bj3) a -f ((32 — ay) . a ; and, by substituting for a, £ and y, VOL. LXXXVIII.] PHILOSOPHICAL TRANSACTIONS. 343 their values, and retaining only those terms in which a is not found, and those in which it is only of one dimension, we have ex = — £bca -f- acB2 — ac2A — Bj3 = -f- #BCA — acB2 + OBDA Cx — Bj3 = — «C2A + OBDA (Ca — Bj3) a = — a2B2C2A + a2B3DA (|32 — ay).A = a2B2C2A — 02B3DA; therefore, those parts of (cx — b|3) * + (PQ — ay) . a, in which a is of one dimen- sion, and in which it is not found, vanish. In the same manner it appears, that a2 enters every other term of the remainder may be 2 roots of this equation; then, as* = u2m ± 2mzu9W-1 + 2m . 2ot~X . z2*;7*-2 + &c. 1 ^srn-i _ ± p^«-i _L. (2»> — 1) . pZV*m~2 ± &C. I _- 0. 9af*»-* = ^?;3n-8 ± &c ( rxim-s= + &C.J 2m— 1 conseq. v2m + 2m . ^— - . z2 1 + z2"* + (2m - 1) . pz \ v^ + &c. * &£? T ? J + r2.2m-3 -f &c. = 0; also 344 PHILOSOPHICAL TRANSACTIONS. [ANNO 1798. 2m — 1 2m — 2 o izym_x + v = 0. Assume y = v2; and let the co-efficients of the terms of the former equation be 1, b, c, d} &c. and of the latter a, b, c, d, &c. then the equations become y» -J. ^y— « _L. Cym~* + c^™-3 -f &c. = 0, AT/"*-1 -f- B^m"J -f C2/m-3 -f &C. = 0. These equations have a common measure of the form y ± z, where z is expressed in terms of z and known quantities; and this common measure may be found, by dividing, as in prop. J, till y is exterminated, and making the last remainder equal to 0. Now, the first remainder is ((ca — Z>b) . A -f- b2 — ca) y""* + ((c?a — be) . a + bc — da) ym~s -J- ((eA — Z>d) . a + bd — ea) ym~* + &c ; or, by substitution, ayn-« _|_ fiym~i -+- yym~* + &c. and, in a, z rises to 6 dimensions; in (3, to 8 dimen- sions; and, in y, to 10 dimensions, &c. The 2d remainder is ((ex — Bj3) . x + (|32 — ay) . a) y»-3 -J- ((Da — By) . a -f- (j3y — aS) . a) z/m_4 -f &c. ; or, by substitu- tion, wA22/m-s -|- nA2ym~4 -f- &c. and, dividing by a2, the dimensions of z in m, are 15; in n, 17> &c. Let ?r, x, f, , = ± V ± z; therefore, by the solution of an equation of m . (2m — l) dimensions, 2 roots, z ± y' ± z> of the original equation, are discovered. Cor. 1 . Since 2 roots of the proposed equation are z -\- v, and z — v , a:2 — 2za: 4- z2 — f2 = O is a quadratic factor of that equation. Cor. 2. In the same manner that the 2 equations ym + by™"1 + cy1*-* + &c« = °> and Ay™-1 -f bj/'"-2 + cym~3 -f- &c. = O, are reduced to one, may any 2 equations be reduced to one, and one of the unknown quantities exterminated; also the con- clusion will be obtained in the lowest terms. Prop. 3. Every equation has as many roots, of the form a ± */ ± t>\ as it has dimensions. — Case 1. Every equation of an odd number of dimensions has, at least, one possible root; and it may therefore be depressed to an equation of an even number of dimensions. — Case 2. If the equation be of 2m dimensions, and m be TOL. LXXXVIII.] PHILOSOPHICAL TRANSACTIONS. 345 an odd number, then m . (2m — l) is an odd number, and consequently z and v2 (see prop, 2) have possible values ; therefore the proposed equation has a quadratic factor, x2 — 2zr + z2 — v2 = O, whose co-efficients are possible ; that is, it has 2 roots of the specified form; and it may be reduced 2 dimensions lower. Case 3. If m be evenly odd, or \m an odd number, then the equation for deter- mining z, has either 2 possible roots, or 2 of the form a ± by/ — 1, (case 2); and v2 will be of the form c ± dy/ — 1 ; hence one value of the quadratic factor x2 — 2-ux -f- z2 — v2 = O, will be of this form, x2 — (2a + 2b */ — l) x + ab + CD ^Z— i =0; and another of this form, x2 — (2a — 2b y/ — l) . x -{- ab — CD y'— l =0; consequently #4 — 4ar3 -j- (2ab + 4a2 + 4Z>2) x2 — (4oab -j- 4bcj))x -+• a2b2 + c2d2 = O, will be a factor of the proposed equation; and this biqua- dratic may be resolved into 2 quadratics, whose co-efficients are possible, and whose roots are therefore of the form specified in the proposition. In the same manner the proposition may be proved, when -fm, \mt -fem, &c. is an odd number; and thus it appears that it is true in all equations. Cor. 1 . If v2, or y, be positive, the roots of the quadratic fa'ctor x2 — 2z# + z2 — v2 = O, and therefore 2 roots of the proposed equation are possible. If y = O, 2 roots are equal ; and if y be negative, 2 roots are impossible. Cor. 2. If a possible value of z be determined, and substituted in b, c, d, &c. the original equation will have as many pairs of possible roots as there are changes of signs in the equation ym + by1""1 -j- cym~2 + &c. ss 0; and as many pairs of im- possible roots as there are continuations of the same sign. XVII. General Theorems, chiefly Porisms, in the Higher Geometry. By Hemy Brougham, Jun., Esq. p. 378. The following are a few propositions that have occurred to me, in the course of a considerable degree of attention which I have happened to bestow on that interesting, though difficult branch of speculative mathematics, the higher geo- metry. They are all in some degree connected ; the greater part refer to the conic hyperbola, as related to a variety of other curves. Almost the whole are of that kind called porisms, whose nature and origin is now well known ; and, if that ma- thematician to whom we owe the first distinct and popular account of this formerly mysterious, but most interesting subject,* should chance to peruse these pages, he will find in them additional proofs of the accuracy which characterizes his in- quiry into the discovery of this singularly beautiful species of proposition. Though each of the truths which I have here enunciated is of a very general and extensive nature, yet they are all discovered by the application of certain principles or properties still more general; and are thus only cases of propositions still more extensive. Into a detail of these I cannot at present enter: they compose a system of general methods, by which the discovery of propositions is effected with cer- * See Mr. Playfair's paper, in vol. 3 of the Edinburgh Trans. — Orig. VOL. XVIII, Y Y 346 PHILOSOPHICAL TRANSACTIONS. [ANNO 17Q8. tainty and case; and they are, very probably, in the doctrine of curve lines, what the ancients appear to have prized so much in plain geometry; though unfortunately all that remains to us of that treasure, is the knowledge of its high value. I have not added the demonstrations, which are all purely geometrical, granting the methods of tangents and quadratures : I have given an example, in the abridged synthesis, of what I consider as one of the most intricate. It is unnecessary to apolo- gize any further for the conciseness of this tract. Let it be remembered, that were each proposition followed by its analysis and composition, and the corollaries, scholia, limitations, and problems, immediately suggested by it, without any trouble on the reader's part, the whole would form a large volume, in the style of the ancient geometers ; containing the investigation of a series of connected truths, in one branch of the mathematics, all arising from varying the combinations of certain data enumerated in a general enunciation.* As a collection of curious general truths, of a nature, so far as I know, hitherto quite unknown, I am persuaded that this paper, with all its defects, may not be unacceptable to those who feel pleasure in contemplating the varied and beautiful relations between abstract quantities, the wonderful and extensive analogies which every step of our progress in the higher parts of geometry opens to our view. Prop. 1. Porism. PI. 5, fig. 10. — A conic hyperbola being given, a point may be found, such, that every straight line drawn from it to the curve, shall cut, in a given ratio, that part of a straight line passing through a given point which is in- tercepted between a point in the curve not given, but which may be found, and the ordinate to the point where the first mentioned line meets the curve. — Let x be the point to be found, na the line passing through the given point n, and m any point whatever in the curve ; join xm, and draw the ordinate mp ; then ac is to cp in a given ratio. Corol. This property suggests a very simple and accurate method of describing a conic hyperbola, and then finding its centre, asymptotes, and axes ; or, any of these being given, of finding the curve, and the remaining parts. Prop. 2. Porism. — A conic hyperbola being given, a point may be found, such, that if from it there be drawn straight lines to all the intersections of the given curve, with an infinite number of parabolas, or hyperbolas, of any given order what- ever, lying between straight lines, of which one passes through a given point, and the other may be found ; the straight lines so drawn, from the point found, shall be tangents to the parabolas, or hyperbolas. — This is in fact 2 propositions ; there being a construction for the case of parabolas, and another for that of hyperbolas. Prop. 3. Porism. — If, through any point whatever of a given ellipse, a straight line be drawn parallel to the conjugate axis, and cutting the ellipse in another point; and if at the first point a perpendicular be drawn to the parallel ; a point may be found, such, that if from it there be drawn straight lines, to the innumerable in- tersections of the ellipse with all the parabolas of orders not given, but which may • See the celebrated account of ancient geometrical works, in the 11th book of Pappus.— >Orig. VOL. LXXXVIII.] PHILOSOPHICAL TRANSACTIONS. 347 be found, lying between the lines drawn at right angles to each other, the lines so drawn from the point found, shall be normals to the parabolas at their intersections with the ellipse. Prop. 4. Porism. — A conic hyperbola being given, if through any point of it a straight line be drawn parallel to the transverse axis, and cutting the opposite hyperbolas, a point may be found, such, that if from it there be drawn straight lines, to the innumerable intersections of the given curve with all the hyperbolas of orders to be found, lying between straight lines which may be found, the straight lines so drawn shall be normals to the hyperbolas at the points of section. Scholium. The last 2 propositions give an instance of the many curious and ele- gant analogies between the hyperbola and ellipse ; failing however when, by equating the axes we change the ellipse into a circle. Prop. 5. Local theorem. Fig. 11. — If from a given point a, a straight line de move parallel to itself, and another cs, from a given point c, move along with it round c ; and a point i move along ab, from h, the middle point of ab, with a velocity equal to half the velocity of de ; then, if ap be always taken a 3d propor- tional to as and bc, and through p, with asymptotes d'e' and ab. a conic hyper- bola be described ; also with focus i and axis ab, a conic parabola be described ; then the radius vector from c to m, the intersection of the two curves, moving round c, shall describe a given ellipse. Prop. 6. Theorem. — A common logarithmic being given, and a point without it, a parabola, hyperbola, and ellipse, may be described, which shall intersect the logarithmic and each other in the same points ; the parabola shall cut the logarith- mic orthogonally ; and if straight lines be drawn from the given point to the common intersections of the 4 curves, these lines shall be normals to the lo- garithmic. Prop. 7. Porism. — Two points in a circle being given, but not in one diameter, another circle may be described, such, that if from any point of it to the given points straight lines be drawn, and a line touching the given circle, the tangent ehall be a mean proportional between the lines so inflected. Or, more generally, the square of the tangent shall have a given ratio to the rectangle under the in- flected lines. Prop. 8. Porism. Fig. 12. — Two straight lines ab, ap, not parallel, being given in position, a conic parabola mn may be found, such, that if, from any point of it m, a perpendicular mp be drawn to the one of the given lines nearest the curve, and this perpendicular be produced till it meets the other line in b ; and if from b a line be drawn to a given point c ; then mp shall have to pb together with cb, a given ratio. Scholium. This is a case of a most general enunciation, which gives rise to an infinite variety of the most curious porisms. Prop. 9. Porism. Fig. 13. — A conic hyperbola being given, a point may be Y Y 2 348 PHILOSOPHICAL TRANSACTIONS. [ANNO 17Q8. found, from which if straight lines be drawn to the intersections of the given curve with innumerable parabolas, or hyperbolas, of any given order whatever lying be- tween perpendiculars which meet in a given point, the lines so drawn shall cut, in a given ratio, all the areas of the parabolas or hyperbolas contained by the peripheries and co-ordinates to points of it, found by the innumerable intersections of another conic hyperbola, which may be found. — This comprehends evidently 2 propositions; one for the case of parabolas, the other for that of hyperbolas. In the former it is thus expressed with a figure. Let em be the given hyperbola ; ba, ac, the per- pendiculars meeting in a given point a : a point x may be found, such, that if xm be drawn to any intersection m of em with any parabola amn, of any given order whatever, and lying between ab and ac, xm shall cut, in a given ratio, the area amnp, contained by amn and ap, pn, co-ordinates to the conic hyperbola fn, which is to be found; thus, the area arm shall be to the area rmnp in a given ratio. Prop. 10. Porism. — A conic hyperbola being given, a point may be found, such, that if from it there be drawn straight lines, to the innumerable intersections of the given curve with all the straight lines drawn through a given point in one of the given asymptotes, the first mentioned lines shall cut, in a given ratio, the areas of all the triangles whose bases and altitudes are the co-ordinates to a 2d conic hyper- bola, which may be found, at the points where it cuts the lines drawn from the given point. Prop. 11. Porism. — A conic hyperbola being given, a straight line may be found, such, that if another move along it in a given angle, and pass through the inter- sections of the curve with all the parabolas, or hyperbolas, of any given order what- ever, lying between straight lines to be found, the moving line shall cut, in a given ratio, the areas of the curves described, contained by the peripheries and co- ordinates to another cpnic hyperbola, that may be found, at the points where this cuts the curves described. Prop. 12. Porism. — A conic hyperbola being given, a straight line may be found, along which if another move in a given angle, and pass through any point whatever of the hyperbola, and if this point of section be joined with another that may be found, the moving line shall cut, in a given ratio, the triangles whose bases and altitudes are the co-ordinates to a conic hyperbola, which may be found, at the points where it meets the lines drawn from the point found. Scholium, I proceed to give 1 or 2 examples, wherein areas are cut in a given ratio, not by straight lines, but by curves. Prop. 13. Porism. Fig. 14. — A conic hyperbola being given, if through any of its innumerable intersections with all the parabolas of any order, lying between straight lines, of which one is an asymptote, and the other may be found; an hyperbola of any order be described, except the conic, from a given origin in the given asymptote perpendicular to the axis of the parabolas, the hyperbola thus de- scribed shall cut, in a given ratio, an area, of the parabolas, which may be always found. VOL. LXXXVIII.] PHILOSOPHICAL TRANSACTIONS. 340, If from g, as origin, in ab, one of lm's asymptotes, there be described an hyper- bola ic', of any order whatever, except the first, and passing through m, a point where lm cuts any of the parabolas am, of any order whatever, drawn from a a point to be found, and lying between ab and ac, an area acd may be always found, (that is, for every case of am and ic',) which shall be constantly cut by ic', in the given ratio of m : n ; that is, the area amn : nmdc :: m : n. I omit the analysis* which leads to the following construction and composition. Constr. Let m 4- n be the order of the parabolas, and p -f q that of the hyper- bolas. Find

) X acd + q . an X ag = ap X (mp X (/> + ((M+«)x(g-g))+ Q)> From these equals take ^ . ag X an, and there remains — - — x {q — p) x acd equal to ap X pm X ( (W> + ,"* + Jlf """ ^ r P) + ?.ag X (ap - an) ; or, dividing by q - p, ^ X acd = ap X (-^±^) + -E-) X pm + ^4- X ag X (ap — an). Now, m " X ap X pm is equal to the area apm ; there- fore the area apm together with ~ X ap . pm, and — ~- X ag X (ap ~ an), or apm with — - — X ap . pm — X ag X (an — ap), or apm -\ ^— x ap . q — p q-p v 9-P pm £— x rect. pt, is equal to — — — X acd. Now ic' is an hyperbola of the order/) + q; therefore its area is ■ X rect. gh . mh. But q is greater than p; therefore — — is neerative, and *LlH?L js the area mhkc'; and the r p -q & q-p area ntkc' is equal to — - — X gt X tn ; therefore mnth is equal to (mhkc' — ntkc'), or to -—— X (gh . mh — gt . tn). From these equals take the com- mon rectangle at, and there remains the area mpn, equal to -— — X ap x mp — —2— X pt ; which was before demonstrated to be, together with apm, equal to q -. p — — — . acd. Therefore mpn, together with apm, that is, the area amn, is equal to — — - . acd ; consequently amn : acd : : m : m + N J ana< (dividendo) amn : nmdc :: m : n. An area has therefore been found, which the hyperbola ic' always cuts in a given ratio. Therefore, a conic hyperbola being given, &c. a. e. d. Scholium. This proposition points out, in a very striking manner, the connection between all parabolas and hyperbolas, and their common connection with the conic hyperbola. The demonstration here given is much abridged ; and, to avoid cir- cumlocution, algebraic symbols, and even ideas, have been introduced : but by at- tending to the several steps, any one will easily perceive that it may be translated into geometrical language, and conducted on purely geometrical principles, if any numbers be substituted for m, n, p, and q ; or if these letters be made representa- tives of lines, and if conciseness be less rigidly studied. Prop. 14. Theorem. — A common logarithmic being given; if from a given point, as origin, a parabola, or hyperbola, of any order whatever be described, cutting in VOL. LXXXVIII J PHILOSOPHICAL TRANSACTIONS. 351 a given ratio a given area of the logarithmic ; the point where this curve meets the logarithmic is always situated in a conic hyperbola, which may be found. Scholium. This proposition is, properly speaking, neither a porism, a theorem, nor a problem. It is not a theorem, because something is left to be found, or, as Pappus expresses it, there is a deficiency in the hypothesis : neither is it a porism; for the theorem, from which the deficiency distinguishes it, is not local. Prop. 15. Porism. Fig. 15. — A conic hyperbola being given ; 2 points may be found, from which if straight lines be inflected, to the innumerable intersections of the given curve with parabolas or hyperbolas, of any given order whatever, described between given straight lines ; and if co-ordinates be drawn to the inter- sections of these curves with another conic hyperbola, which may be found ; the lines inflected shall always cut off areas that have to one another a given ratio, from the areas contained by the co-ordinates. — Let x and y be the points found ; hd the given hyperbola, fe the one to be found ; adc one of the curves lying between ab and ag, intersecting hd and fe ; join xd, yd ; then the area a yd : xdcb in a given ratio. Prop. 16. Porism. Fig. 16. — If between 2 straight lines making a right angle, an infinite number of parabolas of any order whatever be described ; a conic para- bola may be drawn, such, that if tangents be drawn to it at its intersections with the given curves, these tangents shall always cut, in a given ratio, the areas con- tained by the given curves, the curve found, and the axis of the given curves. — Let amn be one of the given parabolas ; dmo the parabola found, and tm its tangent at m : atm shall have to tmr a given ratio. Prop. 17. Porism. — A parabola of any order being given ; 2 straight lines may be found, between which if innumerable hyperbolas of any order be described; the areas cut off" by the hyperbolas and the given parabola at their intersections, shall be divided, in a given ratio, by the tangents to the given curve at the inter- sections ; and conversely, if the hyperbolas be given, a parabola may be found, &c. &c. Prop. 18. Porism. — A parabola of any order (m -{■ n) being given, another of an order (m + In) may be found, such, that the rectangle under its ordinate and a given line, shall have always a given ratio to the area (of the given curve) whose abscissa bears to that of the curve found a given ratio. Example. Let m = 1, n = 1, and let the given ratios be those of equality ; the proposition is this ; a conic parabola being given, a semi-cubic one may be found, such, that the rectangle under its ordinate and a given line, shall be always equal to the area of the given conic parabola, at equal abscissae. Scholium. A similar general proposition may be enunciated and exemplified, with respect to hyperbolas ; and as these are only cases of a proposition applying to all curves whatever, I shall take this opportunity of introducing a very simple, and I think perfectly conclusive demonstration, of the 28th lemma, Principia, book i. " that no oval can be squared." It is well known, that the demonstration 352 PHILOSOPHICAL TRANSACTIONS. [ANNO 1798. which Sir Isaac Newton gives of this lemma, is not a little intricate ; and, whether from this difficulty, or from some real imperfection, or from a very natural wish not to believe that the most celebrated desideratum in geometry must for ever re- main a desideratum, certain it is, that many have been inclined to call in question the conclusiveness of that proof. Let amc be any curve whatever, (fig. 17,) and d a given line ; take in ab a part ap, having to ap a given ratio, and erect a perpendicular pm, such, that the rect- angle pm . d shall have to the area apm a given ratio ; it is evident that m will describe a curve amc, which can never cut the axis, unless in a. Now because pm is proportional to — -, or to apm, pm will always increase ad infinitum, if amc is infinite ; but if amc stops or returns into itself, that is, if it is an oval, pm is a maximum at b, the point of ab corresponding to b in ab ; consequently the curve amc stops short, and is irrational. Therefore pm, its ordinate, has not a finite re- lation to ap, its abscissa ; but ap has a given ratio to ap ; therefore pm has not a finite relation to ap, and apm has a given ratio to pm ; therefore it has not a finite relation to ap, that is, apm cannot be found in finite terms of ap, or is incom- mensurate with ap ; therefore the curve amb cannot be squared. Now amb is any oval ; therefore no oval can be squared. By an argment of precisely the same kind, it may be proved, that the rectification, also, of every oval is impossible. Therefore, &c. b ,, ,. y , x ab m v< ^^0 Multiply both numerator and denominator of the first and last terms by a ; then will - X T X arc v. s. x + —— X - •(«*- a?) -> f (a?- c) as - X TX 4 av 72v 7a4M+N X arc 900. Now the fluxion of an arc whose versed sine is x and radius -, is 2 equal to -r. which is also the fluxion of the arc whose sine is */ - and 1 2 -v/(ajt — * ) radius unity; therefore - X (— X arc sin \/- -\ X V (ax — x2\) — ■¥ J av4 a 4 v 7/2 (o: — c) is equal to - XrX — — — X arc 9O0 ; and, by the quadrature of the circle, — - x arc sin. */ — | ^— X \/(ax — x2), is the area whose abscissa is 4 a 4 v " x ; consequently the semicircle's area is — X arc 900. But the areas of ellipses are to the corresponding areas of the circles described on their transverse axes, as h nP1 x Qx — ■ cl the conjugate to the transverse ; therefore - X (— X arc sin. \/ — | — X */ (ax — x2)) is the area whose abscissa is x, of a semi-ellipse, whose axes are a and b ; and consequently - X — X arc 9O0 is the area of the semi-ellipse. There- fore the area apm — — (x — c) is equal to — ■ — of amfb. But ~ (x — c) = -^ x 2X ' ~ m+n 2V y2 (ap — ac) = —- X pc, is the triangle cpm ; consequently, apm — cpm, or acm, si is equal to X amfb ; and acm : amfb :: m : m + n ; or (dividendo) acm : n M + N • \ / cmfb :: m : n ; and the area of the ellipse is cut in a given ratio by the line drawn through the focus, a. e. d. vol. xviii. Z z 354 PHILOSOPHICAL TRANSACTIONS. [ANNO \7Q8 . Of this solution it may be remarked, that it does not assume as a postulate the description of the cycloid ; but gives a simple construction of that curve, flowing from a curious property, by which it is related to a given circle. This cycloid too gives, by its intersection with the ellipse, the point required, directly, and not by a subsequent construction, as Sir I. Newton's does. I was induced to give the de- monstration, from a conviction that it is a good instance of the superiority of mo- dern over ancient analysis ; and in itself perhaps no inelegant specimen of algebraic demonstration. Prop. 21. Problem. Fig. 20. — To find the curve whose tangent is always of the same magnitude. Analysis. Let mn be the curve required, ab the given axis, sm a tangent at any point m, and let d be the given magnitude ; then, sm . q . = sp . q . -f- pm . q. = cP; or> f + St = and y = ^r^ J therefore, i = ^X V(P - y2). In order to integrate this equation, divide - ^(d? — y*) into its 2 parts, - — -— ^ — - and — 'ZM ■ ; to find the fluent of the former. V(* - y1) a (1 + ) *y fi * y2 y* W - y1) ' d + V(d*-f) d x fluxion of = d+W-fa 1 therefore the fluent of -yV(ff_y) is - d X hyp. log. ** + V(<*'-ya)^ and the fluent of the other partj yy [s + V (d2 — y*); therefore the fluent of the aggregate - y/{tf — y2), is /(^ - /) - rf X h. 1. l±-£(*^2, or V (# -/)+^Xh. 1. rf + -^A _ ; a final equation to the curve required, a. e. i. I shall throw together, in a few corollaries, the most remarkable things that have occurred to me concerning this curve. Corol. 1. The subtangent of this curve is 0 0 „ 6 of their weight, it is plain that a very minute disturbing force will be sufficient to destroy the success of the experiment; and from the following experi- ments it will appear, that the disturbing force most difficult to guard against, is that arising from the variations of heat and cold ; for if one side of the case be warmer than the other, the air in contact with it will be rarefied, and in conse- quence will ascend, while that on the other side will descend, and produce a cur- rent which will draw the arm sensibly aside.-)- As I was convinced of the necessity of guarding against this source of error, I resolved to place the apparatus in a room which should remain constantly shut, and to observe the motion of the arm from without, by means of a telescope; and to suspend the leaden weights in such manner, that I could move them without entering into the room. This difference in the manner of observing, rendered it necessary to make some alteration in Mr. Michell's apparatus; and as there were some parts of it which I thought not so convenient as could be wished, I chose to make the greatest part of it anew. Fig. 1, pi. 7, is a longitudinal vertical section through the instrument, and the building in which it is placed : abcddcbaeffe is the case ; x and x are the two balls, which are suspended by the wires hx from the arm ghmh, which is itself suspended by the slender wire gl. This arm consists of a slender deal rod hmh, strengthened by a silver wire hgh ; by which means it is made strong enough to support the balls, though very light. f The case is supported, and set horizontal, by 4 screws, resting on posts fixed firmly into the ground : 2 of them are repre- sented in the figure, by s and s ; the other 2 are not represented, to avoid confusion. * Mr. Coulomb has, in a variety of cases, used a contrivance of this kind for trying small attrac- tions ; but Mr. Michell informed me of his intention of making this experiment, and of the method he intended to use, before the publication of any of Mr. Coulomb's experiments. — Orig. -j- M. Cassini, in observing the variation compass placed by him in the observatory, (which was con-. structed so as to make very minute changes of position visible, and in which the needle was suspended by a silk thread), found that standing near the box, in order to observe, drew the needle sensibly aside ; which I have no doubt was caused by this current of air. It must be observed,- that his com- pass-box was of metal, which transmits heat faster than wood, and also was many inches deep ; both which causes served to increase the current of air. To diminish the effect of this current, it is by all means advisable to make the box, in which the needle plays, not much deeper than is necessary to pre- vent the needle from striking against the top and bottom. — Orig. J Mr. Michell's rod was entirely of wood, and was much stronger and stiffer than this, though not much heavier ; but, as it had warped when it came to me, I chose to make another, and preferred this form, partly as being easier to construct and meeting with less resistance from the air, and partly because, from its being of a less complicated form, I could more easily compute how much it was attracted by the weights. — Orig. 390 PHILOSOPHICAL TRANSACTIONS. [ANNO 17Q8. gg and gg are the end walls of the building, w and w are the leaden weights; which are suspended by the copper rods RrprR, and the wooden bar rr, from the centre pin pjb. This pin passes through a hole in the beam hh, perpendicularly over the centre of the instrument, and turns round in it, being prevented from falling by the plate/), mm is a pulley, fastened to this pin; and Mm a cord wound round the pulley, and passing through the end wall ; by which the observer may turn it round, and so move the weights from one situation to the other. Fig. 1 is a plan of the instrument, aaaa is the case ; ssss the 4 screws for supporting it ; h h the arm and balls , w and w the weights; mn, the pulley for moving them. When the weights are in this position, both conspire in drawing the arm in the direction hw ; but, when they are removed to the situation w and w, represented by the dotted lines, both conspire in drawing the arm in the con- trary direction hw. These weights are prevented from striking the instrument, by pieces of wood, which stop them as soon as they come within ± of an inch of the case. The pieces of wood are fastened to the wall of the building ; and I find that the weights may strike against them with considerable force, without sensibly shaking the instrument. In order to determine the situation of the arm, slips of ivory are placed within the case, as near to each end of the arm as can be done without danger of touch- ing it, and are divided to 20ths of an inch. Another small slip of ivory is placed at each end of the arm, serving as a vernier, and subdividing these divisions into 5 parts ; so that the position of the arm may be observed with ease to lOOths of an inch, and may be estimated to less. These divisions are viewed, by means of the short telescopes t and t, fig. 1, through slits cut in the end of the case, and stopped with glass ; they are enlightened by the lamps l and l, with convex glasses, placed so as to throw the light on the divisions ; no other light being admitted into the room. The divisions on the slips of ivory run in the direction ww, fig. 2, so that, when the weights are placed in the positions w and w, repre- sented by the dotted circles, the arm is drawn aside, in such direction as to make the index point to a higher number on the slips of ivory ; for which reason, I call this the positive position of the weights. fk, fig. 1, is a wooden rod, which, by means of an endless screw, turns round the support to which the wire gl is fastened, and so enables the observer to turn round the wire, till the arm settles in the middle of the case, without danger of touching either side. The wire gl is fastened to its support at top, and to the centre of the arm at bottom, by brass clips, in which it is pinched by screws. In these 2 figures, the different parts are drawn nearly in the proper proportion to each other. Before proceeding to the account of the experiments, it will be proper to say something of the manner of observing. Suppose the arm to be at rest, and its position to be observed, let the weights be then moved, the arm will not only be thus drawn aside, but it will be made to vibrate, and its vibrations will continue a VOL. LXXXVHI.] PHILOSOPHICAL TRANSACTIONS. 3Q1 great while; so that, in order to determine how much the arm is drawn aside, it is necessary to observe the extreme points of the vibrations, and thence to deter- mine the point which it would rest at if its motion was destroyed, or the point of rest, as I shall call it. To do this, I observe 3 successive extreme points of a vibration, and take the mean between the 1st and 3d of these points, as the ex- treme point of vibration in one direction, and then assume the mean between this and the 2d extreme, as the point of rest; for, as the vibrations are continually diminishing, it is evident that the mean between 2 extreme points will not give the true point of rest. It may be thought more exact, to observe many extreme points of vibration, so as to find the point of rest by difFerent sets of 3 extremes, and to take the mean result; but it must be observed, that notwithstanding the pains taken to prevent any disturbing force, the arm will seldom remain perfectly at rest for an hour together; for which reason, it is best to determine the point of rest, from observations made as soon after the motion of the weights as possible. The next thing to be determined is the time of vibration, which is found in this manner: I observe the 2 extreme points of a vibration, and also the times at which the arm arrives at 2 given divisions between these extremes, taking care, as well as I can guess, that these divisions shall be on difFerent sides of the middle point, and not very far from it. I then compute the middle point of the vibra- tion, and by proportion find the time at which the arm comes to this middle point. I then, after a number of vibrations, repeat this operation, and divide the interval of time, between the coming of the arm to these 2 middle points, by the number of vibrations, which gives the time of 1 vibration. To judge of the propriety of this method, we must consider in what manner the vibration is affected by the resistance of the air, and by the motion of the point of rest. Let the arm, during the first vibration, move from d to b, fig. 3, and during the 2d from b to d; bg? being less than db, on account of the resistance. Bisect db in m, and Bd in m} and bisect Mm in n, and let x be any point in the vibration; then if the resistance is proportional to the square of the velocity, the whole time ©f a vibration is very little altered; but, if t is taken to the time of one vibration, as the diameter of a circle to its semi-circumference, the time of moving from b to n exceeds -i- a vibration, by — nearly; and the time of moving from b to m falls short of 4- a vibration, by as much; and the time of moving from b to x, in the 2d vibration, exceeds that of moving from x to b, in the first, by - — ■ -„ supposing ad to be bisected in $; so that, if a mean is taken, between the time of the first arrival of the arm at x and its returning back to the same point, this mean will be earlier than the true time of its coming: to b, by — „. & ' J 8b»2 */bx x x$ The effect of motion in the point of rest is, that when the 'arm is moving in the same direction as the point of rest, the time of moving from one extreme point of vibration to the other is increased, and it is diminished when they are moving 3Q2 PHILOSOPHICAL TRANSACTIONS. [ANNO 1 7Q8. in contrary directions; but if the point of rest move uniformly, the time of moving from one extreme to the middle point of the vibration, will be equal to that of moving from the middle point to the other extreme, and also, the time of 1 suc- cessive vibrations will be very little altered ; and therefore the time of moving from the middle point of one vibration to the middle point of the next, will also be very little altered. It appears therefore, that on account of the resistance of the air, the time at which the arm comes to the middle point of the vibration, is not ex- actly the mean between the times of its coming to the extreme points, which causes some inaccuracy in my method of finding the time of a vibration. It must be ob- served however, that as the time of coming to the middle point is before the middle of the vibration, both in the first and last vibration, and in general is nearly equally so, the error produced from this cause must be inconsiderable; and, on the whole, I see no method of finding the time of a vibration which is liable to less objection. The time of a vibration may be determined, either by previous trials, or it may be done at each experiment, by ascertaining the time of the vibrations which the arm is actually put into by the motion of the weights; but there is one advantage in the latter method, namely, that if there should be any accidental attraction, such as electricity, in the glass plates through which the motion of the arm is seen, which should increase the force necessary to draw the arm aside, it would also dimi- nish the time of vibration ; and consequently the error in the result would be much less, when the force required to draw the arm aside was deduced from experiments made at the time, than when it was taken from previous experiments. Account of the Experiments. — In the first experiments, the wire by which the arm was suspended was 394- inches long, and was of copper silvered, one foot of which weighed 2Tv grains: its stiffness was such, as to make the arm perform a vibration in about 15 minutes. I immediately found indeed that it was not stiff enough, as the attraction of the weights drew the balls so much aside, as to make them touch the sides of the case; I chose however to make some experiments with it before I changed it. In this trial, the rods by which the leaden weights were sus- pended were of iron; for, as I had taken care that there should be nothing mag- netical in the arm, it seemed of no signification whether the rods were magnetical or not; but, for greater security, I took off the leaden weights, and tried what effect the rods would have by themselves. Now I find, by computation, that the attraction of gravity of these rods on the balls, is to that of the weights, nearly as 17 to 2500; so that, as the attraction of the weights appeared, by the foregoing trial, to be sufficient to draw the arm aside by about 1 5 divisions, the attraction of the rods alone should draw it aside about -^ of a division; and therefore the motion of the rods from one near position to the other, should move it about | of a division. The result of the experiment was, that for the first 15 minutes after the rods were removed from one near position to the other, very little motion was produced in the arm, and hardly more than ought to be produced by the action of gravity; TOL. LXXXVIII.] PHILOSOPHICAL TRANSACTIONS. 3g3 but the motion then increased, so that, in about a quarter or half an hour more, it was found to have moved 4. or 14- division, in the same direction that it ought to have done by the action of gravity. On returning the irons back to their former position, the arm moved backward, in the same manner that it before moved for- ward. It must be observed, that the motion of the arm, in these experiments was hardly more than would sometimes take place without any apparent cause; but yet, as in 3 experiments which were made with these rods, the motion was constantly of the same kind, though differing in quantity from 4 to 14. division, there seems great reason to think that it was produced by the rods. As this effect seemed to be owing to magnetism, though it was not such as I should have expected from that cause, I changed the iron rods for copper, and tried them as before; the result was, that there still seemed to be some effect of the same kind, but more irregular, so that I attributed it to some accidental cause, and therefore hung on the leaden weights, and proceeded with the experiments. It must be observed, that the effect which seemed to be produced by moving the iron rods from one near position to the other, was, at a medium, not more than one division ; whereas the effect produced by moving the weight from the midway to the near position, was about ] 5 divi- sions; so that, if I had continued to use the iron rods, the error in the result thus caused, could hardly have exceeded -3V of the whole. In exper. 1, Aug. 5, the motions of the weights between the midway and posi- tive positions were thus: Motion on moving from midway to positive = 14.32 From positive to midway = 14.1 Time of one vibration =± 14m 55s. It must be observed, that in this experiment, the attraction of the weights drew the arm from 11.5 to 25.8, so that, if no contrivance had been used to prevent it, the momentum thus acquired would have carried it to near 40, and would there- fore have made the balls strike against the case. To prevent this, after the arm had moved near 15 divisions, I returned the weights to the midway position, and let them remain there, till the arm came nearly to the extent of its vibration, and then again moved them to the positive position, by which the vibrations were so much diminished, that the balls did not touch the sides ; and it was this which pre- vented my observing the first extremity of the vibration. A like method was used when the weights were returned to the midway position, and in the 2 following ex- periments. The vibrations, in moving the weights from the midway to the positive position were so small, that it was thought not worth while to observe the time of the vibration. When the weights were returned to the midway position, I deter- mined the time of the arm's coming to the middle point of each vibration, in order to see how nearly the times of the different vibrations agreed together. In great part of the following experiments, I contented myself with observing the time of its coming to the middle point of only the first and last vibration. vol. xviii 3 E 3Q4 PHILOSOPHICAL TRANSACTIONS. [ANNO 1798. In the 2d experiment, Aug. 6, in like manner, the time of 1 vibration was 14m 42s; and in the 3d experiment, Aug. 7, it was 14m 46s. These experiments are sufficient to show, that the attraction of the weights on the balls is very sensible, and are also sufficiently regular to determine the quantity of this attraction pretty nearly, as the extreme results do not differ from each other by more than ~ Part« But there is a circumstance in them, the reason of which does not readily appear, namely, that the effect of the attraction seems to increase, for half an hour, or an hour, after the motion of the weights; as in all the 3 expe- riments, the mean position kept increasing for that time, after moving the weights to the positive position ; and kept decreasing, after moving them from the positive to the midway position. The first cause which occurred to me was, that possibly there might be a want of elasticity, either in the suspending wire, or something it was fastened to, which might make it yield more to a given pressure, after a long continuance of that pressure, than it did at first. To put this to the trial, I moved the index so much, that the arm, if not prevented by the sides of the case, would have stood at above 50 divisions, so that, as it could not move farther than to 35 divisions, it was kept in a position 15 divisions distant from that which it would na- turally have assumed from the stiffness of the wire; or, in other words, the wire was twisted 1 5 divisions. After having remained 2 or 3 hours in this position, the index was moved back, so as to leave the arm at liberty to assume its natural position. It must be observed, that if a wire is twisted only a little more than its elasticity admits of, then, instead of setting, as it is called, or acquiring a permanent twist all at once, it sets gradually, and when left at liberty it gradually loses part of that set which it acquired ; so that if, in this experiment, the wire, by having been kept twisted for 2 or 3 hours, had gradually yielded to this pressure, or had begun to set, it would gradually restore itself, when left at liberty, and the point of rest would gradually move backwards: but though the experiment was twice repeated, I could not perceive any such effect. The arm was next suspended by a stiffer wire : after which, in the next 2 expe- riments, being the 4th and 5th, the times of vibration were thus: viz. 7m2sand7m 58. In the 4th experiment, the effect of the weights seemed to increase on standing, in all the 3 motions of the weights, conformably to what was observed with the former wire ; but in the last experiment the case was different ; for though, on moving the weights from positive to negative, the effect seemed to increase on standing, yet on moving them from negative to positive, it diminished. My next trials were, to see whether this effect was owing to magnetism. Now, as it happened, the case in which the arm was inclosed, was placed nearly parallel to the magnetic east and west, and therefore, if there was any thing magnetic in the balls and weights, the balls would acquire polarity from the earth ; and the weights also, after having remained some time, either in the positive or negative VOL. LXXXVIII.] PHILOSOPHICAL TRANSACTIONS. 3Q5 position, would acquire polarity in the same direction, and would attract the balls ; but when the weights were moved to the contrary position, that pole which before pointed to the north, would point to the south, and would repell the ball it was approached to ; but yet, as repelling one ball towards the south has the same effect on the arm as attracting the other towards the north, this would have no effect on the position of the arm. After some time however, the poles of the weight would be reversed, and would begin to attract the balls, and would therefore produce the same kind of effect as was actually observed. To try whether this was the case, I detached the weights from the upper part of the copper rods by which they were suspended, but still retained the lower joint, namely, that which passed through them ; I then fixed them in their positive po- sition, in such manner, that they could turn round on this joint, as a vertical axis. I also made an apparatus, by which I could turn them half way round, on these vertical axes, without opening the door of the room. Having suffered the appa- ratus to remain in this manner for a day, I next morning observed the arm, and having found it to be stationary, turned the weights half way round on their axes, but could not perceive any motion in the arm. Having suffered the weights to remain in this position for about an hour, I turned them back into their former position, but without its having any effect on the arm. This experiment was re- peated on 2 other days, with the same result. We may be sure, therefore, that the effect in question could not be produced by magnetism in the weights ; for if it was, turning them half round on their axes would immediately have changed their magnetic attraction into repulsion, and have produced a motion in the arm. As a further proof of this, I took off the leaden weights, and in their room placed two 10-inch magnets ; the apparatus for turning them round being left as it was, and the magnets being placed horizontal, and pointing to the balls, and with their north poles turned to the north ; but I could not find that any alteration was pro- duced in the place of the arm, by turning them half round : which not only confirms the deduction drawn from the former experiment, but also seems to show, that in the experiments with the iron rods, the effect produced could not be owing to magnetism. The next thing which suggested itself to me was, that possibly the effect might be owing to a difference of temperature between the weights and the case ; for it is evident, that if the weights were much warmer than the case, they would warm that side which was next to them, and produce a current of air, which would make the balls approach nearer to the weights. Though I thought it not likely that there should be sufficient difference, between the heat of the weights and case, to have any sensible effect, and though it seemed improbable that, in all the fore- going experiments, the weights should happen to be warmer than the case, I re- solved to examine into it, and for this purpose removed the apparatus used in the last experiments, and supported the weights by the copper rods, as before ; and 3 E 2 396 PHILOSOPHICAL TRANSACTIONS. [ANNO 1798. having placed them in the midway position, I put a lamp under each, and placed a thermometer with its ball close to the outside of the case, near that part which one of the weights approached to in its positive position, and in such manner that I could distinguish the divisions by the telescope. Having done this, I shut the door, and some time after moved the weights to the positive position. At first, the arm was drawn aside only in its usual manner ; but in half an hour the effect was so much increased, that the arm was drawn 14 divisions aside, instead of about 3, as it would otherwise have been, and the thermometer was raised near 140 ; namely, from 6)° to 624-0. On opening the door, the weights were found to be no more heated, than just to prevent their feeling cool to my fingers. As the effect of a difference of temperature appeared to be so great, I bored a small hole in one of the weights, about -§• of an inch deep, and inserted the ball of a small thermometer, and then covered up the opening with cement. Another small thermometer was placed with its ball close to the case, and as near to that part to which the weight was approached as could be done with safety ; the ther- mometers being so placed, that when the weights were in the negative position, both could be seen through one of the telescopes, by means of light reflected from a concave mirror. Three other experiments were then made with this apparatus, viz. exper. 6 on Sept. 6, exper. 7 on Sept. 1 8, and exper 8 on Sept. 23 ; the results of which were as follow : viz. Sept. 6. Motion of arm on moving weights from midway to — = 3.03 — to + = 5.9 Sept. 18. Motion of arm on moving weights from midway to — =3.15 — to+ =6.1 Sept. 23. Motion of arm on moving weights from midway to — = 3.13 — to -f- = 5.72 In these 3 experiments, the effect of the weight appeared to increase from 2 to 5-10ths of a division, on standing an hour; and the thermometers showed, that the weights were 3 or 5-10ths of a degree warmer than the air close to the case. In the last 2 experiments, I put a lamp into the room, over night, in hopes of making the air warmer than the weights, but without effect, as the heat of the weights exceeded that of the air more in these 2 experiments than in the former. On the evening of October 17, the weights being placed in the midway position, lamps were put under them in order to warm them ; the door was then shut, and the lamps suffered to burn out. The next morning it was found, on moving the weights to the negative position, that they were 71° warmer than the air near the case. After they had continued an hour in that position, they were found to have cooled l-£°, so as to be only 6° warmer than the air. They were then moved to the positive position ; and in both positions the arm was drawn aside about 4 di- visions more, after the weights had remained an hour in that position, than it was at first. VOL. LXXXVIII.] PHILOSOPHICAL TRANSACTIONS. 397 May 22, 17Q8. The experiment was repeated in the same manner, except that the lamps were made so as to burn only a short time, and only 2 hours were suffered to elapse before the weights were moved. The weights were now found to be scarcely 2° warmer than the case ; and the arm was drawn aside about 2 divisions more, after the weights had remained an hour in the position they were moved to, than it was at first. On May 23, the experiment was tried in the same manner, except that the weights were cooled by laying ice on them ; the ice being confined in its place by tin plates, which, on moving the weights, fell to the ground, so as not to be in the way. On moving the weights to the negative position, they were found to be about 8° colder than the air, and their effect on the arm seemed now to diminish on standing, instead of increasing, as it did before ; as the arm was drawn aside about 2-^ divisions less, at the end of an hour after the motion of the weights, than it was at first. It seems sufficiently proved therefore, that the effect in question is produced, as above explained, by the difference of temperature between the weights and case ; for, in the 6th, 8th, and 9th experiments, in which the weights were not much warmer than the case, their effect increased but little on standing ; whereas it in- creased much when they were much warmer than the case, and decreased much when they were much cooler. It must be observed, that in this apparatus the box in which the balls hang must be near the bottom of it, which makes the effect of the current of air more sensible than it would otherwise be, and is a defect which I intend to rectify in some future experiments. v After this were made 3 other experiments, with the weights first in the positive and then moved to the negative position ; viz. exper. 9 on April 29, exper. 10 on May 5, and exper. 1 1 on May 6 ; the results of which were as follow : viz. April 29. Motion of arm = 6.32 Time of vibration = 6m 58s May 5. Motion of arm as 6.15 Time of vibration = 6m 59s May 6. Motion of arm = 6.07 Time of vibration = 7m Is In the foregoing 3 experiments, the index was purposely moved so that, before the beginning of the experiment, the balls rested as near the sides of the case as they could, without danger of touching it ; for it must be observed, that when the arm is at 35, they begin to touch. In the following 2 experiments, the index was in its usual position. Next follow 3 more such experiments, by varying the posi- tions from negative to positive, and the contrary; viz. exper. 12, 13, 14, on May 9, 25, 26 respectively ; the results of which are as follow . viz. Exper. 12. Motion of arm = 6.09 Time of vibration = 7m 3s &Q8 PHILOSOPHICAL TRANSACTIONS. [ANNO 1798. Exper. 13. Motion of the arm on moving weights from — to -f- = 6.12 + to - = 5.97 Time of vibration at , 4. = 7m g« - = 7 7 Exper. 14. Motion of arm by moving the weights from — to + = 6.27 -f- to — = 6.13 Time of vibration at -J- = 7m 69 - = 7 6 In the next experiment 15, on May 27, the balls, before the motion of the weights, were made to rest as near as possible to the sides of the case, but on the contrary side from what they did in the 9th, 10th, and 1 1 th experiments. The result as follows : Exper. 15. Motion of the arm from -f- 6.34 Time of vibration 7m 7s The following 2 experiments, 16, 17, on May 28 and 30, were made by Mr. Gilpin, who was so good as to assist me on the occasion. The results thus : Exper. 16. Motion of the arm =6.1 Time of vibration = 7m 16s Exper. 17. Motion of the arm on moving weights from — to -f- = 5.78 -f to — s= 5.64 Time of vibration at -\- = ym 29 - =7 3 On computing the density of the earth from these experiments. — I shall first compute this, on the supposition that the arm and copper rods have no weight, and that the weights exert no sensible attraction, except on the nearest ball ; and shall then examine what corrections are necessary, on account of the arm and rods, and some other small causes. The first thing is, to find the force required to draw the arm aside, which, as before said, is to be determined by the time of a vibration. The distance of the centres of the 2 balls from each other is 73.3 inches, and therefore the distance of each from the centre of motion is 36.65, and the length of a pendulum vibrating seconds, in this climate, is 39.14 ; therefore, if the stiff- ness of the wire by which the arm is suspended is such, that the force which must be applied to each ball, in order to draw the arm aside by the angle a, is to the weight of that ball, as the arch of a to the radius, the arm will vibrate in the same time as a pendulum whose length is 36.65 inches, that is, in \/%r-r. seconds; and therefore, if the stiffness of the wire is such as to make it vibrate in n seconds, the force which must be applied to each ball, in order to draw it aside by the angle A, is to the weight of the ball, as the arch of A X -, X %^n: to tne ra^ms* But the ivory scale at the end of the arm is 38.3 inches from the centre of motion, VOL. LXXXVII1.] PHILOSOPHICAL TRANSACTIONS. 3QQ and each division is T»T of an inch, and therefore subtends an angle at the centre, whose arch is -^^ ; therefore the force which must be applied to each ball, to draw the arm aside by 1 division, is to the weight of the ball, as gg ^^Tl to l> or as ah tol- The next thing is, to find the proportion which the attraction of the weight on the ball bears to that of the earth on it, supposing the ball to be placed in the middle of the case, that is, to be not nearer to one side than the other. When the weights are approached to the balls, their centres are 8.85 inches from the middle line of the case; but, through inadvertence, the distance, from each other, of the rods which support these weights, was made equal to the distance of the centres of the balls from each other, whereas it ought to have been somewhat greater. Tn consequence of this, the centres of the weights are not exactly oppo- site to those of the balls, when they are approached together; and the effect of the weights, in drawing the arm aside, is less than it would otherwise have been, in the triplicate ratio of rg-g? to the chord of the angle whose sine is ^~r, or in the triplicate ratio of the cosine of 4- this angle to the radius, or in the ratio of .9779 to 1. Each of the weights weighs 243()000 grains, and therefore is equal in weight to 30.64 spherical feet of water; therefore its attraction on a particle placed at the centre of the ball, is to the attraction of a spherical foot of water on an equal par- ticle placed on its surface, as 10.64 X .9779 X (^~f5Y to 1. The mean diameter of the earth is 41800000 feet*; and therefore, if the mean density of the earth be to that of water as d to 1, the attraction of the leaden weight on the ball will be to that of the earth on it, as 10.64 X -9779 X (g^)2 to 41800000D :: l to 8739000D. It is shown therefore, that the force which must be applied to each ball, in order to draw the arm 1 division out of its natural position, is ■ ; of the weight of the ball ; and if the mean density of the earth be to that of water as d to 1 , the attraction of the weight on the ball is rr^-r^-r^- of the weight of that ball ; therefore the at- 0 8/oyOOOD ° 010 -|u2 traction will be able to draw the arm out of its natural position by -jf^^r- or divisions; and therefore, if on moving the weights from the midway to a 10683d near position the arm is found to move b divisions, or if it moves 2b divisions on moving the weights from one near position to the other, it follows that the density of the earth, or d, is jog^- * In strictness, we ought, instead of the mean diameter of the earth, to take the diameter of that Bphere whose attraction is equal to the force of gravity in this climate j but the difference is not worth regarding.— Orig. 400 PHILOSOPHICAL TRANSACTIONS. [ANNO 1798. We must now consider the corrections which must be applied to this result; first, for the effect which the resistance of the arm to motion has on the time of the vibration : 2d, for the attraction of the weights on the arm : 3d, for their attraction on the farther ball: 4th, for the attraction of the copper rods on the balls and arm: 5th, for the attraction of the case on the balls and arm: and 6th, for the alteration of the attraction of the weights on the balls, according to the position of the acm, and the effect which that has on the time of vibration. None of these corrections indeed, except the last, are of much signification, but they ought not entirely to be neglected. As to the first, it must be considered, that during the vibrations of the arm and balls, part of the force is spent in accelerating the arm; and there- fore, in order to find the force required to draw them out of their natural position, we must find the proportion which the forces spent in accelerating the arm and balls bear to each other. Let EDCec/c, fig. 4, be the arm; b and b the balls; cs the suspending wire. The arm consists of 4 parts: first, a deal rod vcd, 73.3 inches long; 2d, the silver wire Dcd, weighing 170 grains; 3d, the end pieces de and ed, to which the ivory vernier is fastened, each of which weighs 45 grains; and 4th, some brass work cc, at the centre. The deal rod, when dry, weighs 2320 grains, but when very damp, as it commonly was during the experiments, weighs 2400; the transverse section is of the shape represented in fig. 5 ; the thickness ba, and the dimensions of the part DEed, being the same in all parts ; but the breadth b& diminishes gradually, from the middle to the ends. The area of this section is .33 of a square inch at the middle, and .146 at the end; therefore, if any points (fig. 4) be taken in cd, and 4 be called x, this rod weighs -— — '-—1 per inch at the middle; ' cd ° 73.3 X .'238 r 2400 x .14-6 ., , , 2400 w .33 - .184 x 3320 — 1848 * , , . 73.3 x .238 at the end' and TO X .238 ' = 73~3 at *'> and therefore, as the weight of the wire is — - per inch, the deal rod and wire together may be considered as a rod whose weight at x = rrr per inch. But the force required to accelerate any quantity of matter placed at x, is pro- portional to a:2; that is, it is to the force required to accelerate the same quantity of matter placed at d, as a?2 to 1 ; and therefore, if cd be called /, and x be sup- posed to flow, the fluxion of the force required to accelerate the deal rod and wire is proportional to ~ x ^^f 1848x), the fluent of which, generated while x flows from c to d, is = — — X'-J ; • — -r- == 350; so tnat tne f°rce required to 73.3 3 4 accelerate each half of the deal rod and wire, is the same as is required to acce- lerate 350 grains placed at d. The resistance to motion of each of the pieces de, is equal to that of 48 grains placed at d\ as the distance of their centres of gravity from c is 38 inches. The resistance of the brass work at the centre may be disregarded; and therefore the VOL. LXXXVIII.] PHILOSOPHICAL TRANSACTIONS. 401 whole force required to accelerate the arm, is the same as that required to accelerate 398 grains placed at each of the points d and d. Each of the balls weighs 11 262 grains, and they are placed at the same distance from the centre as d and d; therefore the force required to accelerate the balls and arm together, is the same as if each ball weighed ll66o, and the arm had no weight; and therefore, supposing the time of a vibration to be given, the force required to draw the arm aside, is greater than if the arm had no weight, in the proportion of 11660 to 11262, or of 1.0353 to 1. To find the attraction of the weights on the arm, through ddraw the vertical plane dwb perpendicular to vd, and let w be the centre of the weight, which, though not accurately in this plane, may without sensible error be considered as placed in it, and let b be the centre of the ball; then wb is horizontal and = 8.85, and db is vertical and =5.5; let wd = a, wb = b} and let ^, or 1 — x = z; then the attraction of the weight on a particle of matter at x, in the direction duo, is to its attraction on the same particle placed at b :: b3 : (a2 + *2^2)*> or 1S proportional to rrra, and the force of that attraction to move the arm, is proportional to (a1 + zHz)^ r r AX^T,Z?3 ; but the weight of the deal rod and wire at the point x, was before said (a* + z2l1)^ ° r 3 to be ?!f ■ ~A. , = - — r~ per inch ; therefore, if dx flows, the fluxion of the .. 7- w 1642 + 1848z . 6sx(l-z) ,n v power to move the arm is = Iz X ^ h ,a> + ^a = z X (821 + g24z) 924a1 b*z x (821 + 103z + ) b* x(l-z) _ Vk X (821 + 103z - 924zg) __ ' lj_ X (a* + /V)£ ~~ (a* + /V)f. (a* + /V)f a1 9246?z x ( — + z1) ■ g which as -— OS is — b* * (895 + I032) 9246>* The fluent of this is 8956'z 10365 . 1036' 924/>3 . h + J (a* + fV) JtI_ - = av(a + /V) " M«h¥) + 7* - -~ loS- ~a — ; and the force with which the attraction of the weight, on the nearest half of the deal rod and wire, tends to move the arm, is proportional to this fluent generated while z flows from 0 to I , that is, to ] 28 grains. The force with which the attraction of the weight on the end-piece de tends to move the arm, is proportional to A^ X -, or 29 grains; and therefore the whole power of the weight to move the arm, by means of its attraction on the nearest part of it, is equal to its attraction on 157 grains placed at b} which is —3-, or .0139 of its attraction on the ball. It must be observed, that the effect of the attraction of the weight on the whole arm is rather less than this, as its attraction on the farther half draws it the contrary way; but as the attraction on this is small, in comparison of its attraction on the nearer half, it may be disregarded. vol. xviii. 3 F 402 PHILOSOPHICAL TRANSACTIONS. [ANNO 17Q8. The attraction of the weight on the farther ball, in the direction bw, is to its at- traction on the nearer ball :: ud3 : wd3 :: .0017 : 1; and therefore the effect of the attraction of the weight on both balls, is to that of its attraction on the nearer ball :: .9983 : 1 . To find the attraction of the copper rod on the nearer ball, let b and w, fig. 6, be the centres of the ball and weight, and ea the perpendicular part of the copper rod, which consists of 2 parts, ad and de: ad weighs 22000 grains, and is 16 inches long, and is nearly bisected by w\ de weighs 41000, and is 46 inches lone-; wb is 8.85 inches, and is perpendicular to ew. Now the attraction of a line ew, of uniform thickness, on b, in the direction bw9 is to that of the same quantity of matter placed at w :: bw : eb\ therefore the attraction of the part da equals that of ~~°~L* — • or 1^300j placed at w; and the attraction of de equals that of 41000 X ^ x T "" 41000 x Td X M» °r 2500> Placed at the same point; so that the attraction of the perpendicular part of the copper rod on b, is to that of the weight on it, as 18800 : 2439000, or as .00771 to 1. As for the attraction of the in- clined part of the rod and wooden bar, marked vr and rr in fig. 1, it may safely be neglected, and so may the attraction of the whole rod on the arm and farthest ball; therefore the attraction of the weight and copper rod, on the arm and both balls together, exceeds the attraction of the weight on the nearest ball, in the pro- portion of .9983 -f- .0139 -f- .0077 to 1, or of I.OI99 to ]. The next thing to be considered, is the attraction of the mahogany case. Now it is evident, that when the arm stands at the middle division, the attractions of the opposite sides of the case balance each other, and have no power to draw the arm either way. When the arm is removed from this division, it is attracted a little towards the nearest side, so that the force required to draw the arm aside is rather less than it would otherwise be ; but yet, if this force is proportional to the distance of the arm from the middle division, it makes no error in the result; for though the attraction will draw the arm aside more than it would otherwise do, yet, as the accelerating force by which the arm is made to vibrate is diminished in the same proportion, the square of the time of a vibration will be increased in the same proportion as the space by which the arm is drawn aside, and therefore the result will be the same as if the case exerted no attraction; but if the attraction of the case is not proportional to the distance of the arm from the middle point, the ratio in which the accelerating force is diminished is different in different parts of the vibration, and the square of the time of a vibration will not be increased in the same proportion as the quantity by which the arm is drawn aside, and therefore the result will be altered by it. On computation, I find that the force by which the attraction draws the arm from the centre is far from being proportional to the distance, but the whole force is so small as not to be worth regarding; for, in no position of the arm does the VOL. LXXXVIII.] PHILOSOPHICAL TRANSACTIONS. 403 attraction of the case on the balls exceed that of -fth of a spheric inch of water, placed at the distance of 1 inch from the centre of the balls; and the attraction of the leaden weight equals that of 10.6 spheric feet of water placed at 8.85 inches, or of 234 spheric inches placed at 1 inch distance; so that the attraction of the case on the balls can in no position of the arm exceed , /7 , of that of the weight. The compuration is given in the Appendix. It has been shown therefore, that the force required to draw the arm aside 1 division, is greater than it would be if the arm had no weight, in the ratio of 1.0353 to 1, and therefore is = j^r of the weight of the ball; also, the at- traction of the weight and copper rod on the arm and both balls together, exceeds the attraction of the weight on the nearest ball, in the ratio of I.OI99 to 1, and therefore is = 873q000d °f tne weight of the ball ; consequently d is really equal 818N* l.OlQQ Na . , r N* i ,i /• toT5553 x m§556i> or1wiir> msteadof T5683T' as by the former <=°mputa- tion. It remains to be considered how much this is affected by the position of the arm. Suppose the weights to be approached to the balls ; let w, fig. 7, be the centre of one of the weights ; it the centre of the nearest ball at its mean position, as when the arm is at 20 divisions ; let b be the point which it actually rests at ; and A the point which it would rest at, if the weight was removed ; consequently ab is the space by which it is drawn aside by means of the attraction ; and let m(3 be the space by which it would be drawn aside, if the attraction on it was the same as when it is at m. But the attraction at b is greater than at m, in the proportion of wm2 : wb2; and therefore ab = m(3 x — r = m(3 X (1 H — — ) very nearly. Let now the weights be moved to the contrary near position, and let w be now the centre of the nearest weight, and b the point of rest of the centre of the ball ; then Ai = m(3 X 1 + M, andBi = m(3 X 1 + ^- + ~ = ^Hx (l+£), so that the whole motion b6 is greater than it would be if the attraction on the ball was the same in all places as it is at m, in the ratio of 1 4 to 1 ; and there- fore does not depend sensibly on the place of the arm, in either position of the weights, but only on the quantity of its motion, by moving them. This variation in the attraction of the weight affects also the time of vibration ; for suppose the weights to be approached to the balls, let w be the centre of the nearest weight ; let b and a represent the same things as before ; and let x be the centre of the ball, at any point of its vibration ; let ab represent the force with which the ball, when placed at b, is drawn towards a by the stiffness of the wire ; then, as b is the point of rest, the attraction of the weight on it will also equal ab ; and when the ball is at x9 the force with which it is drawn towards a, by the stiff- ness of the wire, is as ax, and that with which it is drawn in the contrary direction, 3 F2 404 PHILOSOPHICAL TKANSACTIONS. [ANNO 1798. BW by the attraction, =ab X — « ? so that the actual force by which it is drawn to- wards A is = AX — 5 = AB + B07 — AB X (H — ) 3± BX— 2BX X AB wr v ' wb ' WB ? very nearly. So that the actual force with which the ball is drawn towards the mid- dle point of the vibration, is less than it would be if the weights were removed, in the ratio of J to 1, and the square of the time of a vibration is increased in the ratio of J to 1 — — — ; which differs very little from that of 1 4- b6 to 1 which is the ratio in which the motion of the arm, by moving the weights from one near position to the other, is increased. The motion of the ball answering; to 1 division of the arm, is = '■ ; and b ' 20x38.3 ' if wb be the motion of the ball answering to d divisions on the arm, l£r = 20 x f*Tx 8.85 P W5 ; therefore the time of vibration, and motion of the arm, must be corrected as follows : If the time of vibration is determined by an ex- periment in which the weights are in the near position, and the motion of the arm, by moving the weights from the near to the midway position, is d divisions, the ob- served time must be diminished in the subduplicate ratio of 1 to 1, that is, 185 in the ratio of 1 — to 1 ; but when it is determined by an experiment in which the weights are in the midway position, no correction must be applied. To correct the motion of the arm caused by moving the weights from a near to the midway position, or the reverse, observe how much the position of the arm diners from 20 divisions, when the weights are in the near position : let this be n divisions, then if the arm at that time be on the same side of the division of 20 as the weight, the observed motion must be diminished by the — — part of the whole; but otherwise it must be as much increased. If the weights are moved from one near position to the other, and the motion of the arm be 2d -divisions, the observed motion must be diminished by the — — - part of the whole. If the weights are moved from one near position to the other, and the time of vibration be determined while the weights are in one of those positions, there is no need of correcting either the mo- tion of the arm, or the time of vibration. Y0L. LXXXVIII.] PHILOSOPHICAL TRANSACTIONS, 405- CONCLUSION. The following Table contains the Result of the Experiments. 1 { m. to + + to m. 2 { m. to + -f- to m. 3 { -f to m. m. to + f m. to -f 4 { + to - - to + 5 { + to — — to + 6 { m. to — - to + 7 { m. to — - to + 8 { m. to — - to + 9 + to - 10 + to - 11 + to - 12 — to + 13 { — to -j- -f to — 14 { - to + + to - 15 - to + 16 17 { — to + — to + + to - Mot. arm Do. corr. Time vib. Do . corr. Density. 14.32 13.42 m. s. 5.50 14.1 13.17 14.55 5.61 15.87 14.69 . 4.88 15.45 14.14 14.42 5.07 15.22 13.56 14.39 5.26 14.5 13-28 14.54 5.55 3.1 295 6 .54 5.36 6.18 . 7.1 5.29 5.92 • . 7-3 5.58 5.9 . 7.5 5.65 5.98 . 7.5 5.57 3.03 2.9 1 • 5.53 5.9 5.71 7.4 5.62 3.15 6.1 3.03 5.9 6 57 5.29 5.44 3.13 3.00 mean. 5.34 5J2 5.54 „ • 5.79 6.32 # 6.58 5.10 6.15 , 6.59 5.27 6.07 ( . 71 5.39 6.09 . 7.3 5.42 6.12 , 7.6 5-47 5.97 . 7.7 5.63 6.27 # 7.6 5.34 6.13 # 7.6 5.46 6.34 # 7.7 5.30 6.1 . 7.16 5.75 5.78 - . 7.2 5.68 5.64 . 7.3 5.85 From this table it appears, that though the experiments agree pretty well to- gether, yet the difference between them, both in the quantity of motion of the arm and in the time of vibration, is greater than can proceed merely from the error of observation. As to the difference in the motion of the arm, it may very well be accounted for, from the current of air produced by the difference of temperature ; but whether this can account for the difference in the time, of vibration, is doubtful. If the current of air was regular, and of the same swiftness in all parts of the vibra- tion of the ball, I think it could not ; but as there will most likely be much irregu- larity in the current, it may very likely be sufficient to account for the difference. By a mean of the experiments made with the wire first used, the density of the earth comes out 5.48 times greater than that of water ; and by a mean of those made with the latter wire, it comes out the same ; and the extreme difference of the results of the 23 observations made with this wire, is only .75 ; so that the extreme results do not differ from the mean by more than .38, or -V of the whole, and therefore the density should seem thus to be determined, to great exactness. It may indeed be objected, that as the result appears to be influenced by the current of air, or some other cause, the laws of which we are not well acquainted with, this 406 PHILOSOPHICAL TRANSACTIONS. [ANNO 1798. cause may perhaps act always, or commonly, in the same direction, and so make a considerable error in the result. But yet, as the experiments were tried in various weathers, and with considerable variety in the difference of temperature of the weights and air, and with the arm resting at different distances from the sides of the case, it seems very unlikely that this cause should act so uniformly in the same way, as to make the error of the mean result nearly equal to the difference between this and the extreme ; and therefore it seems very unlikely that the density of the earth should differ from 5.48 by so much as T'T of the whole. Another objection perhaps may be made to these experiments, namely, that it is uncertain whether, in these small distances, the force of gravity follows exactly the same law as in greater distances. There is no reason however to think that any irregularity of this kind takes place, until the bodies come within the action of what is called the attraction of cohesion, and which seems to extend only to very minute distances. With a view to see whether the result could be affected by this attrac- tion, I made the 9th, 10th, 11th, and 15th experiments, in which the balls were made to rest as close to the sides of the case as they could ; but there is no differ- ence to be depended on, between the results under that circumstance, and when the balls are placed in any other part of the case. According to the experiments made by Dr. Maskelyne, on the attraction of the hill Schehallien, the density of the earth is 44.* times that of water ; which differs rather more from the preceding determination than I should have expected. But I forbear entering into any consideration of which determination is most to be de- pended on, till I have examined more carefully how much the preceding determina- tion is affected by irregularities whose quantity I cannot measure. Appendix. — On the Attraction of the Mahogany Case on the Balls. The first thing is, to find the attraction of the rectangular plane ckfib (fig. 8,) on the point a, placed in the line ac perpendicular to this plane. a* bz Let ac = a, ck = b, cb = x, and let 5 = w1, and , = = i/2, then the attraction of the line bQ on a. in the direction ab, is = -v- — - ; and therefore, if ao -f- ap * cb flows, the fluxion of the attraction of the plane on the point a, in the direction cb, bx X — bw —bw — v "~ vV + x* x Vaz + b1-rxi ^a7 + x1 " /Z~.~t ~~" ^b*wz + ax ~~ ^\ + vq ' ■V ° + a the variable part of the fluent of which is = — log. v + ^ 1 + t/2, and therefore the whole attraction is == log. (c + a x ,a °, a) so that the attraction of the plane, 0 v ac p/3 + a/3 ' in the direction cb, is found readily by logarithms, but I know no way of finding * The mean density of the earth by that experiment, has since been found to be nearly 5, or 5 times that of water, by taking the real density of the hill, instead of one that was assumed below the truth. See p. 420, vol. 14, of these abridgments. PHILOSOPHICAL TRANSACTIONS. 407 TOL. LXXXVIII.] its attraction in the direction ac, except by an infinite series. The two most con- venient series I know, are the following : First series. Let - = tt, and let a = arc whose tang, is tt, b = a — tt, it* c== B _|. — p = c — y, &c. then the attraction in the direction ac = V 1 _ X (a + 3 IV . 3cw4 ,3.5a;6 0 x For the second series, let a = arc whose tang. = -, b = a , c = b -f- I (A- D == C — 3ciH BV1 + 5sr* ' 3 . 5dv6 &c. then the attraction = arc 90° — ^ [(1 -4- ^2) x , &c.)] 2 " 2.4 2.4.6: It must be observed, that the first series fails when ?r is greater than unity, and the 2d, when it is less ; but if h is taken equal to the least of the 2 lines ck and cb, there is no case in which one or the other of them may not be used conveniently. By the help of these series, I computed the following table. .1962 .3714 .1962 .00001 .3714 .00039 00148 .5145 .00074 00277 .6248 00110 00406 .7071 00140 00522 .7808 00171 00637 .8575 00207 00772 .9285 00244 009»0 .9815 00271 01019 1- 00284 01054 .5145 .6248 .7071 .7808 .8575 .9285 •9815 1. 00521 00778 01183 01008 01525 02002 01245 01 896 02405 03247 01522 02339 03116 03964 05057 01810 02807 03778 04867 06319 08119 02084 03193 04368 05639 07478 09931 12849 02135 03347 04560 05975 07978 10789 14632 19612 Find in this table, with the argument -r at top, and the argument -?■ in the left QfC (lb hand column, the corresponding logarithm ; then add together this logarithm, the logarithm of —t and the logarithm of -7- ; the sum is logarithm of the at- traction. To compute from hence the attraction of the case on the ball, let the box dcba, fig. 1, in which the ball plays, be divided into 2 parts, by a vertical section, per- pendicular to the length of the case, and passing through the centre of the ball ; and, in fig. 9, let the parallelopiped ABVEabde be one of these parts, abde being the above-mentioned vertical section ; let x be the centre of the ball, and draw the parallelogram finpmSx parallel to -&bdj), and xgrp parallel to j3b^w, and bisect $$ in c. Now the dimensions of the box, on the inside, are b£ = 1.75; bd = 3.6; B0 = 1.75 ; and (3a = 5 ; whence I find, that if xc and jar be taken as in the 2 upper lines of the following table, the attractions of the different parts are as follows. 408 PHILOSOPHICAL TRANSACTIONS. [ANNO 17 QS. xc , 75 .5 .25 (3j? 1.05 1.3 1.55 Excess of attraction of ndrg above Bbrg 23/4 .1614 .0813 mdrp above nbrp 2374 .l6l4 .08 13 — mesp above nasp 3705 .25 16 .1271 Sum of these 8453 .5744 .2897 Excess of attraction of Bbnfi above vdmS 5007 .3271 .1606 Aanj3 above Eem$ 4677 -3079 -1525 Whole attraction of the inside surface of the half box . . .1231 .0606 .0234 It appears therefore, that the attraction of the box on x increases faster than in proportion to the distance occ. The specific gravity of the wood used in this case is .6l, and its thickness is £ of an inch ; therefore, if the attraction of the outside surface of the box was the same as that of the inside, the whole attraction of the box on the ball, when ex = .75, would be equal to 2 X .1231 X .61 X 4- cubic inches, or, .201 spheric inches of water, placed at the distance of 1 inch from the centre of the ball. In reality, it can never be so great as this, as the attraction of the outside surface is rather less than that of the inside ; and besides, the distance of x from c can never be quite so great as .75 of an inch, as the greatest motion of the arm is only 14- inch. XXII. An Improved Solution of a Problem in Physical Astronomy ; by which, swiftly converging Series are obtained, which are useful in computing the Pertur- bations of the Motions of the Earth, Mars, and Venus, by their mutual At- traction. To which is added an Appendix, containing an easy Method of obtaining the Sums of many slowly converging Series which arise in taking the Fluents of binomial Surds, &c. By the Rev. John Hellins, F. R. S. p. 527. It was with much diffidence that I entered on a speculation which had engaged the attention of such learned men as Simpson, Euler, and La Grange. Consider- ing the great abilities of these men, and the length of time which Euler, in par- ticular, appears to have employed on the subject, all that I at first expected to effect was, to facilitate the summation of the slowly converging series by means of which they had computed the perturbations of the motions of the planets in their orbits, which arise from their actions on one another, by the force of gravity; and that this might be done by a method which I had some time before discovered, was evident, on inspecting their series. Here probably I should have stopped, had not Dr. Maskelyne put into my hands a sheet of paper, written by the late Mr. Simpson, which, though very ingenious, was by mistakes, which seem to have entered in transcribing it, rendered unintelligible to some eminent mathema- VOL. LXXXVIII.] PHILOSOPHICAL TRANSACTIONS. 40Q ticians who had perused it; in which state it had remained 36 years. On perusing this paper, the first thing that occurred to me was, a different method of finding the fluent, from that which had been used by Mr. Simpson ; by which means, series converging by the powers of £ were obtained, while the series brought out the common way lost all convergency by a geometrical progression, and a compu- tation by it was more difficult than the computation of the length of a quadrantal 1 3 3 5 arch of the circle by the series 1 + — - -f- ■ + 4" g , &c. I afterwards discovered the method of transforming that series which had lost all convergency by a geometrical progression, into another in which the literal powers decrease very swiftly; which is the improvement now offered. In comparing the series here produced, for computing the values of a and b in the equation (a — b X cos. z) -" = a -j- B • cos. z + c . cos. 2z + d . cos. 3z + &c. with those which have been published for that purpose, by Messrs. Euler and la Grange, it will appear, that those cases which were the most difficult to be computed by their methods, are the most easy by mine. For instance, if Venus's perturbation of the motion of the earth were to be computed, and vice versa1, the literal powers which have place in Euler's series, would be very nearly equal to the powers of -^-; the literal powers which have place in la Grange's series, would be nearly equal to the powers of $; and in the series now produced the literal powers would decrease somewhat swifter than the powers of -g^-* M. la Grange has indeed, by a very ingenious device, obtained a convergency in the numeral co-efficients of the series that he uses, which, for the first 5 terms of it, is nearly equal to the powers of -^; but this convergency becomes less and less in every succeeding term, and the co-efficients approach pretty fast to a ratio of equality; so that, to obtain the sum of the series to 6 places of decimals, he pro- poses to compute the first 10 terms of it. The case in which those co-efficients have that convergency, is when n (which answers to his sy) is = — ->., a case which does not often happen; however, from the values of a and b, when n = — 4-, he derives their values when n = 4-, -§-, &c. by another very ingenious device, worthy of that skill for which he is justly celebrated. But by the method now proposed the chief part of the convergency is in the literal powers; and such a difference in the numeral co-efficients, for a different value of n, does not take place. For Mars's perturbation of the earth's motion, the literal powers by which the 3 different series converge, are nearly as follows: M. Euler's, S f -f; M. la Grange's, \ by the powers of ) 4-§-; The series now proposed, ) t~rs- * * For obtaining nearly the different rates of convergency of the literal powers in the 3 series, it will be sufficient to consider the distance of the 2 planets of which the perturbations are to be computed, as = V"(RR + rr — 2ftr x c, z,) where r and r denote their mean distances from the sun, of which r VOL. xviii. 3 G 410 PHILOSOPHICAL TRANSACTIONS. [ANNO 1798. If indeed the perturbation which arises from the action of Jupiter on the earth was to be computed, la Grange's series would be the best that has hitherto been published for the purpose, as the literal powers of it would, in that case, be nearly equal to the powers of -,V, while the literal powers in the new series would differ but little from those of 44. So that, for computing the perturbation of each of these 3 planets, we now have series converging so very swiftly, that the first 4 terms are sufficient for the purpose. These indeed are the perturbations of motion, arising from the actions of the planets, which the inhabitants of this globe have most frequent occasion to compute. And since 2 of the 3 are most easily cal- culated by the method explained in the following pages, I am not without hopes that I have rendered an acceptable piece of service to astronomers in general, and more especially to those who are most intent on improving astronomi- cal tables. But it may be proper to remark, that the use of the new series is not confined to the computations just mentioned, but may successfully be used in computing the perturbations of the motions of other planets. For instance, in the computation of the perturbation of Saturn's motion by Jupiter, and vice versa, the convergency of this series will be nearly by the powers of -j^, which is a swift rate of conver- gency. And, for the perturbation of the Georgium sidus by Saturn, and vice versa, the series will converge nearly by the powers of -f, which is also swiftly. And it is further to be remarked, that in the last instance, and indeed whenever the radii of the orbits of the 2 planets differ from each other in the ratio of 2 to 1, M. la Grange's series may be used with advantage, since the convergency of the first 5 terms of it will then be nearly by the powers of -^\ the numeral co-efficients of those terms converging as swiftly as the literal powers do in that case. And when the ratio of the 2 radii is greater than that of 2 to 1, his series will converge more swiftly. An improved Solution of a Problem in Physical Astronomy, 6?c. 1. The perturbation of the motions of the planets in their orbits, by their actions on each other, is a curious phenomenon, which, while it affords to the philosopher a clear proof of the general attraction of matter, produces a problem of no small difficulty to the astronomer; viz. to compute the quantity by which a planet, so acted on, deviates from an ellipsis in its course round the sun : a pro- is the greater, and c, z the cosine of the angle of commutation. Then will M. la Grange's series con- TT verge by the powers of the quantity — j and, since rr + rr = a, and 2Rr = b, in our notation, and R R bb 4rV* the converging quantity in M. Euler's series is (nn) = — , it will be se r : and cc, by the ° ° n ' aa (rr -f rr)1 CL "™~ h R.R — — 2R7* -4" TT ( R ~" t*f powers of which the new series converges, is = , = = - r-.. See the ^ * a + b rr + 2Rr + rr (r + r)1 Memoirs of the Royal Academy of Sciences and Belles-Lettres at Berlin, for 1781, p. 257 5 M. Euler'« Institutiones Calculi Integralis, vol. 1, p. 186} and art. 4, in what follows. — Orig. 9 *tOL. LXXXVIII.] PHILOSOPHICAL TRANSACTIONS. 411 blem which has called forth the skill of several of the most learned philosophers and astronomers of the last and present age. A preparatory step to the solution of this problem is, to find a convenient ex- pression for the reciprocal of the cube, or rather of the nth power, of the distance of any 2 planets. Such an expression was first given by Euler, in series proceeding by the cosines of the multiples, in arithmetic progression, of the angle of commu- tation ; but the calculations of the first 2 co-efficients in it were very laborious, re- quiring the summation of series of the common form, which converged very slowly. Afterwards, other series were discovered by other authors, by which the same co-efficients might be computed with less labour; the best of which, that I have seen, appear to be those that were pointed out to me by Dr. Maskelyne, invented by la Grange, and published in the memoirs of the Royal Academy of Sciences at Berlin, for the year 1781 . Yet the calculation of the first 2 co-efficients, a and b, for the perturbations of Mars, Venus, and the earth, by his method, is not shorter, if it be so short as by my method, to the investigation of which I now proceed. Prob. — 2. To determine the values of a, b, c, d, &c. in the equation -^ - = z (a + b . cos. z 4- c . cos. 2z + d. cos. 3z, &c.) z being the (c — b . cos. z)" v ' ■ ' * ' ° arch of a circle of which the radius is 1, and b less than a. First, to find the co-efficient a. — 3. The fluent of the right-hand side of this equation is az + b . sin. z + 4c . sin. 2z -f 4d . sin. 3z -f ^e . sin. 4z*, &c. which evidently vanishes when z = O; and when z = 3*14159, &c« tne arcn of 180°, it becomes barely = az, the sines of z, 2z, 3z, &c. being then each = 0. There- fore if the fluent of the first side of the equation be taken, the increase of it, while z increases from O to 3*14159 &c. = w9 will be = tta; and consequently a will be determined. 4. Now, to find the fluent of ~ - = — - — =^— — , x being put (a— o.cos. z) //(l — xx) (a — bx)n ° r = the cosine of z ; in which expressions, while % increases from O to 3*14159, x will decrease from 1 to — 1 . Therefore, to obtain a more convenient expression, put vv = — T7T"J then, while x decreases from 1 to — 1, vv will increase from a-^—h to —r-i = 1 J ana< we shall have the following equation : -7 A 7-r. = (a + b)~n X //t , „ : ; the fluent of which may y(l — xx) (a — bx)n v ' V(l - vv) V(vv — cc) f be found when the value of n is given. 5. Now, the values of n with which astronomers are most concerned, are 4 and 4. Let therefore 4 be written for n, and the radical quantity ^(1 — vv) be converted into series, then the last expression will be 2i» — % vv . 3d4 , 3 . 5v* . 3.5. 7v * * See Euler' s Institutiones Calculi Integrals, vol. 1, p. 150 — Orig. 3 G2 412 PHILOSOPHICAL TRANSACTIONS. [ANNO 1798. f. 2'vV — 2 "% x ] V(vv-cc) — V°-rf7 V i 3w , 3.5e< , 3.5.7v6 - . (. "*" V(^ - cc) ^ "+" *T "T" 476 "•" TT6TS ' &c*' And the fluents of these several terms being taken, and collected together, then the whole multiplied by the common factor (a + b) * the fluent sought will be '2 j^(vv — cc) (a + b) T X < + * + i* + 5Av + i4*',te. 4 ' 4.6 ' ^4.6.8 6. We must now inquire what value this series has when z = O ; in which case, X being = 1, vv is = — — ft = cc. And it will appear that, with this value of vv, every term of the series vanishes, so that the fluent needs no correction. If, there- fore, we compute the value of this series when z = tt, i. e. when x = — J , and w = ~^-b = 1* we snaN have the value of A?r, and consequently, a will be deter- mined. But, with this value of v> the terms C, y} $t &c. lose all convergency by the geometrical progression, vf v3, t>5, &c. and the computation of the value of the series, by the common method, would be more laborious than the computation of the quadrantal arch of the circle, by the series 1 -J '-I 1 '— — , &c. n J ' 2.3 T2. 4.5 ^2. 4. 6. 7' Here then we are stopped. But, by contemplating this series, expressed in terms of a and c, and by making various ingenious transformations, in this and the 7th, 8th, and 9th articles, Mr. H. at length obtains 8 - 2cc * (a + 6)t 8 — 5cc [+•(!_ CC) . g + X + y.CC + VC*) 10. The value of a when n = 4 being now found, let us next investigate the value of it when n = -f- ; which, for the sake of distinction, in a use to be made of it in a subsequent article, Mr. H. denotes by a'. Here, by proceeding in a way similar to the foregoing, in this article, and the 11th, 12th, 13th, the au- thor at length obtains for the value of the arc in this case, the following form, viz. 96 — 23cc 128 — 84cc ,+ V(l - cc) . (i±^-C + / + /cc + „V). 2dly, tojind the Coefficient B. 14. Multiply the equation in art. 2. by 2 cos. z = 1x, and it gives _ = z (a X 2 cos. z -f b X 2 cos. z X cos. z -|- c X 2 cos. z X cos. 2z -f- d X 2 cos. z X cos. 3z, &c.) ; which, because 2 cos. z X cos. mz is = cos. {m — l) z -f- cos. (m-f l) z, will be = z (2a . cos. % -\- b (1 + cos. 2z) + c (cos. z -f cos- 3z) -f D (cos. 2z + cos. 4z), &c.).* And, by taking the fluents, we have / J* ss 2a . * See Simpson'a Miscellaneous Tracts, lemma i, p. 76. VOL. LXXXVIIl/J PHILOSOPHICAL TRANSACTIONS. 413 sin. z -f- bz + 4- b . sin. 2z + c (sin. z -f- -J- sin. 3z) + d (i sin. 2z -f- ^ sin. 4z), &c. ; which equation, when z = 3-J415Q, &c. = tt, becomes/—— ,^- = barely bz = Btt, the sines of z, 2z, 3z, &c. being then = O. 15. Now it appears, by the notation in art. 4, that _ = (a + b)~n X ^r — ; \, and that x = ^ ± — — ; we therefore have, by proper substitution, 2xz — 2xx ■ 2a 2-lv1 X (a — bx)n •" V(l - ») (« — **)" *"(« + *)" V(l - w) ( V(w — cc) - 2 2^3-3" 6 (a + 6)*'-1 X V(l — vv) */(yv~— *) of which 2 fluxions the fluents may be found, when n has any particular value. 16. First, let nbe|; then the last expression in the preceding article becomes X ... ffl. _, - r-^rr X „,_ " _,v Now, the fluent b(a + 6)| V(l — ct) V(w — cc) b(a + *)I -/(l — w) Vw — «w)' 2o of the affirmative part of this expression is evidently = — X the fluent of the fluxion in art. 5, that is, = — A?r , and the negative part, by converting -/ (l — vv) — — 2 2*w VV Sv^ 3 *>i?^ into series, will become ^-+-^ X £„_«) 0 + T + 2 . 4 + ifi^ *c.) ; the fluent of which appears, by art. 5, to be f^—rj)! (a 4" £ + ~r + rV + I*. u' *3 &c), which will vanish when v = c, and therefore needs no correction ; 4.0.8 and after further transformations and reductions, for the value of the co-efficient b, the ingenious author obtains the following expression : r 32 - lOcc B = ^A £__x)l6-9cc " 6 «H« + *U ^ + ^(x _ cc) (p _|_ ^ _f_ TC4)? which is its yalue when n = ■§-. 17. We are next to find the value of this co-efficient, when n = -§-; which, for the sake of distinction, he denotes by b'. With this value of n, the fluxionary ex- pression in art. 15, becomes 2a_ 2-:t>~4 2_. 2w~' ... , . 6(0 + 6)« X -v/(l - to) -/(to - cc) 6(0 +~6)f X -v/(l - vv) */{vv - cc) 5 WniC" DemS compared with the fluxions in art. 5 and 10, it will appear that the fluent of the former part, when v = 1, is = — aV, and that the fluent of the latter part is ==' T~ A?r ; which fluents, taken together, are, by art. 14, = bV. Therefore we have b = -r a — j- a = - (a a — - a). 3dly, to find the Values of c, d, e, &c. 18. The values of the co-efficients a and b being n6w found, corresponding to the values of n, -§- and 4, we might proceed in the same manner to find the value of c. For, if the equation in art. 2, be multiplied by 2 cos. 2z, and cos. (m — 2) z +• cos. (m + 2) z be written for 2 cos. 2« X cos. ws, it will become 414 PHILOSOPHICAL TRANSACTIONS. [ANNO 1798. (^TxTos^r = * (2A X COS* 2Z + B (COS* * + COS> 3^ + C 0 + C0S- 4«) + » (cos. z + cos. 52), &c.) And the sum of the fluents on the right-hand side, when z = «•, will become barely cz = ctt. Therefore, the fluent of the left-hand side of the equation, when z = ?r, will be = c?r. The fluent of this fluxion, it is evident, will consist of 3 parts, the 1st and 2d of which, n being = 4, are ob- viously attainable from the values of a and b above found in art. 9 and 16; and the 3d in series similar to those which have been given in the former part of this paper. It is evident also that, if n be = 4-, all the 3 parts of this fluent are attainable from the values of the 2 co-efficients already found, and c' would be = — 2a" + \ (b'« - b). 1 9. And in this manner may the other co-efficients, d, e, p, &c. be determined. And since the cosines of 3z, 4 2, &c. are = 4x3 — 3x, 8x4 — 8,r2 + 1, &c. respec- tively ; and since x — a ~" . , it is evident that the numerator of the frac- tion into which the fluxion in the preceding article is to be multiplied, will be always of this form, viz. p -f- qvv + rv4 -f- sv6, &c. ; from which it follows, that if the values of a', a, a, &c. corresponding to n3 n — 1, n — 2, &c. be computed, the values of c, d, e, f', and all the rest, may be found in terms of a', a, a, &c. with the co-efficients a and b. But, since the easiest method, that has come to my hands, of computing the values of c, d, e, &c. after a and b are found, is ex- plained in M. Euler's Institutiones Calculi integralis, vol. 1, p. 181, I shall not pursue this method any further ; but, having examined his process, and corrected the errors of the press which occur in it, now give the equations expressing the values of c, d, e, f, &c. which were obtained by that method. 20. For the sake of brevity, let ^- = d ; then will the general values of c, d, e, f, &c. be expressed by these equations : c = 2«A — 2«?B D = (» -f l) b — 4dc # (n + 2) c — 6dp " __ (n + 3) d — 8cte . E — - - ; F — - - , &c. n — 4 n — 5 »— 2 ' »— 3 where the law of continuation is very obvious. And the particular values of these letters, when n = 4-, 4, 4, will be as expressed in the following columns : n = ± n= 4 n = 4- 4d C = 3- B — *A 4d - B — OA —4dB -f- 10a Sd 3 d = tc y b 8d -— -C — 4-B 3 3 Sd — c — 4-b 12d E = — D — fC 12rf 12rf —-D — |C 3 J l6d Fzr — E-iD \6d — E--fD \6d — E — V » 5 x &c. &C. &C. 21. The solution of the problem being now finished, it may perhaps be satisfac- tory to the reader to see how the sums of the very slowly converging numerical VOL. LXXXVIII.] PHILOSOPHICAL TRANSACTIONS. 415 series, which arose in art. 7, 11, and 16, were obtained ; the investigations of which, because they would have detained him too long from the immediate subject of this paper, if they had been inserted in it, are given in the following appendix. An Appendix to the foregoing Paper, in which the method of obtaining the sums of the very slowly converging numerical series which are there used, and of many others of that kind which arise in the fluents of binomial surds, is explained and illustrated ; and some observations, tending to facilitate and abridge the com- putations of the co-efficients a and b, are added. 1. As the sums of the very slowly converging numerical series, which arose in several articles of the preceding paper, are not exhibited in any book that has come to my hands, and as series of that kind frequently occur, I conceive that the fol- lowing method of obtaining their sums will be acceptable to the lovers of mathe- matics in general, and particularly to those who have frequent occasion to use the sums of such series. And having observed, while considering the literal expressions in the preceding paper for the values of a and b, that others, no less accurate, might be derived from them, by which the arithmetical operations would be facili- tated and abridged, I thought these observations might likewise be acceptable to those who are engaged in the theory of astronomy, and have inserted them also in this paper; which therefore consists of 2 principal parts, the summation of the slowly converging series, and the observations now mentioned. 1 . The Summation of the slowly converging Series. — 2. But, before beginning the investigation, it will be proper to premise a few particulars, an attention to which will shorten and facilitate the operations now to be performed. lst That i-^1"^ being - iz^HjlM v 1 + ^(1-»). U _- / | vt. 1st. mat j + v(1_^} being - l+v(l _yy) X j +v(1_^> » - 4+y(i^)) ; from which it follows, that h. l. of "" ) ~~ , is = 2 h. l. 2 r. i+V(!-j») . i + vti-jy} 2dly. That the fluxion of h. l. ■ , is = — — £ — ~ — ^. For it is = ' i+VO-yy) yV(i-yy) y the fluxion of - h. l. (1+4/(1 - yy)) = -£-^ x 1+v^„y and if both numerator and denominator of this expression be multiplied by 1 —"/{\ — yy), it will become -7/—, X l^&zM, which is = — J r - I v(l — W yy * yV{i-yy) y Sdly. That the h. l. — — i . j8 therefore = f-rrf r - '..fi = /^ + * 1+V(i~yy) J yV(i-yy) J y 2.2 *~ w + 3-5*6 . 3-5-7y* &c 2.4-4^2.4.6.6^2.4.6.8.8' > 4thly. That a being put =^/(i — yy), the fluxion of i will be = l <££ + 5-i). For it will be \ - -2§- = ^ - -^1 = -y "i(1 —yy) __ - nj> . '(» - *)j _ j t_zJL _i_ njrzl\ y"— IQ y" + IQ ~ yn + IQ ' yn— Iq q ^yn + 1 f yn - l'' 5thly. That, when any quantities, as | » (~ -J- -■ -J- A) I, are circumscribed by a parallelogram, it denotes that a substitution for these quantities has been made 3V(i-yy) i 3 v 4y* ' 4~ "1 +^(1-^) 3 -;H-L-3/ 3 1 "•" 4H,L,H-V(1-^)' 4l6 PHILOSOPHICAL TRANSACTIONS. [ANNO 1798. in the same equation in which it occurs, and consequently that they are no longer to be considered as part of that equation. This I have found to be better than can- celling, as it answers the same end without obliteration. 3. As it does not seem necessary to set down the operations of computing the sums of all the series which arose in the preceding paper, I shall make choice of the summation of those which, being the most difficult, are the most proper ex- amples to illustrate this method. It is well known that the expression 2j,rs . _ • 4 , g££ , 2- %"' . 2-3-% , 2.3.5.7jy» , 2 . 3 . 5 .7.9jj/5 ^(1 _ yy) li> — ^2 "T 2 T 2.4 T 2.4.6 T 2.4.6.8 "»" 2.4.6.8. 10* &c. from which equation we have jizryyj - *yy -yy — 4 - 4.6 + 4.6. 8 + 4.6.8.io' *c- ^^ the fluents of the terms on 2/ the 1 st side are | 4. _L _i L [ ~ V 2yy on the 2d side, the fluents are |^| + 4'g'g^ + ^[e'l.io^ &c* And' to find whether these 2 expressions are = each other, or have a constant difference, we may compute their numerical values, y being put = any small simple fraction, such as -rV> i-5-5-> or \ o'oo? either of which values of y is a very convenient one for the purpose. But an easier method to discover the constant quantities which lie con- cealed in some of the terms on the first side, is to convert that side into series, by the binomial theorem; which will then be as follows: — V(l — yy) , _4 1 , -* 1 , 1 1 ,.2 4. 5 -/ &r 2^ — Try Ttj/ TttT -r^y n~ -a-mry 9 o"" ~3\/(i —yy) __ 3_2 1 3 j_ 3 7,2 1 9_w4 fc.c 4— — — t# T t T- ttt3/ T Try J «C. + 4H- L. i+^.yy) = -4H.L.2+-ry/ + -rf-sy, &C. The sum is = * * + TV — iH- L- 2> + iVy* + tA&^S &c which evi- dently differs from the series on the 2d side by the constant quantity -fo — ^h. l. 2. We therefore have, by subtracting this constant quantity from the first side, jv(j -yy) 3V(i-yy) , 2 } 2y C " 4.6.8.' ~ 4.6.8.10.6 "*" 3. 5.7. 9- Hj/7 4.6.8.10.12. 8* &C. the sake of brevity, there will be y 2yb ' 2y3 \6y l6 And, if this equation be put into fluxions, and a be written for v/(l — yy), for 5 ■ 9 j_ _3_ _ J i 3m __ 3wy Q 2J/4 4^y " 6 T" 4y4 T 40 f _4_ j6_f 9«4 4vv / 4j/y $& ■ 2y< j3_ 4.6.8.4 + 4.6.8.10.6 ^ + 4 6.8.10.12.8 &C. And this equation, more concisely expressed and divided by y, gives v2y ' 4_y5 + (— -- 3uy 4yi ' Q 5 5 v • i6j/s i6y y ~ 3.5.7. 3yy , 3.5.7. 9-5yy* T 3.5.7.9.1 i.7jy» - 4.6.8.4 ' 4.6.8.10.6 ' 4.6.8.10.12.8 Now the fluent of the series on the 2d side of this equation is found, by the methods which have been long known, to be 3.5.7.3j/y , 3.5.7.9-5y4 , 3. 5. 7. 9. 11. 7y6 \ A (^ o in in o £> &c. and the fluent of the terms on 4.6.8.4.2 ' 4.6.8.10.6.4 ' 4.6.8.10.12.8.6' the first side will be very easily obtained, by the following assumption, and attention to what was shown in art. 2 of this paper. For the fluent of the terms on the first side of this equation, assume + (£ + £ + £)* + "(£ + *) P -|f- i% t-j [- s h. l. y ; then will the fluxion of this expression be — 6a 46 2c f y y 5a 3b c_ T f yl y T y% y. , (z^p _ i? __ §r _i_ i. + »(£ + s) i Q 2fuy f 4q 2r _£_■> -4-4 y, which being put = the first side of the foregoing equation, there will arise as many simple equations for determining the co-efficients a, b, c, &c. as there are letters of that kind in the assumed fluent, from which their values will easily be found. The variable part therefore, of the fluent of the first side of the above equation, is ,— 5 7 5 x . / 3 . a (- \6yy' \ K8yy I jj \ t j _j ^_ 12v° ' 8y4 32jcy" 16^' ' " y8yy ! 16' ' |%* n 8y* " 3f#" N°W' t0 disc°ver the constant quantities which lie concealed in this expression, we must proceed as above in art. 3, whence is obtained, VOL. XVIII, 3 H 418 PHILOSOPHICAL TRANSACTIONS. [ANNO 17Q8. H,L* l (8i"l6J(=i6H'L,a( 3.5.7.3 3 . 5 ._7 . 9_. ,5_ 3.5.7.9.11.7 1 A_l_£_ X —iZlV" 4. Z£.( 4.6.8.4. 8~»~4 . 6 .8 .10 .6 . 4 ' 4 .~6 . 8 . 10 . 12 . 8 . 6* *"l2'8 32 192 '192' &c. which is the value of another series of the preceding paper. 5. If the last literal equation be divided by y, and ^pjJLipL = l^l be then taken from both sides, we shall have ,^_5 _ 7__ _5_^ , (3_ M2^7 "" 12/ l6y*' ' U ^8/ , _5 , _3_ 1 67 "' 12m7 "V RuS 4.6.8.4.2 512 123/7 ' 8/ 32/ 1923/ 512 3 . 5 . 7 . 9 ■ 5/ , 3.5.7.9.11 .7/ , 3 . 5 . 7 . 9 . 11 . 13 . 9/ - 1 • , 4 . 6 . 8 . 10 . 6 . 4 "^ 4 . 6 . 8 . 10 . 12 . 8 . 6 "*" 4 . 6 . 8 . 10 . 12 . 14 . 10 . 8» wniCtl equation, in fluxions, gives q V12y9 ' 12/ 48/ l6/' •* v8/ ' 163/*' "■"■^ 12/ 8/ 32/ ' 192/ 512' ~ 3.5.7.9 -5.3jy , 3.5.7.9.11 .7.5}? 3.5 .7-9.11. 13. 9. 7jy5 « 4 . 6 . 8 . 10 . 6. 4 "*" 4 . 6 . 8 . 10 . 12 . 8. 6 " "*" 4 . 6 I 8 . 10 . 12 . ,14 . 10 . 8 ' Now the fluent of the fluxionary series on the 2d side of the equation being obviously thP spHp* 3 . 5 . 7 . 9 . 5 . 3yy , 3.5.7.9.11.7.5/ 3.5.7.9.11-13.9.7/ inc &cnc& 4#6#8>10#6.4i2-r4.6.8.10.i2.8.6.4"r 4.6.8.10.12.14.10.8.6' &c. we are next to take the fluent of the expression on the first side, and to correct it, that it may be = this series; which may be done as follows: For the fluent sought, assume z^ + j.+ ^+j,) +«($+%+>>) + f< + j; + j.+^ + '»-^> and take the fluxion of this expression ; then these fluxionary terms being put = to those on the first side of the preceding equation, there will arise several equa- tions for determining the values of the letters, a, b, c, &c. and then the assumed fluent becomes, ( -35 95 75 105 . . 9 , _5 , 105 > ° *8 . 12/ 12 . l6y6 4 . 8 . 8/ ~~ 8 . 8 . 83/5/ "*~ U ^32/ ■" 323/3/ "*" 8 . 8 . 8' -I „ + -7T- * — - — - — — - *, which may be corrected in the ~ 8 . 12/ l6y« 4.8. 123/3/ J manner shown in the 2 preceding articles, when it becomes ( - 35 95 75 105 >, , (9_i__A ■ 105 v tt ^8 . 12/ 12 . 16/ l6 . 16/ 8.8. 83/3/ "" U ^32/ -+~ 32yy "*~ 8 . 8~ . 8' 35 5 # 37 1023 _ , + 8~T278 + 16/ 4.8. 12^/v 4096 "~" ttie SenCS 3 . 5 . 7 . 9 . 5 . 33/3/ , 3.5. 7.9. 11-7. 5y^_ , 3 . 5 . 7 . 9 - 11 • 13 ■ 9 • 7/ & 4 . 6 . 8 . 10 . 6 . 4 . 2 ' 4 . 6 . 8 . 10 . 12 . 8 . 6 . 4 "* 4 . 6 . 8 . 10 . 12 . 14 . 10 . 8 . 6' which, when y = 1 , becomes 9 ,5 .105 H.L.2.(- +- +— 8 8)| ^ .35 .5 37 1023 f — i "• 8.12M6 4.8.12 4096 J '2288 ' 512 VOL. LXXXVIII.] PHILOSOPHICAL TRANSACTIONS. 4\Q 3.5.7.9-5.3 , 3 . 5 .7-9. H-7.5 3 . 5 . 7 . 9 • 11 . 13 . 9 • 7 « = 4 . 6 . 8 . 10 . '6 . 4 . 2 ~*~ 4 . 6 . 8 . 10 . 12 . 8 . 6 . 4 ' 4 . 6 . 8 . 10 . 12 . 14 . 10 . 8 . 6y which is the value of another series of the foregoing paper. II. Observations, tending to facilitate and abridge the numerical computations of a. and b in the preceding paper. — 6. The radical factor a/(1 — cc), in the literal expressions of the values of a and b, may be taken away, by multiplying the other factors by its equivalent 1 — — — - - — -g, &c. in consequence of which, other expressions will be obtained, better adapted to the purpose of numerical calcula- tion. This will appear by the following operations. The product of >/(l — cc) X the other factor in the expression of the value of a, in art. 9 of the preceding 22 paper, viz. — + a + ^cc + vc4, will give - + e + fee + gc4, &c. where, e,f, and g, are = a — 1, ^ — 4-A — ^-, and t — 4-//, — -fA — i, respectively; in numbers = 0-1931472, 0-1036802, and 0-0687064, respectively. And this expression, which is evidently more simple than the former, is somewhat nearer than that to the value of the whole series. 7. In like manner, the product of the 2 factors in the value of a', in art. 13, viz.— + — + a' + pec -f /c4, will be = — + - + h -f- ice + kc\ &c. which expression also is more simple than that from which it is derived, while its accuracy is not less, as is pretty evident on inspection. And that the numerical values of ht i, and k, are very easily attainable from the values of a', (/, and /, given above in art. 3, 4, and 5, of this paper, is very obvious. 8. And the product of the 2 factors in the value of b, in art. 16, may also be exchanged for a more convenient expression, by a like process. viz. p + ccc + tc4 X 1 — - — —, &c. = p -f lec + mc4, &c. which expression also is more accurate than that from which it is derived, as well as more simple. 9. The numerical calculation of the other member also, in which % enters, may be facilitated and abridged, by the following considerations. If c be put for the sine of an angle, radius being 1, then will J + \/(l — cc) be the versed sine of the supplement of that angle, and jr~z — \ w^ ^e = ^e tangent of half that angle; from which it follows, that the reciprocal of this quantity, viz. 1 + ^ *~ ccl9 is = the co-tangent of half the angle of which the sine is c. The common loga- rithm of may therefore be taken out from a table of common loga- rithms, and then converted into an hyperbolic logarithm, by table 37 of Dodson's Calculator, or by table 7 of Dr. Hutton's Logarithms. 10. An expression of this kind, - ~ rcc , when c is the only variable quantity, consisting of several figures, and r and s are likewise long numbers, will be much better adapted to the use of logarithms, when put in this form, - X u. *$ be- cause the multiplications of r and s into cc, or additions of their logarithms and 3 H 2 420 PHILOSOPHICAL TRANSACTIONS. [ANNO 1798. taking out two numbers, are by this means exchanged for the addition of the con- stant logarithm of - : the quotients - and q-, once found, being constant numbers. 8 — 2cc Thus, the numerical value of even - __ . , where r and s are single figures, is more easily obtained by — X ng-*-r ;> tnan by tne former expression. 11. But it will appear on trial, that the arithmetical value of any 3 terms, p' + q'cc + r'c4, in -which p', q\ and r, are constant quantities, and cc consists of 5 or 6 places of figures, may, in general, be more easily obtained by logarithms, than the arithmetical value of - X r— -jl — • And since the difference of the values of s q -i- s ±cc these 2 expressions is inconsiderable in the present case, I shall make no further use of the fractional expression ; but observe, that the logarithm of q'cc, in the other expression, being found, the logarithm of r'c4 will be had, by adding to it the logarithm of -r cc; for q'cc X ~gr cc = r'c*. And, since the logarithms of the numbers which stand in the places of q' and - may be taken out and reserved for use, and the logarithms of cc and a, once found, will serve for all the terms in which these quantities occur, it will appear by an example, that neither many logarithms, nor many numbers corresponding to logarithms, need be taken out of other tables, in computing the value of a or b. 12. It will now be proper, since the literal expressions of the values of a and b have been exchanged for others which are more convenient, to bring the new equa- tions together in one view, and then give an example of the numerical calculations by them. It appears, by art. 9, 10, 13, 16, and 1 7 of the preceding paper, and 6, 7, and 8 of this, that 1. A = 4r + e+fcc+ gc* 3.5 * (a + 6)1 ) + a+ :L ace + ~ ac4 8 '8.8 , 1 \ — -| r- h 4- ice -f he4, 1+ *'= r- V V- CC T 3 , 3 5 3.5.21 sr(a + b)v 4.12.32 2a *i p -\- lec -{- mc4 b *b{a + b)i 1 _L. 2a + ±<*CC -f ~-q uc\ 4. B'=f(A'a-A). In which equations, the values of the coefficients are as follow: e — 0-1931472, h = 00823604, p = 1*3862944, /= 0-1036802, i = 0*0551502, / = 03465736, g = 0-0687064, k = 0*0408309, m = 0* 1793226. The constant numbers which will be wanted, in computing the arithmetical values of a and b, are those denoted by e, h, and p, which are given in the preceding article. Mr. H. then sets down the work of an example, in a very neat manner, viz. for the 2 planets Venus and the earth. VOL. LXXXVIII.] PHILOSOPHICAL TRANSACTIONS. 421 XXIII. Of a Substance found in a Clay-pit; and of the Effect of the Mere of Diss, on various Substances immersed in it. By Mr. Benj. Wiseman, of Diss, Norfolk. Communicated by John Frere, Esq., F. R. S. With an Analysis of the Water of the said Mere. By Charles Hatchett, Esq., F. R. S. p. 567. This substance was found near Diss, in a body of clay, from 5 to 8 feet below the surface of the soil. All the pieces lay nearly in an horizontal direction; and varied in size, from 2 or 3 oz., to as many lb. The colour of the substance, when taken fresh from the clay- pit, was like that of chocolate; it cuts easily, and has the striated appearance of rotten wood. The pieces were of no particular form ; in general, they were broad and flat, but I do not recollect to have met with a piece that was more than 2 inches in thickness: it breaks into laminae, be- tween which are the remains of various kinds of shells. The specific gravity of this substance, dried in the shade, is 1.588; it burns freely, giving out a great quantity of smoke, with a strong sulphureous smell. By a chemical analysis, which I cannot consider as very accurate, 100 gr. appear to contain, Of inflammable matter, including the small quantity of water contained in the substance 41.3 grs. Of mild calcareous earth 20.0 Of iron 2.0 Of earth, that appears to be silex 36.7 100 On the effect of the Mere of Diss, on various substances. Observing several years ago, that flint stones taken out of the Mere of Diss were incrusted with a metallic stain, I was induced to make some experiments, in order to discover the nature or composition of this metallic substance. Nitrous acid readily removes it, dissolving a part, and leaving a yellowish powder, which, washed and filtered, was found to be sulphur. Vegetable fixed alkali precipitated from the nitrous acid a ferruginous coloured powder, which was iron. With a view to determine what length of time was necessary for the formation of this metallic stain on flint stones, or other substances, I inclosed in a brass wire net the following articles: flint stones, calcareous spar, common writing slate, a piece of common white stone ware, and a piece of black Wedgwood-pot- tery. After remaining in the water from the summer of 17 92 to August, 1795, the flints and Wedgwood-ware had acquired the metallic stain in a slight degree, and the slate had assumed a rust colour; the other substances appeared not to be at all altered. I was greatly surprized to find the copper wire that held the net, surrounded with a metallic coating of a considerable thickness; it was of a deep lead colour, and of a granulated texture. When taken from the wire, and ground in a mortar, it had a black appearance, interspersed with very hard shining parti- cles. The wire was evidently eroded, and this substance deposited in the place of the copper that was decomposed, somewhat similar to the decomposition of iron in cupreous waters. By repeated chemical analysis of this substance, 100 gr. contain, of copper, 70; of sulphur, 16.6; of iron, 13.3 gr, 422 PHILOSOPHICAL TRANSACTIONS. [~ANNO *798. I have never met with an account of the decomposition of copper, in waters impregnated with iron, in any chemical work; and as iron appears to have a greater affinity to the vitriolic acid than copper has, as is constantly evinced in the neigh- bourhood of copper mines, it appears an anomaly in chemistry, that I am not adept enough in the science to account for. [The President and Council, thinking the effects of the water of Diss Mere deserving of further in- quiry, desired Mr. Wiseman would send some of the said water, for the purpose of examination. Mr. Wiseman accordingly sent a quantity of the water, accompanied by the other substances de- scribed in the following letter to the President, dated Diss, May 29, 1798] " As the Society have expressed a wish, through Mr, Frere, to have some of the water in which the copper wire was deposited, which Mr. Frere, at my request, laid before the Society, I have sent 2 gallons of the water of Diss Mere, (N° J), with a small quantity of copper cuttings, (N° 2), which laid in the same water, a few feet from the side, and 6 feet in depth, from the 7th of February, 1797,' to the 20th of the present month, May, 1798. The pieces of copper, when laid in, weighed 3051 gr.; when they were taken out, and washed from the mud that lightly adhered to them, preserving and weighing the scaly matter that came of£ they weighed 2944 grs., indicating a loss of 107gr. Examining the pieces of copper, the same evening they were taken out of the water, I observed a number oY small crystals formed on some of them, in the form of pyramids joined at their bases; these crystals lost their shining appearance, by the evaporation of the water of crystallization, in the warmth of the succeeding day. Whether they will be preserved in a journey of nearly 100 miles, is perhaps doubtful. N° 3 contains 2 pieces of copper, on which the crystals were most abundant. N° 4 contains a small quantity of the substance formed on the copper, that came off in washing and in weighing it. The town of Diss is principally situated on the n.n.e. and e. sides of this piece of water. The land runs pretty steep on the w. and n. of it, to the height of 40 or 50 feet: on the s.e., the ground comes within a few feet of the level of it. The soil of the upper part of the town is a stiff blue clay; that of the lower part, to the s.e., a black sand, beneath which it is a moor. The water in the higher parts of the town is good; in the lower parts, it is a chalybeate, of which a specimen is sent, (N° 5). N° 6 contains a quantity of flint stones, taken from the s.e. side of the Mere, where the water is shallow; many of which are strongly marked with the metallic stain, which they acquire by lying in this water a few years. The Mere contains about 8 acres, and is of various depths, to 24 feet: from its situation with respect to the town, it may naturally be supposed to contain a vast quantity of mud, as it has received the silt of the streets for ages. In summer, the water turns green ; and the vegetable matter that swims on its surface, when exposed to the rays of the sun, affords vast quantities of oxygen gas. I cannot help considering this process as having a considerable agency in the corrosion, and in the formation of the metallic crust on the copper deposited in this water. Some of this vegetable matter will be found, in the water sent to the Society," VOL. LXXXVIir.] PHILOSOPHICAL TRANSACTIONS. 423 [The water, and other substances described in the foregoing letter, were delivered to Mr. Hatchett, who had been previously requested, by the President and Council, to examine them. The result of his examination is as follows :] Analysis of the Water of the Mere of Diss. By Chas. Hatchett, Esq. The substances sent by Mr. Wiseman are as follow: Some copper wire, with a blackish grey incrustation. Water from Diss Mere, (marked N° l). Copper cuttings, covered with a blackish crust, similar to that on the copper wire, (marked N° 2). Some cuttings similar to those above-mentioned (marked N° 3). The paper, N° 4, contained some of the black crust, detached from the cuttings. N° 5, a quart bottle, containing some water from the lower part of the town of Diss, and called, by Mr. Wiseman, a chalybeate water. N° 6, some flints, taken from the s.e. side of the Mere, where the water is shallow, and having, as Mr. Wiseman terms it, a metallic stain. My first experiments were made on the incrustation of the copper wire, men- tioned in Mr. Wiseman's first letter. This incrustation was easily detached from the wire, and being reduced to powder, was digested with nitro-muriatic acid, in a gentle heat: a green solution was formed, and there remained a residuum, of a pale yellow, which proved to be sulphur. The solution being diluted with 1 parts of distilled water, was supersaturated with pure ammonia, by which, a few brown flocculi of iron were precipitated. The supernatant liquor was blue; and being evaporated, and re- dissolved by sulphuric acid, the whole was precipitated by a plate of polished iron, in the state of metallic copper. The component parts of this coating were therefore copper, and a very small portion of iron combined with sulphur. I could not extend these experiments, as the whole quantity of the coating that I was able to collect, amounted only to 3-i-gr.* The next experiments were made on the black crust of N° 2, 3, and 4. This I found to be exactly the same as that formed on the copper wire; viz. it consisted of copper combined with sulphur, and a very small portion of iron. I next examined the water of Diss Mere, (N° l) and I was at length led on, step by step, to make a regular analysis of the fixed ingredients. Before making the analysis, I examined this water with certain re-agents, and remarked the following properties. 1. The water of Diss Mere has a yellowish tinge, and the flavour is rather saline; but it has not any perceptible odour. 1. Prussiate of pot-ash did not produce any effect. 3. Acetite of lead produced a slight white precipitate. 4. Nitrate of silver formed one, very copious. 5. Tincture of galls had not any * The copper w>re, when the coating was removed, was perfectly flexible, and the surface did not appear unequal or corroded : this is commonly the case under such circumstances ; for, when sulphur has combined superficially with a metal, the compound is observed to separate easily, so as to leave the metal underneath not injured in quality, and very little, if at all, affected in appearance. Those who diminish silver coin, make use of the following method. They expose the coin to the fumes of burn- ing sulphur, by which a black crust of sulphurated silver is soon formed, which, by a slight but quick blow, comes off like a scale, leaving the coin so little affected, that the operation may sometimes be repeated twice or thrice, without much hazard of detection, if the coin has a bold impression.— Orig. 424 PHILOSOPHICAL TRANSACTIONS. [ANNO 1798. effect. 6. Muriate of barytes caused a slight precipitate. 7. Ammonia, pot-ash, and oxalic acid, severally produced precipitates, when added to different portions of this water. Analysis. — a. 300 cubic inches of the water, by a gentle evaporation, left a pale brown scaly sub- stance, which weighed 58 gr. b. These 58 gr. were digested in alcohol, without heat, during 24 hours, and afforded a solution, which, by evaporation, yielded muriate of lime, slighdy tinged by marshy ex- tract, 18 gr. c. 6 oz. of distilled water were then poured on the residuum, and, with repeated stirring, remained during 24 hours. By evaporation this afforded muriate of soda, with a very small portion of sulphate of soda; in all, 10 gr. d. What remained was boiled in 800 parts of distilled water j and the solution, being evaporated, left of selenite 1.70 gr. e. The undissolved portion now weighed 25 gr., and was digested with diluted muriatic acid : a great part was dissolved, with much effervescence, and, being filtrated, afforded, by ammonia, of alumina 1.50 gr. From this I afterwards separated a very minute quantity of iron, by means of prussiate of pot-ash. f. Carbonate of soda was then added to the liquor, and precipitated carbonate of lime 21 gr. a. The insoluble residuum weighed 3.50 gr.j and proved to be principally carbon, produced by decomposed vegetable matter, with a very small quantity of siliceous earth. The result of this analysis was, therefore, Grains. b. Muriate of lime 18 c. Muriate of soda, with a very small portion of sulphate of soda 10 d. Selenite X 70 e. Alumina, with a portion of iron too small to be estimated 1 50 f. Carbonate of lime 21 6. Carbon, with a littie siliceous earth 3 50 55 70 Loss 2 30 58 0 It is worthy of notice, that the iron present was in so very small a quantity, as not to be detected by any test, till it had been separated in conjunction with the alumina. • The water N° 5, from Mr. Wiseman's account, does not appear to have been concerned in producing the effects which he has observed, and the quantity was too small to be subjected to a regular analysis, I noted however what follows: 1. It has a very strong hepatic flavour and smell. 1. A plate of polished silver, put into it, became black in a few hours. 3. It became faintly bluish with prussiate of pot- ash, after standing 5 or 6 hours. 4. Tincture of galls produced a faint purple cloud. 5. Solution of acetite of lead afforded a brown precipitate. 6. Nitrate of silver produced the same. 7- Pot-ash, and ammonia, caused a precipitate; but that of the former was the most copious. 8. Oxalic acid produced a precipitate. 9. Muriate of barytes had also a slight effect. The water N° 5 cannot therefore be considered as a chalybeate, the quantity of iron contained in it being scarcely perceptible; but it appears to be a water containing some hepatic gas, together with substances similar to those contained in N° 1. From the above experiments it is evident, that the water N° 1 does not contain any of the component parts of the crust formed on the copper wire and cuttings, though it is certain that the incrustation took place during the immersion of those VOL. LXXXVIII.] PHILOSOPHICAL TRANSACTIONS. 425 bodies; but before mentioning my ideas on this subject, I shall give an account of some experiments made on the flints, N° 6. These were coated with a yellowish shining substance, which appeared to be pyrites; and as the flints could not have contributed any metallic substance to form this coating, I was enabled by their means to ascertain, whether the copper of the crust, formed on the wire and cuttings, had been furnished by the pieces of copper, or by any thing in the vicinity of the water. 1 . I poured nitro-muriatic acid on some of the flints, in a matrass, so as completely to cover them. The coating was rapidly dissolved, with much effervescence; and when the flints appeared perfectly uncoated, and in their usual state, I decanted the liquor. 2. A yellow matter subsided, which proved to be sulphur. 3. Prus- siate of pot-ash produced Prussian blue; and the remaining part of the solution, being supersaturated with ammonia, afforded an ochraceous precipitate of iron. The supernatant liquor did not become blue, as when copper is present, nor was the smallest trace of it afforded by evaporation. Martial pyrites is therefore the only substance deposited on bodies immersed in the water of Diss Mere; and the copper of the crust, formed on the wire and cuttings, was furnished by those bodies. It is proved by the analysis, that the water of Diss Mere does not hold in solu- tion any sulphur, and scarcely any iron ; it has not therefore been concerned in forming the pyrites ; but it appears that the pyritieal matter is formed in the mud and filth of the Mere ; for Mr. Wiseman says in his letter, that " the Mere has received the silt of the streets for ages." Now it is a well-known fact, that sulphur is continually formed, or rather liberated, from putrefying animal and vegetable matter, in common sewers, public ditches, houses of office, &c. &c; and this most probably has been the case at Diss. And, if sulphur, thus formed, should meet with silver, copper, or iron, it will combine with them, unless the latter should be previously oxidated. The sulphur has therefore, in the present case, met with iron, in, or approaching, the metallic state, and has formed pyrites; which, while in a minutely divided state, or progressively during formation, has been deposited on bodies, such as the flints, when in contact with the mud. But an excess of sulphur appears to be present; for when copper is put into the Mere, the sulphur readily combines with it; and at the same time a small portion of iron appears to unite with the compound of copper and sulphur, possibly by the mere mechanical act of precipitation. The incrustation on the copper wire and cuttings is, in every property, similar to that rare species of copper ore, called by the Germans Kupfer schwartze, (cuprum ochraceum nigrum) ; and I consider it as absolutely the same. In respect to the martial pyrites on the flints, there can be no hesitation ; and as in these 2 instances there were evident proofs of the recent formation of ores in the humid way, I was desirous to ascertain the effect on silver. I therefore wrote to Mr. Wiseman, to request that he would take the trouble to make the experiment: and received from him the following answer, dated Diss, 8th Sept. 1798, accompanied by the specimens. VOL. XVIII. 3 I 426 PHILOSOPHICAL TRANSACTIONS. [ANNO 1 798. " Sir. — Immediately on the receipt of your letter, (27th July) I laid some silver plate, and silver wire, into the Mere; the whole weighed 235.6 gr. I took it out on Thursday last, (Sept. 6th) and, after cleaning it carefully from mud and weeds, I find it weighs 242.8 gr.; an increase of 7.2 gr. The silver plate you will find much tarnished, in some parts almost black; the wire is in many places fairly in- crusted, which crust on the pressure of the fingers, comes off in thin scales. The whole appearance of the silver strongly indicates the presence of sulphur, which I have no doubt abounds in every part of the Mere. The peculiar smell of the mud gives reason to suppose, that a great deal of hepatic air is produced; which probably uniting with the iron held in solution in the water of the Mere, may account for the martial pyrites found on the flints. By what affinity the copper wire, laid in this water, is attacked, I am not chemist enough to determine. I have begun a set of experiments, with the view of producing the same effects on copper wire by artificial means; but whether I shall succeed, I am not able at present to say. Benj. Wiseman." p. s. — By experiments I have lately made, I find hepatic gas precipitates carbonate of iron in the form of a black flocculent matter: 71 parts of which are iron, and 29 sulphur. The silver plate I found, as Mr. Wiseman has mentioned, much tarnished, and in many places almost black, but I could not detach any part of it. I succeeded better with the wire, and collected a small portion of a black scaly substance, which, as far as the smallness of the quantity would allow it to be ascertained, was sul- phuret of silver; and was similar, in every respect, to the sulphurated or vitreous ore of silver, called by the Germans glasertz. This effect on the silver was to be expected; and I recollect to have read, not many months ago, in one of the foreign journals, that Mr. Proust had examined an incrustation, of a dark grey colour, formed in the course of a very long time, on some silver images, in a church at, I believe, Seville. This incrustation he found to be a compound of silver with sulphur, or, in other words, vitreous silver ore. The same principle is the cause of the tarnish which silver plate contracts with so much ease, particularly in great cities; for this tarnish is principally a commencement of mineralization on the sur- face, produced by the sulphureous and hepatic vapours dispersed throughout the atmosphere, in such places. To Mr. Wiseman's observations we are much indebted, as they make known the recent and daily formation of martial pyrites, and other ores, under certain circum- stances. It is not to be supposed that such effects are local, or peculiar to Diss Mere; on the contrary, there is reason to believe that similar effects, on a larger scale, have been, and are now, daily produced in many places. The pyrites in coal mines have probably in great measure thus originated. The pyritical wood also may thus have been produced; and by the subsequent loss of sulphur, and oxida- tion of the iron, this pyritical wood appears to have formed the wood-like iron ore which is found in many parts, and particularly in the mines on the river Jenisei, VOL. LXXXVIII.] PHILOSOPHICAL TRANSACTIONS. 42/ in Siberia. In short, when the extensive influence of pyrites in the mineral king- dom, caused by the numerous modifications of it, in the way of composition and decomposition, is considered, every thing which reflects light on its formation be- comes interesting; and I cannot but regard as such, the effects which Mr. Wise- man has observed in the Mere of Diss. Charles Hatchett. XXIV. A Catalogue of Sanscrita Manuscripts, presented to the R. S. by Sir Wm. and Lady Jones. By Charles fVilkins, Esq. F. R. S. p. 582. 1. a. Maha-bharata.* A poem in 18 books, exclusive of the part called Raghuvansa; the whole at- tributed to Crishna Dwaipayana Vyasa; with copious notes by Nila-canta. This stupendous work, when perfect, contains upwards of 100,000 metrical verses. The main subject is the history of the race of Bharata, one of the ancient kings of India, from whom that country is said to have derived the name of Bharata-varsha ; and more particularly that of 2 of its collateral branches, distinguished by the patrony- mics, the Cauravas and the Pauravas, so denominated from 2 of their ancestors, Curu and Puru, and of their bloody contentions for the sovereignty of Bharata-varsha, the only general name by which the Aborigines know the country we call India, and the Arabs and Persians Hind and Hindostan. But, be- sides the main story, a great variety of other subjects is treated of, by way of introduction and episode. The part entitled Raghu-vansa, contains a distinct history of the race of Crishna. The Maha-bharata is so very popular throughout the East, that it has been translated into most of its numerous dialects; and there is an abridgment of it in the Persian language, several copies of which are to be found in our public libraries. The Gita, which has appeared in an English dress, forms part of this work; but, as it con- tains doctrines thought too sublime for the vulgar, it is often left out of the text, as happens to be the case in this copy. Its place is in the 6th book, called Bhishma-parva. This copy is written in the cha- racter which, by way of pre-eminence, is called Devanagari. Ly J. 1. b. Ditto. Another copy, without notes, written in the character peculiar to the province of Bengal, in which the Brahmans of that country are wont to transcribe all their Sanscrita books. Most of the al- phabets of India, though they differ very much in the shape of their letters, agree in their number and powers, and are capable of expressing the Sanscrita, as well as their own particular language. This copy contains the Gita, in its proper place. Ly J. 2. a. Ramayana. The adventures of Rama, a poem in 7 books, with notes, in the Devanagari cha- racter. There are several works with the same title, but this, written by Valmici, is the most esteemed. The subject of all the Ramayanas is the same : the popular story of Rama, surnamed Dasarathi, sup- posed to be an incarnation of the god Vishnu, and his wonderful exploits to recover his beloved Sita out of the hands of Ravana, the gigantic tyrant of Lanca. 1/ J. 2. b. Ditto. Another copy, in the Bengal character, without notes, by Valmici. 1/ J. 2. c. Ditto. A very fine copy, in the Devanagari character, without notes; but unfortunately not finished, the writer having been reduced to a state of insanity, by habitual intoxication. S. W, J~. 3. a. Sri Bhagavata. A poem in 12 books, attributed to Crishna Dwaipayana Vyasa, the reputed author of the Maha-bharata, and many other works ; with notes by Sridhara Swami. Devanagari cha- racter. It is to be found in most of the vulgar dialects of India, and in the Persian language. It has also appeared, in a very imperfect and abridged form, in French, under the title of Bagavadam, trans- lated from the Tamul version. The chief subject of the Bhagavata is the life of Crishna; but, being one of that species of composition which is called Purana, it necessarily comprises 5 subjects, including that which may be considered the chief. The Brahmans, in their books, define a Purana to be " a poem treating of 5 subjects: primary creation, or creation of matter in the abstract; secondary creation, or the production of the subordinate beings, both spiritual and material ; chronological account of their grand periods of time, called Manwantaras ; genealogical rise of families, particularly of those who * The Sanscrita words are spelt according to the method practised by Six William Jones, in his works. — Orig. 3 I 2 428 PHILOSOPHICAL TRANSACTIONS. [ANNO 1798. have reigned in India j and lastly a history of the lives of particular families." There are many copies of this work in England. Ly J. 3. b. Ditto. Another copy, in the Bengal character, without notes. Ly J. 3. c. Ditto. Another copy, on palm leaves, in the Bengal character. S. W. J. 4. Agni Purana. This work, feigned to have been delivered by Agni, the god of fire, contains a variety of subjects, and seems to have been intended as an epitome of Hindu learning. The poem opens with a short account of several incarnations of Vishnu j particularly in the persons of Rama, whose ex- ploits are the theme of the Ramayana, and of Crishna, the material offspring of Vasudeva. Then follows a history of the creacion ; a tedious dissertation on the worship of the gods, with a description of their images, and directions for constructing and setting them up j a concise description of the earth, and of those places which are esteemed holy, with the forms of worship to be observed at them} a treatise on astronomy, or rather astrology j a variety of incantations, charms, and spells, for every oc- casion} computation of the periods called Manwantarasj a description of the several religious modes of life, called A'srama, and the duties to be performed in each of them respectively } rules for doing penance} feasts and fasts to be observed throughout the yearj rules for bestowing charity} a dissertation on the great advantages to be derived from the mystic character OM ! with a hymn to Vasishta. The next subject relates to the office and duties of princes } under which head are given rules for knowing the qualities of men and women} for choosing arms and ensigns of royalty} for the choice of precious stones } which are followed by a treatise on the art of war, the greatest part of which is wanting in this copy. The next head treats of worldly transactions between man and man, in buying and selling, bor- rowing and lending, giving and receiving, &c. &c. and the laws respecting them. Then follow certain ordinances, according to the Veda, respecting means of security from misfortunes, &c. and for the worship of the gods. Lists of the 2 races of kings, called the Suryavansa, and the Chandravansaj of the family of Yadu, and of Crishna} with a short history of the 12 years war, described in the Maha-bharata. A treatise on the art of healing, as applicable to man and beast, with rules for the ma- nagement of elephants, horses, and cows} charms and spells for curing various disorders} and the mode of worshipping certain divinities. On the letters of the Sanscrita alphabet } on the ornaments of speech, as applicable to prose, verse, and the drama} on the mystic signification of the single letters of the Sanscrita alphabet; a grammar of the Sanscrita language, and a short vocabulary. The work is divided into 353 short chapters, and is written in the Bengal character. Ly. J. 5. Calica Purana. A mythological history of the goddess Cali, in verse, and her adventures under various names and characters ; a very curious and entertaining work, including by way of episode, several beautiful allegories, particularly one founded on the motions of the moon. There seems to be something wanting at the end. Bengal character, without notes. Ly. J. 6. a. Vayu Purana. This work, attributed to Vayu the god of wind, contains, among a variety of other curious subjects, a very circumstantial detail of the creation of all things celestial and terrestrial, with the genealogy of the first inhabitants } a chronological account of the grand periods called Man- wantaras, Calpas, &c.} a description of the earth, as divided into Dwipas, Varshas, &c, with its di- mensions in Yojanas ; and also of the other planets, and fixed stars, and their relative distances, circum- ferences of orbits, &c. &c. Written in the Devanagari character. I/. J. 6. b. Ditto. A duplicate in the Dc vanagari character. U. J. 7. Vrihan Naradiya Purana. This poem, feigned to have been delivered to Sanatcumara, by the in- spired Narada, like others of the Puranas, opens with chaos and creation j but it treats principally of the unity of God, under the title of Main Vishnu } arguing, that all other gods are but emblems of his works, and the goddesses, of his powers} and that the worshipping of either of the triad, creator, preserver, or destroyer, is, in effect, the worshipping of him. The book concludes with rules for the several tribes, in their spiritual and temporal conduct through life. It is a new copy, in the Bengal character, and, for a new copy, remarkably correct. V. J. 8. Naradiya Purana. This poem treats principally on the worship of Vishnu, as practised by Ruk- mingada, one of their ancient kings. Devanagari character. S. W. J. Q. a. Bhavishyottara Purana. The 2d and only remaining part. The subject is confined to religious ceremonies. Devanagari character. S. W. J. VOL. LXXXV1II.] PHILOSOPHICAL TRANSACTIONS. 429 g. b. Ditto. With an index. Devanagari character. U. J. 10. Gita-govinda. A beautiful and very popular poem, by Jayadeva, on Crishna, and his youthful adventures. Bengal character. 1/. J. 11. a. Curaara Sambhava. An epic poem on the birth of Cartica, with notes, by Calidasa. Deva- nagari character. The notes are separate. 1/ J. 11. b. Ditto. A duplicate of the text only, in the Bengal character. Ly J. 12. Naishadha. The adventures of Nala ; a poem, with notes. Bengal character. 1/ J. 13. Bhatti. A popular heroic poem, in the Bengal character. 1/ J. 14. Raghu-vansa. The race of Crishna, a poem by Calidas, with notes. Devanagari character. I/J. 15. Vrihatcatha. Tales in verse, by Somadeva. Devanagari character. 1/ J. l6*. Singhasana. The throne of Raja Vicramaditya ; a series of instructive tales, supposed to have been related by 32 images which ornamented it. Devanagari character. It has been translated into Persian. Ly J. 17. Catha Saritsagara. A collection of tales by Somadeva. Devenagari character. I/J. 18. Suca Saptati. The 70 tales of a parrot. Devanagari character. S. W. J. The Persians seem to have borrowed their Tuti-nama from this work. 19. Rasamanjari. The analysis of love, a poem, by Bhanudatta Misra. Devanagari character. LyJ. 20. Santisataca. A poem, in the Bengal character. 1/ J. 21. Arjuna Gita. A dialogue, something in the manner of the Bhagavat Gita. Devanagari cha- racter. 1/ J. 22. Hitopadesa. Part of the fables translated by C. W. Written in the Bengal character. 1/ J. 23. Brahma Nirupana. On the nature of Brahma. Devanagari character. Imperfect. & J. 24. Meghaduta. A poem. Bengal character. Ly J. 25. Tantra Sara. On religious ceremonies, by Crisbnananda Battacharya. Bengal character. S. W. J, 26. Sahasra Nama. The 1000 names of Vishnu. Devanagari character. S.W.J. 27. Ciratarjuniya. A poem, in the Bengal character. 17 J. 28. Siddhanta Siromani. A treatise on geography and astronomy, by Bhascaracharya. Devanagari character. S. W. J. 29. Sangita Narayana. A treatise on music and dancing. Devanagari character. S. W. J. 30. Vrihadaranyaca. Part of the Yajur Veda, with a gloss, by Sancara. Devanagari character. 1/ J. 31. Niructi, or Nairucta. A gloss on the Veda. Devanagari character. 1/ J. 32. Aitareya. A discourse on part of the Veda. Devanagari character. U J. 33. Chandasi. From the Sama Veda. Devanagari character. 1/ J. 34. Magna Tica. A comment on some other work. Devanagari character. 1/ J. 35. Rajaballabha. De materia Indorem medici ; by Narayanadasa. Bengal character. Jj J. 36. Hatha Pradipaca. Instructions for the performance of the religious discipline called Yoga • by Swatmarama. Bengal character. U J. 37. a. Manava Dharma Sastra. The institutes of Manu, translated into English by S. W. J. under the title of ". Institutes of Hindu Law, or the Ordinances of Menu." Devanagari character. Incor- rect. U J. 37. b. Ditto. Duplicate in the Devanagari character. Very incorrect. U J. 38. Mugdha-bodha-tica. A commentary on the Mugdha-bodha, which is a Sanscrita grammar peculiar to the province of Bengal, by Durga Dasa. Bengal character. Four vols. U J, 39. Saraswati Vyacarana. The Sanscrita grammar called Saraswati. (That part only which treats of the verb.) Devanagari character. 1/ J. 40. Saravali. A grammar of the Sanscrita language. Incomplete. Bengal character. S. W J 41. Siddhanta Caumudi. A grammar of the Sanscrita language, by Panini, Catyayana, and Patan- jali j with a duplicate of the first part, as far as compounds. Devanagari character. I/. J. 42. a. Amara Cosa. A vocabulary of the Sanscrita language, with a grammatical comment. Not perfect. Devanagari character. I/. J. 430 PHILOSOPHICAL TRANSACTIONS. [ANNO 1798. 42. b. Ditto. The botanical chapter only, with a comment. Devanagari character. U. J. 42. c. ditto. The whole complete. Bengal character. S. W. J. 43. Medini Cosa. A dictionary of the Sanscrita language. Devanagari character. I/. J. 44. Viswapracasa Cosa. A dictionary of the Sanscrita language ; by Maheswara. Devanagari character. I/. J. 45. Sabda Sandarbha Sindu. A dictionary of the Sanscrita language ; by Casinatha Sarman. It appears from the introduction, that it was compiled expressly for the use of S. W. J. The learned author is, at present, head professor in the newly-established college at Varanasi. Devanagari character. Two vols, folio. U. J. - 4fJ. Venisanhara. A drama, Sanscrita and Pracrita, in the Bengal character. U. J. 47. Maha Nataca. A drama, Sanscrita and Pracrita, in the Bengal character. Ly. J. 48. Sacuntala. A drama, Sanscrita and Pracrita, in the Bengal character. This is the beautiful play which was translated into English by S. W. J. but not the copy he used for that purpose. I/. J. 49. Malati and Madhava. A drama, Sanscrita and Pracrita, in the Bengal character. U. J. 50. Hasyarnava. A farce, Sanscrita and Pracrita, in the Bengal character. I/. J. 51. Cautuca Sarvaswam. A farce, Sanscrita and Pracrita, in the Bengal character. I/. J. 52. Chandrabhisheca. A drama, Sanscrita and Pracrita. Bengal character. Ly. J. 53. Ratnavali. A drama, Sanscrita and Pracrita. Bengal character. I/. J. 54. Vicramorvasi. A drama, Sanscrita and Pracrita. Bengal character. I/. J. 55. Manavieagninvtra. A drama, Sanscrita and Pracrita. Bengal character. Ly. J. 56. A catalogue of Sanscrita books, on various subjects. Devanagari character. IS. J. n. b. Those articles in the above catalogue, marked S. W. J., were presented by Sir William Jones; and those marked I/. J. by Lady Jones. A catalogue of the Persian and Arabic mss., presented by them, will be given in a future volume. END OF THE EIGHTY-EIGHTH VOLUME OF THE ORIGINAL. 7. The Croonian Lecture. Being Experiments and Observations on the Structure of Nerves. By Ev. Home, Esq., F. R. S. An. 1799, Pol. LXXXIX. p. l. Having had the honour of laying before the r. s. several lectures on the actions of different parts of the organ of vision, the prosecution of the same inquiry has led to some observations on the internal structure of the optic nerve, which will be explained in the present lecture. On the first view, the structure of nerves may appear an improper subject; but, when their offices and connection with muscles are maturely considered, any knowledge respecting them will be allowed an important acquisition towards the investigation of muscular motion. In bringing forward an account of newly-acquired facts, the most natural, and therefore the most satisfactory method is, to begin with the circumstances, which led to their detection. This at present becomes the more proper, as the experiments which brought the subject of nervous structure under consideration, were made on the eye, and were in some measure connected with the observations contained in the former lectures: they were instituted with a view to ascertain the cause of the luminous appearance frequently observed in the cat's eye. The illumination so conspicuous in the eye of the cat, and of many other ani- mals, when seen in an obscure light, has attracted the attention of every common VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 431 observer. Philosophers also have paid particular attention to it, and have endeavoured to investigate the cause. On this subject there have been 2 opinions: one, that the illumination arises from the external light collected in the eye, and reflected; the other, that there is a quantity of light generated in the organ itself. Professor Bohn, at Leipsick, made experiments which proved, that when the external light is wholly excluded, none can be seen in the cat's eye. These experiments were favourable to the first opinion ; but the brightness of the illumination is so great, that it appeared to exceed any effect which could be produced through the medium of the retina; so that some other source of light was thought necessary to account for the phenomenon: this circumstance gave support to the 2d opinion. To determine which of the 2 opinions was just, several experiments were insti- tuted, under the direction of Mr. Ramsden, who also assisted in making them. The truth of Professor Bonn's experiments was readily ascertained; it therefore only became necessary to inquire, whether the external light was of itself capable of producing so great a degree of illumination as that seen in the cat's eye. This was attended with difficulty; for, when the apartment, in which the experiments were made, was so much darkened that nothing but the illumination from the eye was visible, the animal, by change of posture, or some other means, almost im- mediately deprived the observers of all light from that source. This was found to be the case, whether the cat, the tiger, or the hyena, was the subject of the experiment. On the other hand, when the light in the room was sufficient for the animal itself to be seen, the illumination in the eye was more obscure, and ap- peared to arise from the external surface of the iris. As the difficulties which occurred in making observations on the illuminated state of the eye in the living animal were so great, an attempt was made to re- peat, as nearly as possible, the experiments after death. In doing so it was found, that a strong light thrown on the cornea illuminated the iris, as it had done in the living eye; but when the cornea was removed, this illumination disappeared. The iris was then dissected off, and the lucid tapetum completely exposed to view; the reflexion from which was extremely bright; the retina proving no obstruction to the rays of light, but appearing equally transparent with the vitreous humour and crystalline lens. From these experiments it appeared evident that no light is generated in the eye; the illumination being wholly produced by the concave bright-coloured sur- face of the tapetum, collecting the rays of the external light, concentrated by the cornea and crystalline lens, and reflecting them through the pupil. When the iris is completely open, the degree of brilliancy is the greatest; but, when the iris is partly contracted, which it always is when the external light is increased, then the illumination is more obscure, and appears to come from the iris; a part of the light reflected from the tapetum being thrown back, by the concave surface of the. cornea, on the anterior surface of the iris, giving it a bright shining appearance. The influence which the will of the animal has over this luminous appearance 432 PHILOSOPHICAL TRANSACTIONS. [ANNO 1799. seems altogether to depend on the contraction and relaxation of the iris. When the animal is alarmed or first disturbed, it naturally dilates the pupil, and the eye glares; when it is appeased or composed, the pupil contracts, and the light in the eye is no longer seen. The most material information that has been gained in this investigation, is the transparent state of the retina in the eye during life; the opaque membranous appearance which it puts on in the dead body not being natural to it, but a change which takes place in consequence of death. This fact is almost all that is necessary to explain the luminous appearance in the eyes of cats. That neither Baron Haller nor Fontana had an adequate idea of the transpa- rency of the retina, will appear from the following expressions respecting it, taken from their works : Haller describes it in the following words : "Membranam crassam quidem, sed mollisimam, pellucidam utique, quando recens oculus inspicitur, ut per earn sub aquis choroideam videas; tamen ex flavo subcineream."* So that, though he calls it transparent, he says it is of a yellowish ash-colour. Fontana's expressions are, *' Cette insensibilite de la retine, a la lumiere, en tant que lumiere, derive- telle de ce que les nerfs sont encore trop gros, et ne sont pas bien decouverts des tissus cellulaires ? ou de ce que la pulpe de la retine est trop amoncelee, et empeche les rayons de lumiere d'arriver jusqu'a ces memes nerfs V'-\" In considering the use of the lucid tapetum, it was an idea of the late Mr. Hunter's, that the retina received a double stroke from the rays of light which entered the eye; one in passing to the tapetum, the other in returning from it. This very ingenious opinion had some difficulties opposed to it, while the retina was supposed capable of obstructing the rays of light even in the smallest degree, as they could not be equably transmitted, so as to affect every part of the mem- brane alike. But the retina being ascertained to be absolutely transparent, these objections are entirely removed, and there can be no doubt that the rays of light, in those eyes which have a lucid tapetum, must remain on the retina as long again as in the eyes of other animals; since the time required to strike on the tapetum, and return, must be twice as much as is necessary for passing through the retina, to reach the nigrum pigmentum, where they are lost. This may appear to be a consideration of little consequence, as the velocity of light is so great, and the continuance of impression necessary for distinct vision is that produced by a suc- cessive flow of similar rays of light from the object; it may however be all that is necessary for the purpose. The retina being found perfectly transparent, when the eye is examined in a recent state, led to the eye that the internal structure of the optic nerve, when examined in the same state, might also be transparent. To ascertain this point, the following experiment was made: The posterior -£- of a cat's eye, while in a very recent state, was immersed in a basin of water, and examined. The tapetum appeared very bright, the retina not having acquired sufficient opacity to become * Elementa Pbysiologiae, torn. 5, p. 385.-Orig. + Sur le Venin de la Vipere, 1781, vol. 2, p.S19.-Orig. TOL. LXXX1X.] PHILOSOPHICAL TRANSACTIONS. 433 visible: the entrance of the optic nerve was a very white spot, which seemed to be opaque; but, when small pieces of coloured paper were alternately placed between the outside of the eye, and the bottom of the basin, their colour was distinctly seen in the cavity of the eye, through the substance of the optic nerve ; so that, at this part, the internal structure of the nerve has a degree of transparency. This appeared to be a newly-discovered fact; and, to ascertain whether it was really so, the works of several physiological writers were consulted, but nothing was found which gave an idea that their authors had the smallest knowledge of it. This semi-transparent state of the internal parts of the optic nerve, while recent, led naturally to the examination of its substance, by means of magnifying glasses; and notwithstanding the failure of so many men of superior abilities, in this intri- cate inquiry, it held out the hope of meeting with some success. The principal theories which have been formed respecting the structure of nerves, which have been taken notice of by Fontana, as they all differ from the observa- tions which will be stated in the present paper, it may not be improper to mention the heads of each of them, so as to bring into one point of view, all the know- ledge that has been acquired on the subject. Torre found the medullary substance of the brain, spinal marrow, and nerves, to be a mass of transparent globules, swimming in a transparent fluid. When the parts were magnified 1000 times, the globules appeared largest in the brain, and smaller in the spinal marrow; they had no regular order: but in the nerves the globules were placed in lines, so as to give the appearance of fibres. In examining the optic nerve, the parts were mag- nified 120 times. Prochaska considered the nerves to be composed of globules, united by a transparent elastic cellular membrane, and disposed in straight lines, resembling fibres. Fontana found the primitive structure of nerves to consist of transparent cylinders, which, when united, formed the nerve: the manner of their being disposed is not mentioned. The objects were magnified 700 times, to show this appearance. Dr. Monro considered the nerves as made up of spiral fibres; but afterwards found that what he had described was entirely an optical deception. In his last work, he says, " The optic nerves have, in their whole course, less appearance of a fibrous structure than perhaps any other pair of nerves in the human body." Other authors may have written on this subject, and may have made observations on the structure of nerves, but want of leisure must be an excuse for my not having come to a knowledge of them. It is scarcely necessary to mention, that parts of an animal body are not fitted for being examined by glasses of a great magnifying power; and wherever they are shown 100 times larger than the natural size, no dependence can be placed on their appearance. In making the following microscopical experiments on the internal structure of the optic nerve, great care was taken to avoid the errors of former inquirers. The microscope used was a single one; the focal length of the lens was about tVo°^ an inch, so that the object was magnified about 23 times; and, that the results of the experiments might be as free from optical deceptions VOL. XVIII. 3 K 434 PHILOSOPHICAL TRANSACTIONS. [ANNO 17 9Q. as the present state of our knowledge in this branch of science will admit, no ap- pearance is described which Mr. Ramsden was not satisfied of having distinctly seen. The experiments performed with the single microscope were repeated with a double one, made by Mr. Ramsden, which magnified the object about 40 times; but in the double microscope the appearances were indistinct, the reflexion from the different glasses having thrown a confused glare on the moist surface of the nerve. This circumstance led Mr. Ramsden to object to the use of compound microscopes, and to consider them as unfit for viewing objects of this kind. For the following reasons, the optic nerve of the horse was selected, as the most proper for the experiment. It is of a large size, and several inches in length. It is readily procured in a recent state; as there are places in London where horses are allowed to be killed, and regular days in the week are fixed for that purpose. That the examination of the nerve might be made as soon as possible after the animal's death, permission was procured from the man who superintends the killing of horses, to allow Mr. Clift to make the necessary experiments on the spot, the moment the horses were killed. Mr. Clift is the person entrusted with the care of keeping in order the late Mr. Hunter's collection in comparative anatomy, and is well qualified, from his anatomical knowledge, and a familiarity in looking at organized parts through magnifying glasses, for an examination of this kind. These experiments were afterwards repeated by Mr. Ramsden and myself. From this mode of conducting them, the chances of error were few ; since the person who first observed the appearances had no previous opinions on the subject ; and Mr. Ramsden was better able than any other person, to correct such optical errors as might deceive Mr. Clift or myself. The first experiments were made on transverse sections of the nerve. One, near its termination in the eye, was placed on glass, and exhibited in the micros- cope the following appearances : it was evidently composed of 1 parts, 1 opaque, the other transparent. The opaque portions were nearly circular in their shape, about 600 in number, and touched each other ; the interstices between them were transparent. When the opaque parts were attentively examined in a favourable light, and the nerve was in a recent state, they were found to be made up of a great number of smaller portions, each of which appeared to be also opaque. To see this subdivision of parts required some attention, and in many sections it could not be perceived. The cause of the difficulty seemed to be, the softness and tena- city of the substance divided, which therefore spread itself over the surface, giving it a uniform appearance : but towards the circumference of the nerve, where the parts were cut obliquely, and some of them tome, the subdivision was very distinct. It was first observed by Mr. Clift, in several different sections; and was afterwards seen very distinctly, both by Mr. Ramsden and myself, in a nerve examined about 1 hours after death. Having repeated these experiments 6 or 7 times, on different days, so as to ascertain the accuracy of the results, the next object was, to determine whether VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 435 the nerve had the same structure in its whole coui se. For this purpose, transverse sections were examined in different parts of the nerve, near the brain towards the middle, and nearer the eye: of these experiments the following are the results. In all the sections, the nerve appeared to be made up of the same substances ; but the size and number of the opaque parts differed very much. They have been stated, near the eye, to be 600; about the middle of the nerve, they were 150; and, near the brain, between the origin and union of the 2 nerves, they were only about 40. As they became larger, they were less regular in their shape, and had less of a circular form ; nor were they uniform, some appearing very large, with 1 or 2 smaller placed between them. After having succeeded in this examination of the nerve transversely, an at- tempt was made to investigate its structure in a longitudinal direction. To do this, a portion of the nervous pulp had its coat, formed by the dura mater, along with a thin vascular membrane which lines it, carefully removed for about an inch in length ; the external surface of the pulp was then examined with a magnifying glass; the structure was evidently fasciculated, but the fasciculi did not run parallel to each other; they seemed to unite together and separate again, in such a manner that any one of them could not be traced for half an inch in length, without being lost in the neighbouring part. When thin sections were examined in the field of the microscope, they put on the same appearance: this was equally the case, whe- ther the part examined was near the centre or circumference of the nerve. The fasciculi were largest in that part of the nerve near the brain, and smallest towards the eye. Great pains were taken to ascertain whether the fasciculi were made up of continued fibres, or of small parts unconnected, which, from their position, gave that appearance; but every observation that was made was in proof of their being continued fibres. From these experiments, the internal structure of the optic nerve appears to be made up in the following manner: At its origin from the brain, it consists of 30 or 40 fasciculi or bundles of extremely small opaque pulpy fibres, the interstices between which are filled with a transparent jelly. As the nerve goes farther from the brain, the fasciculi form smaller ones of different sizes. This is not done by a regular subdivision, but by a few fibres going off laterally from several large fasciculi, and being united, forming a smaller one: some of the fasciculi so formed, which are very small, unite again into one. In this way, the fasciculi gradually diminish in size, and increase in number, till they terminate in the retina. Near the eye, where the fasciculi are most numerous, the substance of the nerve has a considerable degree of transparency, from the number of trans- parent interstices between them; but this is less the case nearer the brain, where the interstices are fewer. In the optic nerve of the cat, the structure is the same as in the horse; but, from the smallness of the parts, less fitted for investigation. Near the eye, its internal substance is more transparent than the corresponding part in the horse. 3k2 436 PHILOSOPHICAL TRANSACTIONS. [ANNO \7QQ. To see how far this structure was peculiar to the optic nerve, similar experiments were made on the internal substance of the 5th and 7th pair of nerves, near their origin at the brain, and the structure was found to be the same. In these last mentioned nerves, the interstices between the fasciculi were smaller than in the optic nerve, rendering their transverse sections less transparent; from which it is natural to suppose, that the internal parts of the optic nerve are not so compact as in other nerves, and therefore it is better fitted for examination. These experiments show, that the nerves do not consist of tubes conveying a fluid, but of fibres of a peculiar kind, different from every thing else in the body, with which we are acquainted. The course of these fibres is very curious; they appear to be constantly passing from one fasciculus to another, so as to connect all the different fasciculi together by a mixture of fibres. This is different from the course of blood-vessels, lymphatics, or muscular fibres: the only thing similar to it, is in the formation of nervous plexuses; which leads to the idea of its answering an essential purpose, respecting the functions of the nerves. J I. Observations on an Unusual Horizontal Refraction of the Air ; with Remarks on the Variations to which the Lower Parts of the Atmosphere are sometimes Sub- ject. By the Rev. S. Vince, A.M., F.R.S. Being the Bakerian Lecture, p. 13. The uncertainty of the refraction of the air near the horizon has long been known to astronomers, the mean refraction varying by quantities which cannot be accounted for from the variations of the barometer and thermometer; on which ac- count, altitudes of the heavenly bodies, which are not more than 5° or 6°, ought never to be made use of when any consequences are to be deduced from them. The cause of this uncertainty is probably the great quantities of gross vapours, and exhalations of various kinds, which are suspended in the air near the earth's surface, and the variations to which they are subject; causes of which we have no instruments to measure the effects they produce, in refracting the rays of light, In general, the course of a ray passing through the atmosphere, is that of a curve which is concave towards the earth, the effect of which is to give an apparent ele- vation to the object; and thus the heavenly bodies appear above the horizon, when they are actually below it; but it will not alter the position of their parts, in respect to the horizon, that is, the image of the highest part of the object will be upper- most, and the image of the lowest part will be undermost. The figures however of the sun and moon, when near the horizon, will suffer a change, in consequence of the refraction of the under limb being greater than that of the upper; from which they assume an elliptical form, the minor axis of which is perpendicular to the horizon, and the major axis parallel to it. But a perpendicular object, situated on the surface of the earth, will not have its length altered by refraction, the refraction of the bottom being the same as that of the top. These are the effects which are produced on bodies at or near the horizon, in the common state of the atmosphere, by what I shall call the usual refraction. VOL. LXXX1X.] PHILOSOPHICAL TRANSACTIONS. 437 But, besides the usual refraction which affects the rays of light, the atmosphere over the sea is sometimes found to be in a state which refracts the rays in such a manner as to produce other images of the object, which we will call an effect from an unusual refraction. In the Phil. Trans, for 1797, Mr. Huddart has described some effects of this kind, which he has accounted for by supposing that, from the evaporation of the water, the refractive power of the air is not greatest at the sur- face of the sea, but at some distance above it; and this will solve, in a very satis- factory manner, all the phenomena which he has observed. But effects very dif- ferent from those which have been described by Mr. Huddart are sometimes found to take place. These I had an opportunity of observing at Ramsgate last summer, on August the first, from about half an hour after 4 o'clock in the afternoon till between 7 and 8. The day had been extremely hot, and the evening was very sultry; the sky was clear, with a few flying clouds. I shall describe the pheno- mena as I observed them with a terrestrial telescope, which magnified between 30 and 40 times ; they were visible however to the naked eye. The height of the eye above the surface of the water, at which most of the observations were made, was about 25 feet; some of them however were made at about 80 feet from the surface; and it did not appear that any of the phenomena were altered by varying the height of the eye, the general effect remaining the same. The first unusual appearance observed, was that which is represented in pi. 8, fig. ]. Directing my telescope at random, to examine any objects which might happen to be in view, I saw the top of the masts of a ship a, above the horizon xy, of the sea, as shown in the figure; at the same time also, I discovered in the field of view, 2 complete images, b, c, of the ship in the air, vertical to the ship itself, b being inverted, and c erect, having their hulls joined. The phenomenon was so strange, that I requested a person present to look into the telescope, and examine what was to be seen in it, who immediately described the 2 images, as observed by myself; indeed they were so perfect, that it was impossible we could differ in our description. On this I immediately took a drawing of the relative magnitudes and distances of the ship and its images, which at that time were as represented in the figure, as near as it was possible for the eye to judge; and it was very easy to estimate them to a very considerable degree of accuracy. As the ship was receding from the shore, less and less of its masts became visible; and, conti- nuing my observations, in order to discover whether any, or what variations might take place, I found that as the ship descended, the images b, c, ascended; but as the ship did not sink below the horizon, I had not an opportunity of observing at what time, and in what order, the images would have vanished, if the ship had so disappeared. Being desirous of seeing whether the same effect was produced on the other ships which were visible, I directed my telescope to another ship a, fig. 2, whose hull was just in the horizon xy ; when I observed a complete inverted image b, the main- mast of which just touched that of the ship itself. In this case, there was no 2d 438 PHILOSOPHICAL TRANSACTIONS. [ANNO 179Q. image as before. The ship a moving on the horizon, b continued to move with it, without any variation in its appearance. The next ship I directed my telescope to, was so far on the other side of the horizon xy, as just to prevent its hull from being seen, as is represented by a, fig. 3. And here I observed only an inverted image of part of the ship; the image y of the topsail, with the mast joining that of the ship, the image x of the top a of the other mast, and the image z of the end c of the bowsprit, only appearing at that time. These images would suddenly appear and disappear very quickly after each other; first appearing below, and running up very rapidly, showing more and less of the masts at different times, as they broke out; resembling, in the swiftness of their breaking out, the shooting out of a beam of the aurora borealis. As the ship was descending on the other side of the horizon, I continued my observations on it, in order to discover what changes might take place; when I found, that as it con- tinued to descend, more of the image gradually appeared, till at last the image of the whole ship was completed, with their main-masts touching each other; and, on the ship descending lower, the image and the ship separated; but I observed no 2d image, as in the first case; a 2d image however might probably have appeared, if the ship had continued to descend. On moving my telescope along the horizon, in order to examine any other ships which might be in sight, I observed, just at the horizon xy, in fig. 4, the top a of the mast of a ship; and here an effect was observed which had not been before dis- covered; for there was an inverted image b, vertical to a, an erect image c, both of them very perfect and well defined, and an image vw of the sea between them, the water appearing very distinctly. As the ship was coming up towards the horizon, I continued to observe it, in order to discover the variations which might follow, and found, that as the ship approached the horizon, the image c gradually disap- peared, and at last it vanished; after that, the image vw of the sea disappeared; and during this time the image b descended; but the ship did not rise so near to the horizon as to bring the main-masts together. Had I directed my telescope to the same point of the horizon a little sooner, I should have seen the 2 images before the ship itself was visible. In fact, the images were visible when the whole ship was actually below the horizon; for, from the very small part of the mast which was at first visible, that part must then have been below the horizon, and appeared above it by the usual refraction; the altitude of a, above the horizon, having then been much less than the increase of altitude which arises from the common hori- zontal refraction. The discovery of ships in this manner might, in some cases, be of great importance; and on such occasions it might be worth while to appoint proper persons to make observations for that purpose. The cliffs at Calais being very visible, I directed my telescope towards them, in order to examine whether there was any thing unusual in their appearance; when I observed an image of the cliffs, above the cliffs themselves, together with an image of the sea separating them, as is represented in fig. 5 ; in which, xy repre- VOL. LXXXIX.J PHILOSOPHICAL TRANSACTIONS. 439 sents the horizon of the sea, ab the cliffs, ab their image, and vw the image of the sea between them: the depth of ab was much less than that of ab. It is pro- bable however, that vw might not be the image of the sea immediately adjoining to the cliffs, but a partial elevation of the sea at some distance from them ; and that the image vw might intercept some part of the image ab, which would other- wise have been visible; we must not therefore conclude that the image ab, so far as it appeared, was less than the corresponding part of the object. From the memo- randums which I made at the time of observation, I do not find that I examined the appearance of the cliff ab, and its image ab; which, had there at that time been any striking marks in them, would have determined whether the object and its image were of the same magnitude. The image ab was however erect; the boun- daries on the top of ab and ab agreeing together. Having examined this for some time, and taken a drawing of the appearance, during which I could discover no variation, I directed my telescope to other objects; and on turning it again to the same cliffs, after the space of about 6 or 7 minutes, the images ab and vw were vanished ; but examining them again soon after, the images were again visible, and in every respect the same as they appeared before. A short time after they disap- peared, and did not appear any more. Soon after the above appearances, I observed a ship c, with the hull below the horizon xy, passing by the same cliffs ab ; an inverted image d of which appeared against the cliffs, as represented in fig. 6. The ship was in motion, and remained at the same distance on the other side of the horizon : I continued my observations on it till it had passed the cliffs for a considerable distance, but there was no change of appearance. The cliffs were illuminated by the sun, and appeared very distinctly; but there was no image above, as in the last case. Continuing to ob- serve the same cliffs ab, fig. 7, I soon after discovered 2 partial elevations m, n, of the sea, by the unusual refraction ; they changed their figures a little, and disap- peared in the place where they first appeared, and were equally distinct in every part. About this time, I observed a very thick fog coming on the horizon from the other side, rolling on it with a prodigious velocity; curling as it went along, like volumes of smoke sometimes out of a chimney. This appeared several times. I conclude therefore, that there was a considerable fog on the other side of the ho- rizon. The last phenomenon observed was that represented in fig. 8; where xy represents the horizon, ab 2 partial elevations of the sea, meeting at c, and conti- nued to d; e, another partial elevation of the sea, of which kind I observed several, some of which moved parallel to the horizon, with a very great velocity. I con- jecture therefore, that these appearances were, in part at least, caused by the fog on the other side of the horizon. For though I did not at the same time see the motion of these images and that of the fog, yet from memory I judged the motions to be equal: and they were also in the same direction. A fog which, by producing an unusual refraction, might form these images, would, by its motion, produce a corresponding motion of the images. 440 PHILOSOPHICAL TRANSACTIONS. [ANNO 17QQ. I have here described all the different phenomena which I observed from the un- usual refraction, of most of which I saw a great many instances. Every ship which I observed on the other side of the horizon of the sea, exhibited phenomena of the kind here described, but not in the same degree. Of 2 ships which in dif- ferent parts, were equally sunk below the horizon, the inverted image of one would but just begin to appear, while that of the other would represent nearly the whole of the ship. But this 1 observed in general, that as the ship gradually descended below the horizon, more of the image gradually appeared, and it ascended ; and the contrary when the ships were ascending. On the horizon, in different parts, one ship would have a complete inverted image; another would have only a partial image; and a 3d would have no image at all. The images were in general ex- tremely well defined ; and frequently appeared as clear and sharp as the ships them- selves, and of the same magnitude. Of the ships on this side of the horizon, no phenomena of this kind appeared. There was no fog on our coast; and the ships in the Downs, and the South Foreland, exhibited no uncommon appearances. The usual refraction at the same time was uncommonly great ; for the tide was high, and at the very edge of the water I could see the cliffs at Calais a very consi- derable height above the horizon ; whereas they are frequently not to be seen in clear weather from the high lands about the place. The French coast also appeared both ways, to a much greater distance than I ever observed it at any other time; particularly towards the east, on which part also the unusual refraction was the strongest. During the remainder of my stay at Ramsgate, which was about 5 weeks, I con- tinued daily to examine all the ships in sight; but I discovered no phenomena similar to those above described. The phenomenon of the ship observed by Mr. Huddart, differed altogether from those above described, as the inverted image which he observed was below the ship itself. An appearance of this kind I ob- served on August the 17th, about half an hour after 3 in the afternoon, of which fig. 9 is a representation. The real ship is represented by a, and the image by b; er, mv, the hulls; st the flag, and wx its image, just touching it, with the sea xy below. Between the 2 hulls, some faint dark spots and lines appeared, but I could not discover what they were the representatives of. The vessel, at the time of this appearance, was not quite come up to the horizon ; and as it approached it, the image gradually diminished, and totally disappeared when the ship arrived at the horizon. It remains now, that we inquire into the causes which might produce the very extraordinary effects above related. From the phenomena, we are immediately led to the nature of the path of the rays of light to produce them ; and we may con- ceive, that the air may possibly be in such a state as will account for the unusual track which they must have described, For, let bz, fig. 10, be the surface of the sea ; ab an object ; e the place of the eye ; arE, bsE, the progress of 2 rays, by the usual refraction, from the extreme parts of the object to the eye ; to these curves VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 441 draw the tangents Ea', ed', and a' b' will be the image of the object, as usually formed. Now if we take the case represented in fig. 4, let a" b" represent the in- verted image, and a'" b'" the erect image ; join a'7E, the a"'E, and Me, d'"e, and these lines must respectively be the directions of the rays entering the eye from a and b, in order to produce the images a" h" and a"" b'" ; hence these lines must be tangents at e, to the curves which are described by the rays of light ; let therefore anE, amE, bvE, bwE, be the curves described. We have therefore to assign a cause which may bring rays passing above the rays arE, bsE, to the eye at e. Now if there were no variation of the refractive power of the air, a ray of light passing through it would describe a straight line ; therefore the curvature of a ray of light passing through the atmosphere, depends on the variation of the refractive power of the air. If therefore we suppose the air lying above arE, to vary quicker in its refractive power than the air through which arE passes, the curvature of a ray proceeding above that of arE, will be greater than the curvature of ars ; and on this principle we may conceive that a ray may describe the curve anE : and, in like manner, if a quicker variation of refractive power should take place above the curve anE, than in that curve, a 3d ray may describe the curve amE. The same may be said for the rays bvE, bwE, diverging from b. The alterations of the re- fractive power may arise, partly from the variations of its density, and partly from the variations of its moisture ; and the passage of the rays through the boundary of the fog may there suffer a very considerable refraction ; for, from the motion of the fog, and that of the images above-mentioned, I have no doubt that the fog was a very considerable agent in producing the phenomena. When all the causes co-operate, I can easily conceive that they may produce the effects which I have described. If the cause should not operate in the tract of air through which the curves anE, bvE pass, but should operate in the tract through which amE, bwE pass, an erect image would be visible, but there would be no inverted image ; and should it operate in the latter case, but not in the former, there would be Only an inverted image. As the phenomena are very curious, and extraordinary in their nature, and have not, that I know of, been before observed, I have thought proper to lay a descrip- tion of them, with all the attending circumstances, before the r. s. They appear to be of considerable importance ; as they lead us to a knowledge of those changes to which the lower parts of the atmosphere are sometimes subject. If, when these phenomena appear, a vessel, furnished with a barometer, thermometer, and hygro- meter, below, and also at the top of the mast, were sent out to pass below the horizon and return again, and an observer at land, having like instruments, were to note, at certain intervals, the situation and figure of the images, it might throw further light on this subject, and lead to useful discoveries respecting the state of the atmosphere, from a conjunction of the causes which affect these instruments. vol. xvm. 3 L 442 PHILOSOPHICAL TRANSACTIONS. [anno 1799. ///. Abstract of a Register of the Barometer, Thermometer, and Rain, at Lyndon, in Rutland, 1/97. With some Remarks on the Recovery of injured Trees. By Thes. Barker, Esq. p. 24. Barometei Thermometer. j Rain. In the House. Abroad. Highest. Lowest. Mean. ^Hig. Low Mean Hig.Low Mean 1 luchei. Inches. Indies. e „ O O „ „ 1 Inch. Jan. Mom. Aftern. 29.99 29.01 29. ^8 46 48 33 36 39 40 48 51 26 29 37 39 1.319 Feb. Morn. Aftern. 30.07 28.84 50 47 48 37 38$ 42 43$ 46$ 52\ 25 32 34 42$ 0.076 Mar. Morn. Aftern. 29.90 29.03 47 46 47 38 39 41$ 43 46 53 29$ 36$ 35$ 44$ 0.908 Apr. Morn. Aftern. 29.70 28.63 31 51$ 52$ 43$ 46 47 52 59 36 37 42$ 49 2.882 May Morn. Aftern. 29.86 28.44 38 67 69 44 44$ 53 54$ 64 76 38 41$ 50$ 59$ 2.528 June Morn. Aftern. 29-85 28.93 41 60 62$ 52 53% 57 58 63 76 39$ 43$ 52$ 63 4.221 July Morn. Aftern. 29.80 29.05 49 70$ 57 59 63 65$ 66 83 54 60 61 72$ 3.075 Aug. Morn. Aftern. 29.72 29.05 35 64 65h 58 59 60$ 62 64 76 49 62 58 68 2.415 Sept. Morn. Aftern. 29.67 28.67 28 62 64 51$ 54 56 57 58 70$ 43 51 50 60 4.792 Oct. Morn. Aftern. 29.83 28.57 37 55$ 571 41$ 42$ 49$ 50 55 63 31$ 42$ 44 52 1.143 Nov. Morn. Aftern. 29-98 28.50 43 49 491 34 34$ 43$ 44 51$ 53 24$ 30 38$ 44 1.620 Dec. Morn. Aftern. 29.93 28.60 27 49$ 49$ 36 36\ 42 42$ 53 53 29 32 3s$ 42 2.875 Who] e year. 29.40 50 49 27.854 Chi the recovery of injured trees. — About the year 17S8 or 1789, a Lucombe oak was planted, the top of which might be about 6 feet high, but was broken off in coming down. In spring, the tree put out at the highest 2 buds, but much better at some lower ones. In 1791, the highest 2 buds again put out, yet, as be- fore, very indifferently ; however, a lower bud, about 5 feet high, put out a strong shoot, about 1 5 inches long ; but, as side branches are apt to do, it did not grow upright, but slanting. In winter I fixed that strong shoot upright, by tying it to another shoot, which came out of the opposite side of the tree; and in 1792 it made a very strong, straight, and upright shoot, 3 feet 9 inches long, and as thick as a moderate finger, and has continued thriving ever since. The tree is now about 18 feet high, and 11 inches in girth at the bottom ; it has been pretty well cleared of boughs about half way up, and may perhaps, by degrees, be cleared se- veral feet higher. In the winter of 1789, an ash tree was cut down, which, falling against a young oak, as thick as my leg, beat it down. I had the oak cut close to the ground, and VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 443 in 1790 it put out a number of shoots, which grew that year, and 1791. In 1792, I chose out the best shoot, trained it up as straight as I could, and beat down the rest of the shoots to the ground, under the hedge, to weaken them, and encourage the best shoot, which I intend to be the tree. It has since grown strong, is pretty straight, has been pruned, and may I believe by degrees be cleared to a good height, for the leading bud is Strong and upright. It is now (in August, 1 798) about 14^ feet high, and about 64 inches in girth at the bottom. IV. Additions to a Paper, on the Subject of a Child with a Double Head. By Evd. Home, Esq. F. R. S. p. 28. In the year 1 790, I laid before the r. s. an account of a child with a double head, illustrated by drawings, which is honoured with a place in the Phil. Trans., vol. 80, (Abridgt. vol. 16, page 663). Since that time, Mr. Dent, the gentleman who sent over from India the double skull, which was shown at the meeting when the paper was read, has returned to England. Among his drawings there are 2 portraits of the double head, taken by Mr. Devis, an artist of considerable merit, who was on a visit at Mr. Dent's house, in Bengal, when the child was brought there alive, to be shown as a curiosity. These drawings give a more faithful re- presentation of the appearance of the double head, than the engravings annexed to the former paper, and at the same time exhibit a striking likeness of the child's features. Mr. Dent's observations, in addition to those already in the possession of the Society, are the following. The child was a male. Its father was a farmer at Mundul Gaut, in the province of Bardwan, who told Mr. Dent, that it was more than 4 years old at the time of its death *. The mother, who was 30 years of age, had 3 children, all naturally formed ; and her 4th child was the subject of the present paper. Mr. Dent endeavoured to discover whether any imaginary cause had been assigned by the parents, for the unnatural formation of the child ; but the mother declared, that no circumstance whatever, of an uncommon nature, had occurred : she had no fright, met with no accident, and went through the period of her pregnancy exactly in the same way as she had done with her other chil- dren. The body of the child was uncommonly thin, appearing emaciated from want of due nourishment. The neck of the superior head was about 4 inches long; and the upper part of it terminated in a hard, round, gristly tumour, nearly 4 inches in diameter. The front teeth had cut the gums, in the upper and under jaws of both heads. When the child cried, the features of the superior head were not always affected ; and when it smiled, the features of the superior head did not sympathize in that action. In preparing the skull, which unpleasant operation Mr. Dent was obliged, from the prejudices of his servants, to superintend, he found that the dura mater be- longing to each brain, was continued across, at the part where the 2 skulls joined, * In the former account, the child is said to have been about 2 years old at that time. — Orig. 3l 2 444 PHILOSOPHICAL TRANSACTIONS. [aNNO 17QQ. so that each brain was invested, in the usual way, by its own proper coverings ; bat the dura mater which covered the cerebrum of the upper brain, adhered firmly to the dura mater of the lower brain : the 1 brains were therefore separate and distinct, having a complete partition between them, formed by a union of the durae matres. When the contents of the double skull were taken out, and this union of the durae matres more particularly examined, a number of large arteries and veins were seen passing through it, making a free communication between the blood-vessels of the 2 brains. This is a fact of considerable importance, as it ex- plains the mode in which the upper brain received its nourishment. Before these observations were communicated by Mr. Dent, it was natural to suppose that the 1 brains had been united into ] mass ; as it was difficult to imagine in what way the upper brain could be supplied with blood. V. Observations on the Manners, Habits, and Natural History, of the Elephant. By Jno. Corse, Esq. p. 31. Since the remotest ages, the elephant, on account of his size, his sagacity, and his wonderful docility, has attracted the notice, and excjted the admiration, of philosophers and naturalists, both ancient and modern: and few travellers into Asia, or Africa, have omitted giving some account of him. A residence however of more than 10 years, in Tiperah, a province of Bengal, situated at the eastern extremity of the British dominions in Asia, where herds of elephants are taken every season, afforded me frequent opportunities of observing, not only the methods of taking them, but also the habits and manners of this noble animal. From the year 1792 till 1797, the elephant hunters were entirely under my di- rection; so that I had it in my power to institute such experiments as I thought likely to discover any particulars, not formerly known, in the natural history of the elephant. Soon after my arrival at Tiperah, while informing myself of the methods of taking wild elephants, I had occasion to observe, that many errors, relative to the habits and manners of that useful animal, had been stated in the writings of European authors, and countenanced by some of the most approved writers. The elephant has been declared to possess the sentiment of modesty in a high degree; and, by some, his sagacity was supposed to excite feelings for the loss of liberty, so acute, as to cause him to refuse to propagate his species while in slavery, lest he should entail on his progeny a fate similar to his own; while others have asserted, that he lost the power of procreation in the domestic state. So circum- stanced, I was desirous of taking advantage of my situation, and of making such experiments and observations, as might tend to render more perfect the natural history of this useful animal. Early in the year 1789, I gave an account of the methods then used for taking and training wild elephants, to the Asiatic Society in Calcutta, which was published in vol. 3, of their researches; and the following VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 445 experiments and observations, made since that period, on the natural history of the elephant, will not, I hope, prove unworthy the attention of the k. s. The young of the elephant, at its birth, is about 35 inches high; and, as a knowledge of its progressive growth forms the best criterion by which we can judge of the age of this animal, I shall here note down some observations made on this subject, till the elephant has attained its full size; for, after this period, till signs of old age appear, I do not know any marks by which a tolerable guess can be made of the number of its years, unless we could examine the teeth accurately; and even then there would be much uncertainty. Very erroneous notions have been entertained, with respect to the size of elephants, in different parts of India; for which reason, I have collected such facts as were likely to ascertain their general height. The following observations, of the gradual increase of growth, were made on a young elephant of Mr. Stephen Harris, which was accurately measured from time to time, and on a female elephant of my own, till I left Tiperah. Mr. Harris's elephant, at its birth, Oct. l6, 1789, was 35 inches high. In 1 year he grew 11 inches, and was 3 feet 10 inches high. In the 2d year he grows 8 inches. In the 3d, (3. In the 4th, 5. In the 5th, 5. In the 6th, 34-. In the 7th, 2-J-. And was then 6 feet 4 inches high. Except during his 4th and 5th years, this measurement shows a gradual decrease in the proportion of growth for every year; and there was no opportunity of tracing the growth of this elephant further than its 7th year. Another elephant, 6 feet Q inches high, at the time she came into my possession, was supposed to be 14 years old; but as the accuracy of the hunters cannot be de- pended on, it will be proper to take Mr. Harris's elephant, whose age is exactly known, as a standard; and, judging from its annual increase, this will lead us to consider the elephant, at the time I received her, to be only 11 years old; giving a period of 4 years, for the addition of 5 inches. I have made a greater allowance of time, on account of this elephant being a female, and Mr. Harris's a male, which there is much reason to believe grows faster. During the next 5 years, before she was covered, she grew only 6 inches; but, what is extremely curious, while pregnant, she grew, in 21 months, 5 inches; and, in the following 17 months, though again pregnant, she grew only 4- an inch ; at which time, she was sent from Comillah, as I was then preparing to leave India. At this time, she was about 19 years old, and had perhaps attained her full growth. Her young one was then (Nov. 17 96) not 20 months old; yet he was 4 feet 54- inches high, having grown 18 inches since his birth; which is the greatest progressive growth in the elephant that I have known. These observations, when applied to the general growth of elephants, are to be taken with some allowance; since, during the state of the first pregnancy, there is so great an irregularity in the growth of female elephants, as alone occasions con- siderable difficulty, even supposing the progressive growth nearly equal in the species. It is probable, however, that this is not by any means equal: for, as 446 PHILOSOPHICAL TRANSACTIONS. [ANNO 17QQ. elephants vary greatly in size, and as males are generally much taller than females, we must conclude they either grow faster, or are longer in attaining their full growth*. But it may be safely asserted, that elephants, like most quadrupeds, propagate their species before they have acquired their full growth. Many females have been known, when taken while pregnant, to have grown several inches higher before delivery; and, as it has been stated, that the female elephant on which my observations were made, could not exceed l6 years when she received the male, it is probable the wild female elephants are in heat before that period. If from the above data, it may be allowed to form a probable conjecture, elephants attain their full size between ] 8 and 24 years of age. The height of the elephant, I believe, has been generally much exaggerated. In India, the height of females is, in general, from 7 to 8 feet; and that of males, from 8 to 10 feet, measured at the shoulder. I have never heard of more than one elephant, on good authority, that much exceeded 10 feet: this was a male, belonging to Asoph ul Dowlah, the late vizier of Oude. His dimensions, as communicated by Mr. Cherry, then resident at Lucknow, were as follow, measured on the 1 8th of June, 1796: from foot to foot, over the shoulder 22 feet 10^ inches. From the top of the shoulder, perpendicular height 10 feet 6 inches. From the top of the head, when set up, as he ought to march in state 12 feet 2 inches. From the front of the face to the insertion of the tail 15 feet 11 inches. Capt. Sandys, of the Bengal establishment, showed me a list of about 150 elephants, of which he had the management during the late war with Tippoo Sul- taun, in Mysore, and not one of them was 10 feet, and only a few males Q-l. I was very particular in ascertaining the height of the elephants employed at Madras, and with the army under Marquis Cornwallis, where there were both Ceylon and Bengal elephants; and I have been assured, that those of Ceylon were neither higher, nor superior, in any respect, to those of Bengal; and some officers assert, that they were considerably inferior, in point of utility. The Madras elephants have been said to be from 17 to 20 feet high ; but, to show how much the natives of India are inclined to the marvellous, and how liable Europeans themselves are to mistakes, I will relate a circumstance that happened to myself. Having heard, from several gentlemen who had been at Dacca, that the Nabob there had an elephant about 14 feet high, I was desirous to measure him; especially as I had seen him often myself, during the year 1785, and then supposed him to be above 12 feet. After being at Tiperah, and having seen many elephants caught, in the years 1786, 1787, and 1788, and finding all of them much in- ferior in height to what I supposed the Nabob's elephant, I went to Dacca in 1789, determined to see this huge animal measured. At first, I sent for the mahote or driver, to ask some questions concerning this elephant; he assured me he was from * A male elephant, belonging to the Cudwah Rajah till he was above 20 years of age, continued to increase in height, and was supposed not to have attained his full size, when I left Tiperah : he was then about 22 years old. — Orig. VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 447 10 to 12 cubits, that is, from 15 to 18 feet high; but added, he could not, with- out the Nabob's permission, bring me the elephant to be examined. Permission was accordingly asked, and granted: I had him measured exactly, and was rather surprized to find he did not exceed JO feet in height. The Company's standard, for serviceable elephants, is 7 feet and upwards, measured at the shoulder, in the same manner as horses are. At the middle of the back, they are considerably higher; the curve or arch of which, particularly in young elephants, makes a difference of several inches. After an elephant has attained his full growth, it is a sure sign of old age when this curve becomes less; and still more so, when the back is flat, or a little depressed. A partial depression of the spine is however no uncommon occurrence, even in very young elephants; and I am convinced it happens from external injury. I have been surprized to see the violence used, in herds of wild elephants just taken, by the large elephants, both male and female, putting the projecting part of the upper jaw, from which the tusks grow out, on the spine of the young ones, and pressing them to the ground, while they roared from pain. It has been stated, that the sagacity of the elephant is so great, and his memory so retentive, that when once he has received an injury, or been in bondage, and afterwards escapes, it is not possible, by any art, again to entrap him. Great as my partiality is for this noble animal, whose modes of life and general sagacity 1 have had so many opportunities of observing, yet a regard to truth compels me to mention some facts, which contradict that opinion. The following history of an elephant taken by Mr. Leeke*, of Longford Hall, Shropshire, contains many in- teresting particulars on this subject. The elephant was a female, and was taken at first, with a herd of many others, in 1765, by Rajah Kishun Maunick-j-, who, about 6 months after, gave her to Abdoor Rezah, a man of some rank and conse- quence in the district. In 1767, the Rajah sent a force against this Abdoor Rezah, for some refractory conduct, who, in his retreat to the hills, turned her loose into the woods, after having used her above 2 years, as a riding elephant. In Jan. 1770, she was retaken by the Rajah; but, in April, 177 1> she broke loose from her pickets, in a stormy night, and escaped to the hills. On Dec. 25, 1782, she was driven by Mr. Leeke's elephant hunters into a keddahj; and the day following, when Mr. Leeke went to see the herd that had been secured, this elephant was pointed out to him by the hunters, and particularly by a driver who had had charge of her for some time, and well recollected her. They frequently called to her by name; to which she seemed to pay some attention, by immediately looking towards them, when her name, Jugget-Peauree, was repeated; nor did she appear like the * He was then the Resident of Tiperah, and took some pains to ascertain the facts here mentioned. — t The Rajah is the principal Zemindar in the province of Tiperah, paying the usual revenue for his lands in the low country ; but in the hills he is an independent sovereign, has the power of life and death over his subjects, a mint, and other insignia of sovereignty. % The inclosure in which elephants are secured. Vide Asiatic Researches, vol. 3, art. ' ' Method of catching Elephants."— Orig. 448 PHILOSOPHICAL TRANSACTIONS. [ANNO 17QQ. wild elephants, which were constantly running about the keddah in a rage, but seemed perfectly reconciled to her situation. From Dec, 25 to Jan 13, a space of 18 days, she never went near enough the outlet, or roomee, to be secured; from a recollection perhaps of what she had twice before suffered*. Orders however had been given, not to permit her to enter the outlet, had she been so inclined, as Mr. Leeke wished to be present when she was taken out of the keddah. On Jan. 13, 1783, Mr. Leeke went out, when there wene only herself, another female, and 8 young ones, remaining in the in- closure. After the other female had been secured, by means of the koomkees4- sent in for that purpose, the hunters were ordered to call Juggut-Peauree. She im- mediately came to the side of the ditch, within the inclosure; on which, some of the drivers were desired to carry in a plaintain tree, the leaves of which she not only took from their hands, with her trunk, but opened her mouth, for them to put a leaf into it, which they did, stroking and caressing her, and calling to her by name. Mr. Leeke, seeing the animal so tame, would not permit the hunters to attempt tying her; but ordered one of the trained elephants to be brought to her, and the driver to take her by the ear, and order her to lie down. At first she did not like the koomkee to go near her, and retired to a distance, seemingly angry; but when the drivers, who were on foot, called to her, she came immediately, and allowed them to stroke and caress her, as before; and in a few minutes after per- mitted the trained females to be familiar. A driver, from one of these, then fastened a rope round her body, and instantly jumped on her back; which at the moment she did not like, but was soon reconciled to it. A small cord was next fastened round her neck, for the driver to put his feet in, who, seating himself on the neck, in the usual manner, drove her about the keddah, the same as any of the tame elephants. After this, he ordered her to lie down, which she instantly did; nor did she rise till she was desired. He fed her from his seat, gave her his stick to hold, which she took with her trunk, and put into her mouth, kept, and then returned it, as she was directed, and as she formerly had been accustomed to do. In short, she was so obedient, that had there been more wild elephants in the keddah, to tie, she would have been useful in securing them. Mr. Leeke himself then went up, took her by the ear, and bade her lie down ; a command she instantly obeyed. I have known several other instances of elephants being taken a 2d time; and was myself a witness both of the escape and retaking of one, as related in the following account. In June 1787, Jattra-Mungul, a male elephant, taken the year before, was travelling, in company with some other elephants, towards Chittigong, laden with a tciit and some baggage, for our accommodation on the journey. Having come • When elephants were secured in the outlet from the keddah, they bruised themselves terribly. Vide Asiatic Researches, vol. 3. f Koomkees are female elephants, trained for the purpose of se- curing wild ones, and more particularly those large males which stray from the woods, named goondahs. Vide Asiatic Researches, vol. 3. — Orig. VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 440 upon a tiger's track, which elephants discover readily by the smell, he took fright, and ran off to the woods, in spite of the efforts of his driver. On entering the wood, the driver saved himself, by springing from the elephant, and clinging to the branch of a tree under which he was passing; when the elephant had got rid of his driver, he soon contrived to shake off his load. As soon as he ran away, a trained female was dispatched after him, but could not get up in time to prevent his escape; she however brought back his driver, and the load he had thrown off, and we proceeded, without any hope of ever seeing him again. Eighteen months after this, when a herd of elephants had been taken, and had remained several days in the inclosure, till they were enticed into the outlet, there tied, and led out in the usual manner, one of the drivers, viewing a male elephant very attentively, declared he resembled the one which had run away. This excited the curiosity of every one, to go and look at him ; but when any person came near, the animal struck at him with his trunk, and in every respect appeared as wild and outrageous as any of the other elephants. At length, an old hunter coming up and examining him narrowly, declared he was the very elephant that had made his escape about 1 8 months before. Confident of this, he boldly rode up to him, on a tame elephant, and ordered him to lie down, pulling him by the ear at the same time. The animal seemed quite taken by surprize, and instantly obeyed the word of command, with as much quickness as the ropes, with which he was tied, permitted; uttering, at the same time, a peculiar shrill squeak through his trunk, as he had formerly been known to do; by which he was immediately recognized, by every person who had ever been acquainted with this peculiarity. Thus we see that this elephant, for the space of 8 or 10 days, during which he was in the keddah, and even while he was tying in the outlet, appeared equally wild and fierce as the boldest elephant then taken ; so that he was not even sus- pected of having been formerly taken, till he was conducted from the outlet. The moment however he was addressed in a commanding tone, the recollection of his former obedience seemed to rush upon him at once; and without any difficulty he permitted a driver to be seated on his neck, who, in a few days, made him as tractable as ever. These, and several other instances which have occurred, clearly evince, that elephants have not the sagacity to avoid a snare into which they have, even more than once, fallen. The general idea, that tame elephants would not breed, has doubtless prevented trials being made, to ascertain whether, under particular circumstances, this sup- posed reluctance could be overcome. I was however convinced, from observation, as well as from some particular facts, that elephants had their seasons in which they were in heat; I shall therefore first mention the circumstances which induced me to attempt breeding from tame elephants, and then relate the success of the ex- periments instituted for this purpose. The circumstances to which I allude, happened in Jan. 1790, at a keddah near Comillah the capital of Tiperah. Messrs. Henry Buller and Geo. Dowdeswell, of vol. xviii. 3 M 450 PHILOSOPHICAL TRANSACTIONS. [ANNO 1790. Chittigong, being then on a visit at Comillah, accompanied me and several others, to see a herd of elephants which had been lately taken. Our visitors then pro- posed a trial being made, of tying the wild elephants immediately, in the keddah, in the manner practised at Chittigong, instead of waiting till they were enticed, one after another, into the narrow outlet, there to be secured, and led out in the usual manner*. This mode they recommended so earnestly, from a conviction of its superior utility-}-, that Mr. John Buller, to whom the keddah belonged, as- sented to the trial being made, and gave orders for the trained females, and proper assistants, to go directly within the inclosure. Having but few trained females present, it was judged advisable to send in a fine male elephant, taken many years before, and thoroughly broke in, to assist them, as well as to keep the herd in awe. He had no sooner entered the inclosure, and been brought near the herd, than, discovering one of the females to be in heat, impelled by desire, and eager to cover her, he dashed through the herd, regardless of the orders and severe discipline of the driver, and had nearly accomplished his purpose. The driver, being alarmed for his own safety, exerted in vain all his strength, to turn him, and bring him from among the wild elephants; but the drivers of the trained females, coming speedily to his assistance, soon surrounded this furious animal, and separated him from the herd. In resentment however of his disappointment, he attacked a small koomkee, with such violence as completely overturned her and her rider; and had he not been of a particular species, called mucknah, which have only small tusks, he most probably would have transfixed, and killed her on the spot: fortunately, neither she nor her driver received any considerable hurt. This accident prevented the trial being then made, to tie the wild elephants in the manner proposed. Reflecting on the disobedience shown by an elephant remarkably docile, and which had been domesticated for many years, when his passions were excited, and recollecting also, that a wild elephant had covered a female, in Feb. 1778, before many spectators, just after the herd had been secured in the inclosure, I was as- sured in my own mind, that it was not from any sense of modesty, either wild or tame elephants did not gratify their passions in public; but no opportunity offered of prosecuting this inquiry, till 1792. Having then taken on myself the manage- ment of the elephant hunters, a very fine male was caught in Nov.: he was both * Vide Asiatic Researches, vol. 3, article, " Method of catching wild Elephants ;" where this pro- cess is particularly described. + Though fully convinced of this, I could not bring the hunters to adopt the Chittigong method, till the year 1794. After this, during the last 3 years I remained at Tiperah, I did not lose 1 elephant in 20; whereas, by the former method, of tying them in the roomee, near one-third of those taken died in less than a year, in consequence of the hurts they received from their violent efforts to get free, before they could be properly secured. The natives of Tiperah, and in- deed of most parts of India, are extremely attached to old customs j and it was with the utmost diffi- culty I prevailed on the hunters to deviate from the practice of their ancestors, though the method recommended was followed at Silhet, as well as at Chittigong. The method was, simply to sunound a herd, in the first convenient place, with a ditch and palisade j and when this was finished, to send in the koomkees, and proper persons to tie the wild elephants on the spot, and then conduct them, one by one, through an opening in the palisade, from the keddah, as soon as they were tied. — Orig. VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 451 voung and handsome, and also of a most docile disposition ; I therefore promised his driver a considerable gratuity, if he would get him into high order, so that I might have an opportunity of bringing his procreative powers to trial, with a tame female. In March 1793, the driver of a favourite female elephant informed me, that she had then signs of being in heat; and that, if the male and she were kept together, and highly fed, an intimacy would probably soon take place. They were therefore shortly after this brought near to Comillah, where a spacious shed was erected for their accommodation. In the day, they went out together, to feed; they also brought home a load of such succulent food as their drivers and attendants could collect. After their return, they stood together, slept* near each other, and every opportunity was granted them to form a mutual attachment. In the evening, they had each from 10 to 12,1b. of rice soaked in water, to which a little salt was added; and, from the middle of May till the latter end of June, some warm stimulants, such as onions, garlic, turmeric, and ginger, were added to their usual allowance of rice. Long before this however a partiality had taken place, as was evident from their mutual endearments, and caressing each other with their trunks; and this without ceremony, before a number of other elephants, as well as their attendants. Near the end of June, I was satisfied the male would not, even to regain his freedom, quit the object of his regard; I therefore ordered the keepers to picket the female, by one of her fore-legs only, in the house where they stood, but to leave the male at full liberty. Fearful however of hurting their supposed delicacy, and thinking the nearness and sight of the attendants might possibly give umbrage to their modesty, I desired them to remain quiet in a little hut, erected on the outside of the building appropriated to the elephants, where they could see equally well as if nearer. On the evening of June 28, 1793, the male was let loose from his pickets; and soon after he covered the female without any difficulty, though before this she never could have received the male, being taken when very young, about 5-*- years prior to this period. The male was then led quietly to his stall; but early on the morning of the 29th he became so troublesome, that the drivers, in order, as they said, to quiet him, but partly I suspect to indulge their own curiosity, permitted him to cover her a 2d time; which he readily did, before the usual attendants, as well as a number of other spectators. After this, the driver brought me a parti- cular account of the whole process. Though much pleased with the success of the experiment, yet I was rather chagrined he had not given me notice, that I might have been myself an eye-witness; and therefore told him, he should not receive the promised reward, till I had satisfied myself of the fact. * It is always a good sign, when an elephant lies down to sleep, within a few months after he is -taken ; as it shows him to be of a good temper, not suspicious, but reconciled to his fate. Elephants, particularly goondahs, have been known to stand 13 months at their pickets, without lying down to sleep; though they sometimes take a short nap standing. — Orig. 3M 2 Abl PHILOSOPHICAL TRANSACTIONS. [ANNO 17QQ. About 2 in the afternoon of the same day, I was desired to repair to the place where the elephants stood, as the male had been trying to get nearer the female. On this I proceeded to the spot, with my friend Capt. Robt. Burke Gregory: when we arrived, I ordered the male to be freed from his shackles; and, after some toying, and a few mutual caresses, we had the satisfaction to see him cover the female. When the male mounted, he placed 1 of his fore-legs on each side of her spine, with his feet turned to, and pressing against her shoulders, and his trunk over her forehead; supporting himself firmly in this situation, during coition, which he continued nearly the same time, and in the same manner, as a horse with a mare. The female remained perfectly still, during the coitus. When the male had finished, he stood quietly by her side, while she caressed him with her trunk; and as they then appeared well pleased, and gentle as usual, I went up and patted them both, as I had formerly been accustomed to do, without the smallest apprehension. In the evening they were brought home to be fed; and though only a few hours had elapsed since his last embrace, the male seemed inclined to make another at- tempt; to which I would have consented, to gratify a crowd of people then present, had I not now learned, that he had covered the female in the open plain, about 10 in the morning, when going out for food, in spite of the exertions of the drivers and attendants; at least so they alleged, in excuse for having permitted it, contrary to my orders. As he had already covered 4 times in about 1(3 hours, I was afraid a further indulgence might be prejudicial, and therefore would not permit it; especially as Mr. Imhoff, to whom he then belonged, was absent. That gentle- man however returned 8 days after; but when the 2 elephants were brought to- gether, in order that Mr. ImhofFs curiosity might be indulged with so novel a sight, the female, being no longer in heat, was so uncivil as to give the male a kick in the face, when he was using what she then thought improper liber- ties; nor did she afterwards permit him to cover her, though, when standing to- gether, they mutually indulged in a few caresses. During the time they were kept together, the male never showed signs of his passions being excited, by any exudation from the ducts of the glands near his temples; which is generally considered as the sign of a male elephant being pecu- liarly ready for the female. This however I am inclined to believe is a vulgar error; as not one of the male elephants I have seen cover, in a domestic state, nor any of the males which were caught singly, or rather entrapped, by their desire to have connexion with the tame females, had at those times the smallest appearance of such an exudation. Had this happened in any 1 instance, during my residence in Tiperah, I think I must have known it; for when this exudation takes place, the elephant has a dull heavy look, and it is dangerous for strangers to go near him. I have seen elephants in this situation, after they had been many years caught; but though they were then said to have their passions excited, I have never known one to cover during the continuance of this exudation : nor have elephants, so far as I YOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 433 have been able to observe, any particular seasons of love, like horses and cattle. Of 5 instances of elephants covered at Tiperah, one received the male in Feb., another in April, a 3d in June, a 4th in Sept., and the 5th in Oct. Eesides these, an at- tempt was made by a tame male, to cover, in the month of Jan. a wild female, then in heat*. When the female is in heat, the parts of generation show it, by an unusual fulness of the labia; and if she is placed near a male, she endeavours by caresses to excite his desires -j-. After the female had been covered by the male, as has been just related, there being then no other female ready, he was placed with an elephant which had had a young one about 4 years before this, and some months ago was reported to have been put in heat. It was thought, after some trial, that she was likely to permit him to cover, as she caressed him occasionally, and roused his passions; but she would not allow him to gratify his desire. The drivers, tired of this coyness, and stimulated perhaps by the hopes of another gratuity, were so brutal as to tie her, and let the male make an attempt upon her, while tied. His attempt however was to no purpose; though he continued his efforts till he appeared to be quite exhausted. This being told me, I severely reprimanded the people; and ordered the female to be left at full liberty to reject or receive the male, as she might think proper. Here however was positive proof, that the male would have effected his purpose by force, when he found he could not obtain it in any other way. He re- mained at Comillah till Oct. 1793, without my being able to procure a female that was in heat; he was then sent to Calcutta. I now became extremely solicitous about the health of the female which was covered in June; and gave particular directions not to overheat her, but merely to give her as much food and exercise as were likely to keep her in the best condition, as she was now known to be pregnant. In 3 months after she was covered, she became fuller, her flesh softer, and her breasts began to swell. These marks of her being with young were so evident to the driver, that he mentioned them of his own accord; which convinced me that an elephant, 3 months after conception, may be known by the keepers to be pregnant. She had always been a favourite, from having been the gift of my worthy and respected friend Mr. John Buller^, as well as for her gentle and docile disposition; and now I had hopes of her going her full time. She was 7 feet 3 inches high, when covered; but after this increased so fast, not in bulk only, but also in height, as to exceed 7 feet 8 inches, before she brought forth. On the 1 6th of March, 1795, she produced a fine male; just * Many pregnant females are taken every year at Tiperah, and produce young ones in the different months : this clearly shows that there are no particular seasons during which the females are in heat. — f It may be proper to observe, that the penis of a full grown elephant is from 2 feet 4 to 2 feet 6* inches in length, and from 14 to 1 6 inches in circumference. I caused the penis of 2 males to be measured, after their passions were excited, in order to ascertain the real size. On some occasions, I have seen the penis absolutely touch the ground, when the elephant has been walking} but it must be recollected, that the hind legs of an elephant are very short, in proportion to his size. % Now one of the Members of the Board of Revenue, at Calcutta, — Orig. 454 PHILOSOPHICAL TRANSACTIONS. [ANNO 17 QQ. 20 months and 18 days after she was first covered. The young one was 35-L inches high; and had every appearance of having arrived at its full time, being the largest I had known produced in Tiperah. We have many young produced every year, by the females which are taken while breeding, and these seldom exceed 34 inches; this however may be owing to the weak and reduced state the mothers are brought to, while breaking in. The young of the elephant, at least all those I have seen, begin to nibble and suck the breast soon after birth; pressing it with the trunk, which by natural instinct they know will make the milk flow more readily into the mouth, while sucking. Elephants never lie down to give their young ones suck; and it often happens, when the dam is tall, that she is obliged for some time to bend her body towards her young, to enable him to reach the nipple with his mouth; consequently, if ever the trunk was used to lay hold of the nipple, it would be at this period, when he is making laborious efforts to reach it with his mouth, but which he could always easily do with his trunk, if it answered the purpose. In sucking, the young elephant always grasps the nipple, which projects horizontally from the breast, with the side of his mouth. I have very often observed this; and so sensible are the attendants of it, that with them it is a common practice to raise a small mound of earth, about 6 or 8 inches high, for the young one to stand on, and thus save the mother the trouble of bending her body every time she gives suck, which she cannot readily do when tied to her picket. Tame elephants are never suffered to remain loose; as instances occur of the mother leaving even her young, and escaping into the woods. Another circum- stance deserves notice: if a wild elephant happens to be separated from her young, for only 2 days, though giving suck, she never afterwards recognizes or acknow- ledges it. This separation sometimes happened unavoidably, when they were en- ticed separately into the outlet of the keddah. I have been much mortified at such unnatural conduct in the mother; particularly when it was evident the young ele- phant knew its dam, and, by its plaintive cries and submissive approaches, solicited her assistance. Here it may be observed, that a female was believed to have gone 21 months and 3 days; being supposed to have been covered on Jan. 13, 1788, some days before she was driven into the inclosure. When I made particular inquiry as to the real time she was taken, the daroga, or superintendant of the hunters, said it was in Jan.; but the dydars, or principal hunters, declared she was among the herd taken in Feb. following, and was probably the same elephant Mr. Buller, Captain Hawkins, and many others, saw covered on the 9th and 10th of that month. Perhaps some days prior to this she might have been covered in the woods, before she was brought into the inclosure; but as a herd was taken in each of those months, and not kept separate, and 2 years had nearly elapsed before I thought of making any inquiry, it was impossible for me to determine in which of those months she was really taken ; and the only motive I then had for endeavouring to VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 455 ascertain this point, was to form some probable conjecture as to the period of an elephant's gestation, which has now been ascertained, in the instance before re- lated. Early in Sept. 1795, the female that had been covered, and had bred under my own observation, was known to be in heat; this was less than 6 months after bring- ing forth. Learning, at the same time, that the Rajah of Cudwah, a principal Zemindar of the province, had a very large male that had been in the family near 20 years, from the time he was about 5 years old, I sent a messenger, requesting the elephant might be sent to Comillah, which request the Rajah immediately com- plied with. To prevent any interruption from the numbers of spectators, the ele- phants were put into a small inclosure, on the 17th of Sept.; the female was picketed by 1 leg, and the young one, to which she was giving suck, was tied to a tree at some distance, fearing, if permitted to run about, he might receive some injury. After a few caresses from the female, the male at length effected his pur- pose, and covered her twice the same evening. As the intention of the male ele- phant's visit was known in the district, and a few days had elapsed since the 2 elephants were brought together, in order to make them acquainted, the number of spectators was greater than on any other similar occasion. She was afterwards covered, several times, on the 20th of the same month; the male, in this case, being admitted after an interval of 3 days, though formerly, in June, 17Q3, she refused him when only 2 had elapsed. She again proved with young; and, in Nov. 1796, being myself in a bad state of health, and under the necessity of returning to Europe, I sent her to Lucknow, together with her young one, at the request of my friend captain David Lumsden : though she was then very big, she was still giving suck. About a month before that period, I got my friend, Mr. Stephen Harris, to permit a female of his to be covered; the same which had, in 1793, rejected the attempts of the male to cover her contrary to her inclination. Another messenger was dispatched to Cudwah, for the Rajah's elephant, which was again sent to Comillah. He covered her repeatedly, on the 14th, 15th, and 16th of Oct. 1796, before many Europeans, as well as natives; and, the last time he covered her, it was evidently contrary to her inclination; so that, in fact, he used force to effect his purpose, and held her so firmly, that the marks of the nails of his fore-feet were deeply imprinted on her shoulders. Having mentioned a sufficient number of instances, to prove the ability, as well as the inclination of the elephant, to propagate his species in a domestic state, and that without any signs of modesty, and having ascertained the period of gestation to be 20 months and 1 8 days, it may be necessary to observe, that it is a difficult matter to bring a male, which has been taken about the prime of life, into good condition to act as a stallion ; for, being naturally bolder, and of a more ungovern- able disposition, than the female, he is not in general easily tamed, till reduced very low; and it requires considerable time, as well as much expence and attention before he can be brought into such high order as is requisite. He must also be o/ 456 PHILOSOPHICAL TRANSACTIONS. [ANNO 17 QQ. a gentle temper, and disposed to put confidence in his keeper; for he will not readily have connexion with a female, while under the influence of fear or distrust. Of this I have seen many instances; nor do I recollect one male elephant in ten which had been taken after having attained his full growth, much disposed to have connexion with a female. This is a most convincing proof, that those males which are taken early in life, and have been domesticated for many years, more readily procreate their species than elephants taken at a later period. In their wild state however they show no reluctance; for, besides all the males that are entrapped, from their desire to have connexion with the trained females which, though not in heat, are carried out to seduce them, several instances have occurred, of wild ele- phants covering, immediately after being taken, in the keddah. On the 3d of April, 17 Qo, a very fine male elephant covered a "female twice, in the midst of the herd, and before all the hunters. On the 4th, I saw him at- tempting to cover a third time, when he was suddenly disturbed, by the noise the hunters made to drive away some of the herd which had come too near the palisade. In consequence of this interruption, he threw down first 1 and then another small elephant, and gored them terribly with his tusks, though they came between him and the female only for their protection: he had, before this, killed 4, and wounded many others. When the poor animals were thrown down, conscious of their im- pending fate, they roared most piteously ; but notwithstanding their prostrate situa- tion, and submissive cries, he unfeelingly and deliberately drove his tusks through, and transfixed them to the ground; yet none of the large elephants, not even the dams of the sufferers, came near to relieve them, or seemed to be sensibly affected. This savage animal had been then confined 4 days iu the inclosure, along with the herd, on a very scanty allowance of food, and could have but very little hope of escaping; yet here his passions were stronger than his fears. It was on account of this savage disposition that the hunters had asked permission to shoot him, before I had either seen him or the herd, and thence judged he was a goondah *, that had lately joined. Having never before known any elephant killed willingly, in the keddah, by the larger males, and having no idea that he would commit such ter- rible havock, I unluckily refused to grant their request, being desirous to save so stately an elephant. When the palisade was finished, I got him tied, and led out; * From this instance, as well as many concurring circumstances, I am convinced that these goondahs generally leave the herd of their own accord, and join it when they think proper, or are induced to it from a female being in heat ; yet it has been supposed, that they are driven from the herd, at an early period of life, by their seniors This appears improbable, as it is not often that very large males are taken with a herd of elephants ; for, depending on their own strength, they stray singly, or in small parties, from the woods into the plains, and even to the villages; and it is in these excursions they are taken, by means of the trained females. As these goondahs are much larger, and stronger, than the males generally taken with the herd, it is not probable they would submit to be driven from it, unless at an early period. I have seldom seen, in a herd of elephants, a male so large as may be commonly met with among two or thee goondahs ; but if these last were driven from the herd when young, the very reverse would be observed. — Orig. VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 457 but, not brooking restraint, he languished about 40 days, after he was secured, and then died. In the course of this narrative, I have, in general, related only such particulars concerning the elephant as came within my own knowledge, and which were either not known, or not published. To enter into a particular history of the elephant was not my intention ; and though the procreation of tame elephants has been proved, yet the expence incurred by breeding them, may deter others from making attempts of this kind. But it opens a field of curious inquiry to the naturalist; and, now that the facility with which it may be done is ascertained, it suggests itself as a mode by which the breed of elephants may be improved, in size, strength, and activity. In this way, any expence which might be incurred, would more than repay itself, in the future benefits to be derived from a superior breed of elephants. VI. On the Decomposition of the Acid of Borax or Sedative Salt. By Lawrence de Crelly M. D., F. R. S., &c. From the German, p. 56. The salt called borax, so useful in various manufactures and arts, and hitherto imported only from Thibet and Persia, or in small quantities from Tranquebar, has ever excited the attention of natural philosophers. This attention was principally directed to the acid contained in it, called sedative salt; its other component part, the alkaline salt, (soda or natron), being better known, and found in many other natural productions, either alone, or in conjunction with other acids. The acid above-mentioned has hitherto been discovered only by Hofer, in the lagone of Castelnuovo ; by Martinovich, in the petroleum of Gallicia, mixed with alkaline earth ; and by Mr. Westrumb, near Luneburg. The scarcity of this acid, and its being found only in the substances and situations above-mentioned, occasioned a supposition, in the minds of those who minutely observe and examine the course of nature, that it is not a simple substance, but is formed afresh from a variety of other substances, previously decomposed, by a singular coincidence of operative causes ; and consequently that it belongs to compounds. Numerous have been the experiments made by chemists, who supposed they had formed this salt by composition : some described experiments, which they declared to have succeeded with them, though they always failed, when attempted by others ; from which Leonhardi concludes, that nothing more can be expected from any similar attempts to produce sedative salt. I was surprized that these chemists had never, so far as I knew, examined the subject by the way of analysis, and endeavoured to decompose the sedative salt already formed by nature. Indeed no great hopes of success could be entertained, as daily experience shows, that though this salt be kept fluid, in the hottest fire, for many hours together, till it becomes a vitrified substance, yet when it is afterwards dissolved in distilled water, the solu- tion is complete, without any residuum, and it then shoots into crystals of pre- vol. xvin. 3 N 458 PHILOSOPHICAL TRANSACTION*. [ANNO 17QQ. cisely the same salt as before. Notwithstanding all this, when I reflected, that borax is generated only in certain climates of the east, and that its acid is found only in particular substances and situations, as has been already mentioned, I could not but suppose the latter to be the produce of a new formation. This being pre- mised, I considered maturely in what manner the decomposition of this new and extraordinary compound might be attempted. Admitting the composition to be formed by the coalition of a number of different substances, it seemed not impro- bable that an acid, penetrating into and dissolving the whole mass, would rather associate with some than with others of its various component parts, and thus produce a separation or change of the latter. Besides, as the sedative salt, strong as its operation is, in a high degree of heat, on almost all neutral salts, has but a faint taste of acid, it might be supposed, that its acid is contained within some unknown species of earth, intimately combined ; or within some sort of inflam- mable matter ; or, according to a phrase used in the new system, there might be a deficiency of acid matter ; that therefore some more powerful acid would probably separate and dissolve the earthy particles, destroy or change the inflammable matter, or impart the acid it might be supposed to want. My choice, among the different acids, was fixed on that particular one, which, though not always quick in its operation, never fails to penetrate deep into all soluble substances, is nearly related to all inflammable bodies, and possesses an abundance of acid matter : I mean the oxygenated muriatic acid, prepared with manganese. In the application of this menstruum, I resolved to follow the prac- tice established by the constant experience of both ancient and modern chemists; which has taught us, that difficult decompositions of parts closely united, are more easily effected by a gentle, long continued, digestive heat, and repeated distillation of the same menstruum, than by a heat which is more violent, and operates more quickly. I first made some preliminary experiments, in order to judge what pro- bability there might be of success. Exper. 1. I poured 1-^oz. of the above-mentioned acid on 2 dr. of sedative salt, in a retort, to which I adapted a proper receiver, and then placed the mixture in a gentle digestive heat, of from 140° to 200° of Fahrenheit. The fluid was distilled over very slowly, and the salt was dry on the 3d day. The salt in the retort seemed unchanged; nor had the marine acid lost any thing of its usual smell. — Exper. 2. I poured the distilled fluid out of the receiver on the same salt, and exposed them to the same degree of heat as before. The salt again became dry on the 3d day, but there was yet no appearance of any change. — Exper. 3. I re- peated the same process a 3d time. I now perceived during the distillatory diges- tion, several bright yellow spots on the salt, as it ascended the sides of the retort, resembling well-formed am moniacal flowers of iron; more of which I discovered after the entire exhalation of the fluid. — Exper. 4. The above change induced me to repeat the distillation ; and I then perceived, not only as many, but a much VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 45Q greater number of bright yellow spots, some of which were even much darker in colour, and approaching to brown. A change had now evidently taken place, which change increased on every repetition of the process; I therefore judged I might follow this direction with confidence. But, with a view to use the greatest accuracy and precaution in my proceedings and observations, I resolved to begin my work over again. First, I procured some ounces of sedative salt, which had been obtained from borax by means of vitriolic acid; and then prepared 2 quarts of the above-mentioned oxygenated muriatic acid, by distilling 3 parts of muriatic acid with 1 part of the purest manganese, in the usual manner; this I preserved in a cool dark place. Thus, the substances used in the following experiments, were always of the same nature. Exper. 5. I poured 3 oz. of the oxygenated muriatic acid on 4- oz. of the seda- tive salt, in a white glass tubulated retort. I used such a retort, that, in fre- quently pouring back the distilled fluid, I might not have to lute afresh the several vessels, after every distillatory digestion. For the same reason also, I chose a tubu- lated receiver, the tube of which gradually terminated in a point, in shape of a funnel. This tube passed into a phial, placed in such a manner that all the fluid passing into the receiver dropped immediately into the phial, the joinings of which were closed with bladder. To close the tube of the retort, I did not think it right to use a waxed cork, though it closes very tight, because it might be corroded; and also because the vapours, dropping from the cork, might carry some fat and oily matter back into the retort. For the same reason, I would not use any greasy lute; but closed the joints of the glass stopper, which fitted remarkably close, with a ring of fine sealing-wax, closely pressed on it, but which could easily be disengaged, after my work was done, while the retort was still warm : and as I was even afraid of an oily lute about the joints of the receiver, I closed them up with a ring of very fine white clay, which I fitted to them as exactly as possible, by pressure; letting it stand several days to dry, and then carefully filling up all the cracks. Having made this previous arrangement, and put the above-mentioned ingredients together, I suffered them to remain cold for 24 hours; at the end of which, the salt was not entirely dissolved, but, on the application of heat, the whole became a clear fluid.* The degree of heat in the sand was from 180° to 240°, by which the fluid evaporated very slowly. During this operation there ascended, or rather crept up the sides of the retort, a considerable quantity of salt, in very loose flowers, rising pretty high above the fluid, increasing by de- grees, and chiefly occupying that half of the retort which received a greater degree # This appeared to me so striking, that I endeavoured to obtain a confirmation of it. I made a similar mixture, in the same proportions, which was not dissolved so long as it remained cold j but was dissolved by heat. When the solution cooled, a small part of the salt, and a larger as the cold in- creased, precipitated, which was dissolved again by a fresh application of heat. But with the degree of heat I employed, no more than 1 part of salt would dissolve in 6 parts of the acid.— Orig. 3 n 2 460 PHILOSOPHICAL TRANSACTIONS. [ANNO 1799- of heat than the other; but never the opposite or colder half. In 4 days, the fire being extinguished towards the evening of the last, the fluid had evaporated, so as to leave the salt apparently dry. - After cooling for some time, the bladder on the phial was moistened by water, and the vessels were separated; the sealing-wax also having been removed, and the stopper taken out, the distilled fluid was poured back, through a glass funnel, on the salt, without disturbing the lute. Exper. 6\ As soon as the fluid was added, the salt at the bottom began by de- grees to dissolve: that on the sides of the retort did the same, after kv was heated, but soon began to form again: the solution appeared of a yellowish hue. In general however, the whole experiment took the same course as in exper. 5, and the smell, both of the salt and the fluid, seemed to be unchanged. The only difference was, that the former did not appear like salt, the crystallization on the sides excepted, and in single detached crystals, but something like a white, uni- form, spongy, and as it were earthy mass. The fluid was now again taken from the phial, as in exper. 5, and poured back on the salt. Exper. 7, 8, and 9. During the 3d distillation, bright yellow spots began to appear on the white flowers; and after the salt at the bottom had become dry, similar spots appeared on it, particularly on the lower surface. The fluid was again, for the 4th time, poured on the salt, and distilled; when the yellow spots and flowers increased in number. This was also the case in the 5th distillation. Exper. 10. The fluid obtained by the last experiment, which had changed a little in smell, and had acquired a particular scent, almost as if some sebacic acid had combined with the muriatic, was poured on the salt as before. The number of yellow spots, which had also become of a darker hue, was considerably in- creased. The salt had now been exposed, ever since the 5th exper. for 32 days, to the digestive distillation ; and the intermediate time between each distillation had been longer or shorter, in proportion to the degree of heat, and to the time of kindling and extinguishing the fire. As I now found that business of im- portance would prevent me from continuing my labours for some months, I poured 2 other ounces of the muriatic acid on the salt, besides the fluid so often drawn off by distillation, and left the mixture at rest. Exper. 11, 12, 13, 14. When my business was finished, I again undertook the distilling of the mixture, which had been so long digesting in the cold, for the 7th time, and obtained the same results as in exper. 10. Nor was there much difference observed in the 12th, 13th, and 14th experiments. Exper. 15. I now poured the fluid obtained by the 14th exper. on the salt, which had acquired more and more yellow spots, brighter in hue, and then pro- ceeded as before, till the salt became dry ; on which, when the retort was cool, I poured 1 oz. 3 dr. of the muriatic acid, in addition, and allowed the mixture to digest gently for some days. Exper. 16. In this 12th distillation, there appeared a large quantity of flocculent sublimate, looking almost like branches, hanging VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 46l down, and in many places of a yellow colour; it extended even into the neck of the retort, and almost covered the interior aperture of the tube. — Exper. 17. The 13th distillation produced the same phenomena. On the lowermost surface of the mass of salt, many light-brown spots appeared, as soon as the fluid was so much evaporated that no more of it could be seen on the salt. — From all these circum- stances, I now believed the mass of salt, by a digestion of 22 days, and 7 distilla- tions, from exper. 11 to 17, that is, by a digestion of 54 days, and 13 distilla- tions, in the whole, to be so far decomposed, as to admit of a separation of some of its constituent parts. I therefore supposed I might leave off applying only digestive warmth, and proceed to a greater degree of heat. Exper. 18. Having poured out the fluid obtained by exper. 17, and replaced the phial, I increased the degree of heat. By this the retort became quite obscured, first by fumes, and afterwards by a quantity of white sublimate, attaching itself to all its sides, which however had not the appearance of common sedative salt. As I increased the heat, the sublimate became dark in colour; afterwards became black and frothy: and at length ran down the sides of the retort, in different places, like thick oil of hartshorn, the retort being almost wholly blackened by it. — Exper. lg. While the retort was still warm, I poured into it the fluid obtained by exper. 17, having first warmed it a little; when, almost in the same instant, a very agreeable phenomenon took place. Crystals, perfectly white, shot forth suddenly, and all at once, from every part of the black mass, covering the sides of the retort. The distillation being continued, these crystals were at length dissolved, and entirely re- moved. The supernatant fluid was, as usual, almost colourless. When the mass of salt appeared dry, the fire was increased, as in exper. 18, and the same appear- ances as above related took place: first, the sublimate appeared white, then black, frothy, and flowing down the sides. — Exper. 20. I proceeded, as in exper. 19, to pour back the distilled fluid. Instantly a number of the whitest crystals shot forth from the black ground, forming small groups; but the retort was cracked. Exper. 21.1 therefore took all the vessels asunder, and shook the retort well, till whatever hung on its sides was dissolved; then distilled the fluid in another retort, till the mass of salt appeared quite dry. I now put the retort into a crucible, sur- rounded it with sand, fitted another receiver to it, and placed the crucible in an open fire. First, some sublimate was produced, towards the neck of the retort, but which vanished as the heat increased, and then a small portion of fluid, hardly more than a dram, or a dram and a half, which appeared to smell a little of the sebacic acid. At the bottom of the retort was a blackish mass, a, and likewise some sublimate, b, which, by its varied appearance, seemed to be of a two-fold nature. Exper. 22. The residuum taken out of the broken retort had a spongy appear- ance, and swam on water; it had a blackish colour, and weighed 3 dr. 10 gr. Being exposed to the air, the blackish colour became lighter, and inclining to grey. When 462 PHILOSOPHICAL TRANSACTIONS. [ANNO 1 7QQ. digested in 16 parts of distilled water, in the usual temperature, for 2^ days, it did not all sink to the bottom; and after being digested with heat for 20 hours, it was not entirely dissolved: that part which sank, was of a blackish brown. More water was then added, and it was made to boil for 2 hours ; it was afterwards placed on a paper filter, the weight of which was previously ascertained, and edulcorated with boiling distilled water, till at last a proportion of 26 parts of water to the substance had been used. After all the fluid, a, had passed through, and the filter, with the residuum, had been dried in a heat of 212°, for an hour and a half, the residuum, (3, weighed, exclusive of the filter, lQgr. — Exper. 23. The fluid, a, obtained by exper. 21, was suffered to evaporate gradually, and yielded 3 dr. 10 gr. of a white transparent salt. — Exper. 24. This salt, obtained by exper. 23, was put into a small retort, and exposed, in a crucible filled with sand, to an open fire. It became of a blackish-brown colour, yielded some sublimate, a, about 5 gr., a small portion of fluid, b, and a blackish-brown residuum, c, which became lighter in colour, on being exposed to the air. — Exper. 25. The fluid, b, of exper. 24, smelled like marine acid, and precipitated nitrate of lead. — Exper. 26. The residuum, c, of exper. 24, by the addition of some water, became whiter, and was dissolved ; more water having been added, it was digested with heat, by which the matter was dissolved. The solution being afterwards filtered, I obtained 2 dr. 4 gr. of white salt : the residuum on the filter weighed 4 gr. — Exper. 27. This salt, exper. 26, was again exposed to the fire; when it yielded from 20 to 30 drops of acid liquor, 4 gr. of sublimate, and a residuum which, being dissolved, yielded 1 dr. 33 gr. of salt, and left 24 gr., c, on the filter. The same salt, obtained by Exper. 26, being distilled, became of a brownish grey colour; and, besides a few drops of fluid, yielded not quite 2 gr. of sublimate. On treating the residuum with water, it yielded 68 gr. of salt, and there were not quite 2 gr. left on the filter. Exper. 28. On treating these 68 grs. of salt in the same manner, they yielded a few drops of fluid, and 2gr. of sublimate: after filtration, there remained 48 gr. of salt, and a residuum of hardly Hgr. — Exper. 29. The same salt, treated in the same manner, yielded a few drops, and a little sublimate; and after filtration, 35 gr. of salt, and a residuum of hardly 1 gr. — Exper. 30. On treating these 35 grs. of salt in the same way, they yielded, besides a very small quantity of fluid, and of sublimate, 24 gr. of salt, and about \ gr. of residuum. — As I now dis- covered that the quantity of salt was continually decreasing, and some coal sepa- rating from it, I thought it superfluous to endeavour to decompose the above 24 gr. any further. Exper. 31. The residuum, (3, of Exper. 22, was light, blackish, and like coal. I now poured common concentrated muriatic acid on 3 grs. of it, and digested the mixture for 42 hours, in a considerable degree of heat, but no dissolution was apparent. I then added smoking nitrous acid, and digested it for 24 hours, till it VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 403 boiled, without any apparent dissolution. I added about 2 gr. of sugar, but with- out effect, except that its colour became yellowish. I now boiled the fluid, till it all evaporated in reddish-yellow vapours: there remained a very black, thick, gluti- nous mass, smelling like burnt sugar. Having added 3 oz. of water, the greatest part of the blackish matter rose to the surface, and the water appeared only a little tinged. The fluid part indeed became brown by boiling; but after rest and subsi- dence, it again got clear. I filtered it, a; then poured 2 oz. more distilled water on the residuum, and, after digesting, boiling, and filtering, added the filtered fluid, b, to the former, a. After this treatment, there remained 2gr. of residuum, c. Exper. 32. Having caused the fluid a, b, of exper. 31, to evaporate, it yielded a salt greyish-yellow mass, which very quickly attracted the moisture of the air. Being again dissolved in water, and saturated with pot-ash, a considerable quan- tity of whitish earth was precipitated, very much resembling talc. Exper. 33. The residuum, c, of exper. 31, which, besides its insolubility and lightness, had much of the external appearance of coal, was now thrown on melted nitre, and it deflagrated. I placed a 2d crucible with melted nitre close to it, and having, at the same moment, thrown into one the above-mentioned residuum, and into the other a quantity of common charcoal pulverized, I could not observe the smallest difference in effect. Very little difference was also apparent, as to the residuum, (3, of exper. 22, c, of exper. 24, and that of the following experiments. Exper. 34. To obviate the objection, that sedative salt alone would perhaps deflagrate with melted nitre, I made that experiment also, but in vain. Not the smallest deflagration took place, even when both were melted together for many hours. — Exper. 35. Another objection may be made, namely, that in distilling the muriatic acid from manganese, part of the latter had passed over with the acid ; and, in the frequent distillations of the sedative salt, had been deposited on it, and thus deflagrated. But, on throwing fresh pulverized or solid manganese, either such as is usually sold, or quite pure, heated to redness, into melted nitre, not the smallest deflagration took place. Exper. 36 to 50. Instead of the interrupted heat used in the foregoing experi- ments, I now exposed 4-oz. of the salt, with 3 oz. of the oxygenated muriatic acid, to a continued heat of between 200° and 300° of Fahrenheit. The fluid had nearly evaporated in 24 hours. I changed the phial, towards the close of the operation, for another, that the former might be gently heated, and the fluid by that means be poured back, with the greater safety, on the warm salt, through the tube of the retort. In this manner, during an uninterrupted fire of 14 days, the acid was 14 times distilled, and returned on the salt. On the 3d day, yellow spots appeared. On the 4th, some particles of oil or fat were discovered, swimming on the surface of the fluid in the phial; which particles, after cooling and emptying the phial, adhered to its sides, so as to obscure its transparency, 464 PHILOSOPHICAL TRANSACTIONS. [ANNO 1799. More or less of these oily particles were discovered in every successive operation; and the oily matter, adhering to the inside of the glass, increased considerably. Exper. 5 1 . When the fluid was distilled, the receiver was changed, and the fire increased. A considerable quantity of sublimate was obtained, pretty white in colour, as was also the surface of the mass of salt at the bottom of the retort; but lower down it was almost of a light ash-grey. After the sublimate ceased to arise, I diminished the fire. Exper. 52. On the mass of the former experiment, I poured the fluid, obtained by exper. 49, and continued a gentle digestion. I very soon perceived something rising towards the surface, and swimming on it: after some hours, it appeared to be a thick wrinkled skin, like fat, or a skin of mould, increasing in size, till it covered the whole surface. White spots of sublimate appeared on it, but it did not sink. It assumed gradually a fine lemon colour, and some yellow matter, though not in large quantity, ascended the sides of the retort. The fluid having been gently distilled, and the receiver changed, I placed the retort in an open fire; on which, more sublimate soon appeared; but, not long after, it all vanished, and the retort lost its transparency. The mass contained in it began to rise, first gently, and then violently, especially in the centre, in large frothy bubbles. The distillation was finished, after obtaining 1 dr. of fluid, and when the frothy bubbling had ceased. The retort being broken, that part where the bubbling had been strongest, was found to be black ; the upper surface being covered with a thin greyish matter, under which a solid, compact, and almost vitrified substance ap- peared. On this I poured water, and dissolved it in the usual manner; filtered it, let it evaporate, and treated it as described above, exper. 22 — 30. Exper. 53. I obtained a white salt, a, and some coal, b, which deflagrated briskly with nitre, in nearly the same proportions as throughout the series of expe- riments described from exper. 20 to 33, which I will not repeat, on account of the little variety observed in them ; one of them however deserves to be distin- guished from the rest. — Exper. 54. I put 6 gr. of the coal, b, of exper. 53, in 3 dr. of common muriatic acid, and digested them for 2 days, till the acid had gradually evaporated. I then added 1 dr. of the same acid, with 1 scruple of nitric acid, and when they had evaporated, boiled the residuum full half an hour in distilled water. By this process, I obtained a red solution ; and, having saturated it with mild alkali, a sort of skin rose to the surface, with some small pieces of a fat slippery substance, a. A considerable quantity of loose earth, b, was also precipitated, of a light brown colour. — Exper. 55. On throwing the floating pieces* a, of exper. 54, into a solntion of caustic alkali, they dissolved; the solution had a reddish-brown colour. — Exper. 56. With the same solution of caustic alkali, I covered the light brown earth of exper. 54. As the solution changed its colour to a reddish brown, the earth gradually became perfectly white. — Exper. 57. To ob- serve the affinity of other acids to the sedativesalt, I poured6 dr. ofnitrous acid on2dr. of the salt, with 10 dr. of the oxygenated fore-mentioned muriatic acid; digested the VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 465 mixture, and distilled it, in 24 hours, with a gentle heat. On the fluid swam a white compact substance, and some small particles of the same kind lay at the bottom, which however rose, on the application of heat, and swam about with the rest. Exper. 58 to 63. I poured the whole distillation back on the salt, and, by means of a digesting heat, again drew off a fluid, which appeared covered with a thin fat skin. I then poured the fluid back; distilled it again, and thus repeated the pro- cess 3 times more. No phenomenon particularly remarkable appeared, except that the thin fat skin became more inconsiderable, and at last seemed almost to vanish. Exper. 64. The salt separated from the fluid, by the gentle distillation in exper. 63, emitted now, by the force of additional heat, dark red vapours, as is usual in strong nitrous acid. When the distillation was at an end, the retort was exposed to an open fire; but, during this operation, no black matter appeared; nor was any coal separated from the mass, on dissolving it in distilled water.* — Exper. 65. I now tried the effect of a mixture of 4 dr. of strong vitriolic acid, and ] 2 dr. of the muriatic acid, repeating the usual digestion and distillation 6 times. I shall pass over other circumstances, and only mention, that after the 6th distillation of the fluid, a stronger heat, and at length an open fire, was applied; but hardly any fluid was produced, though the fire was so violent, that the Whole mass appeared to be melted down into one uniform compact substance. — Exper. 66. The vessels having cooled, the mass was of a light milky colour throughout, without the least mix- ture of brown or black, or any other indication of coal.-j- Being some time exposed to the air, it became moist, and for a long time attracted much water, which I caused to run off. At last it remained pretty dry; but the mass seemed to have diminished, by at least 4- part. Here I shall stop, for the present, in the description of my experiments; which sufficiently tend to prove, in a general way, the decomposition of sedative salt, and to show, that one of its component parts is inflammable matter, which may be converted into coal. I obtained of true coal, mixed with some earth, exper. 33 and 54, according to the above-described experiments, (exper. 22, 26 — 30), 30f gr« m tne whole; and by other experiments, often repeated, in general, l-±- gr. more or less. Every other substance liable to be changed into coal, as gum, tartar, sugar, &c. suffers this change by a gentle heat, and deflagrates with nitre, in the degree of heat necessary to melt the former. But sedative salt can bear a red heat for many hours, without showing any signs of becoming coal, of burning, or of deflagration. Astonishing phenomenon! What menstruum preserves it so se- curely against the assault of force, in a dissolved state, and yet suffers itself to be * Here the nitrous acid seemed to destroy, and carry off, the inflammable matter, sooner than it could become coal ; as it had before occasioned the oily and fat substance to vanish, in the beginning of this experiment. — Orig. f Perhaps here also the remark contained in the former note holds good : yet I am rather of opinion, that the vitriolic acid did not operate with sufficient strength to separate the component parts.— Orig. VOL. XVIII. 3 O 466 PHILOSOPHICAL TRANSACTIONS. [anno 1799. separated from it by more gentle means? What power exists here, to protect the inflammable particles, which afterwards turn to coal, so effectually against a degree of heat which nothing else can resist? Of what nature is the salt obtained in con- junction with the coal? These are all questions which excite great interest, but which are not easily answered. How far I have been successful in resolving them, some subsequent Essays will show ; which I shall have the honour to lay before the r. s., as soon as I shall have sufficiently repeated the experiments I have already made. VII. A Method of Finding the Latitude of a place, by means of Two Altitudes of the Sun, and the Time Elapsed between the Observations. By the Rev. W. Lax, A.M.) Lowndes's Prof, of Astronomy, Cambridge, p. 74. I hope the following method of determining the latitude, by means of 2 alti- tudes of the sun and the time elapsed between the observations, will be found not less convenient for nautical purposes than the rules which are commonly employed. But I would rather recommend it in those cases where rigid accuracy is required, and the astronomer is provided with no better instrument for taking the sun's alti- tude, than a Hadley's sextant of the most improved construction. The process will be neither difficult nor tedious; and, if the observations are made with proper exactness, I conceive the latitude will generally be obtained within a few seconds of the truth. In the spherical triangle, whose sides are the complements of the latitude, de- clination, and altitude, let z represent the angle at the pole, and t its tangent; z the azimuth, and t its tangent; l the latitude, and x its cosine, radius being unity; then, if the altitude and declination remain constant, we shall have L = xiz, and consequently 1 will vary as tz, when the increment of x, compared with x itself, is inconsiderable. Hence, if the abscisse of the Fig. ] . curve abcd, fig. 1, be always proportional to z, and its ordinate to t, the area gb, intercepted between any 2 of these ordinates may represent the increment of the latitude corresponding to the increment of the time eg. Let abed, fig. 2, be another curve, whose abscisse ae is always equal to ae in the preceding figure, but whose ordinate eb is pro- portional to /, the tangent of the hour-angle; then will the area gb vary as gb, at small distances from the meri- dian, and of course may represent the increment of the A latitude. Now, to prove this, we have only to show that t and t, when both are small, bear to each other a given ratio. Let s and £ be the sine and cosine of the azimuth ; s and positive), (-y )•— J an(l consequently - = (l ) . -, when radius is unity; but = (m* — — ) . -At;, when radius is m. Now - may be considered as the in- crement of the hyperbolic log. of y, and therefore, with its proper modulus, may represent the area which is the object of our investigation. We may suppose the other side of the equation to be the square of the cosine of the arc whose sine iSv/ — x into the increment of the hyperbolic log. of a1, divided by the square of the radius; and if, instead of taking this log. with the hyperbolic, we take it with Briggs's modulus, we must then consider - as the increment of the log. of y, according to the same system. But -? being equal to — (when i is only 1'), it will vary as s; and therefore, if its value be determined according to Briggs's system, when s is equal to radius, and be denominated v, its value in any other case will be expressed by — . Hence, to obtain the log. of the area gc, the quantity with which we are imme- diately concerned, we must find the log. value of — , and divide it by 2; we must then take out the log. cosine of the arc whose log. sine is equal to the quotient; and, having multiplied it by 2, we must add the product to the constant log. of v (3.1015), and the log. tangent of the supposed latitude, rejecting thrice the log. radius. But if \/ — be greater than radius, which must necessarily be the case when the azimuth is greater than a right angle, we must then consider rrn" « _. ,, c tu„ i. 4. „r *i ...i ^ • yrm3 VI m2 as the square of the tangent of the arc whose secant is \/—, observing * in other respects the directions before given. The quantities r and s are both em- ployed in the first computation, from the result of which we also obtain y; and consequently this operation will not be attended with much trouble. The above instructions, it is manifest, are given on the supposition of r and s having the same sign; but if the declin. and latit. should not be of a similar deno- fini Vic mination, then will our expression become (m2 -| ) . — , and we must consider m1 -| as the square of the secant whose corresponding tangent is y^ — . With this exception, the process will be the same as when the tangents r and s are both affirmative. The preceding formula naturally suggests to us another method of finding the log. area gc; and as some perhaps may think this more eligible than either of the former, I shall take the liberty of explaining it. When the latit. is given, the area gc, it is obvious, must invariably preserve the same magnitude at all distances 472 PHILOSOPHICAL TRANSACTIONS. [ANNO 179Q. from the meridian; and consequently the area gc, which is proportional to it, must likewise remain constant. If therefore we can ascertain this area when the hour- angle is supposed to vanish, we may employ it when the sun is at any distance from noon. Let us now conceive the declin. to be equal to nothing; then will our ex- pression for the area gc become jj> ; and consequently, (since the tangents of the azimuth and hour-angle vanish in the ratio of their sines, or of the sines of the opposite sides in the triangle alluded to before), we shall have the area gc = —, when the sun is on the meridian. But this area is always the same when the lati- tude is given, whatever be the sun's declination, and therefore may always be repre- sented by ^ = - X 7 = -7-; ana* tne area gc WM De generally expressed by ~ x cos. o men a tit. ^en the hour-angle does not exceed the limits which have been cos. of declin. ° recommended. Hence, if we add together the constant log. 3.1015, the log. radius, and the log. cosine of the merid. altitude, and from their sum subtract the log. cosines of the latit. and declin. we shall obtain the log. value of gc. It will be necessary perhaps to meet an objection, which some may be inclined to urge, against the method of deducing the hour-angle in terms of the cosine, when this angle is very small. But it should be recollected, that with the angle itself we have no immediate concern, the accuracy of our conclusion depending entirely on the accuracy with which the area corresponding to any particular incre- ment of time can be determined. Now this area, whatever be the sun's distance from the meridian, will be nearly proportional to the increment of the latit. and consequently its magnitude is totally unconnected with that of the hour-angle. A given error in the quantity which expresses this area will equally affect our conclu- sion, whether the angle be 2, or whether it be 20 degrees. But let us inquire what effect will actually be produced, by admitting an error of half an unit in each of the log. cosines whose difference is equal to the area gc; and of course in some in- stances, an error of an unit in the area itself, on any particular supposition of latit. and declin. We have only to ascertain the ratio which this area bears to unity: for the same ratio will the correction of the latit. bear to the error in our result. If the latit. for instance, be 50°, and the declin. 10°, on the same side of the equator with the latit. then, radius being unity, i, the increment of the hour-angle, will equal — = - = (g being the sine of the hour-angle, and « the cos. of *T cos. 50° x 4- the altit.) r^ X ~L— - =11' nearly, when z is 5°; and we have seen that, ' cos. 50° go at any other distance from the meridian, the incremental area will be of the same magnitude. Hence, subtracting the log. cosine of 5° from that of 5° ll', we get the difference equal to 1238; and consequently the error in our approximation will be to the error in the assumed latit. as 1 : 1238, when the log. cosines are carried to 7 places of decimals. But, when the zenith distance of the sun, at his greatest VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 473 altit. is very small, and there is also a considerable uncertainty with respect to the latit. this error will probably become of more importance, and we may find it necessary to guard against it. Now it is manifest that, by diminishing the multi- ple which the area gb is of the area gc, exactly in the same proportion we shall di- minish this error. Mr. L. further adverts to the methods of correcting or avoiding certain small in- accuracies, which however may commonly be omitted, or obviated ; he then pro- ceeds : I have hitherto supposed that this method is only to be adopted, when the sun, at each observation, is within 1 5° of the meridian ; or, to speak, more accu- rately, when both the azimuth and the hour-angle are so small, that we may con- sider their tangents as bearing a given ratio to each other ; and indeed these limits should never be transgressed, when it can possibly be avoided ; for we have seen that, whatever be the method employed, the smaller the hour^angle, the greater is the exactness with which the lat. is determined. Sometimes however it will be im- possible to make both, or perhaps either of our observations within the distance re- commended ; but even in these cases our rule may be conveniently applied. It has already been demonstrated that we can never be subject to any material error in consequence of the inequality of the areas gb and gb, except when the zenith-dis- tance of the sun, at his meridian altitude, is very small ; and for this case an effectual remedy has been provided. Before concluding the theory, it may be observed, that though I have directed the altitudes to be taken on different sides of the meridian, it is by no means re- quisite that we should invariably adhere to this precept. We have seen the reason indeed why it is expedient, in most instances to prefer this method, being generally calculated to produce a much greater degree of exactness in the result. This how- ever is not always the case ; for, if one of the observations be made beyond the dis- tance originally prescribed, it is of little importance whether the 2d altitude be taken on the same side of the meridian, or not. But it will sometimes be im- possible to make the observations on different sides of noon ; and hence it becomes necessary to inquire in what manner the real latitude may be discovered in these cir- cumstances. The clock gives us the interval between the observations equal to ae — ae ; and by computation we find ag and ag, and thence we deduce eg — eg, the difference between the errors in time. Having then assumed, without any re- gard to accuracy, 1 portions of time, corresponding to the 1 observations, whose difference is the same as the difference between the errors before determined, and which are to each other in the inverse ratio of the hour-angles, we must increase or diminish them both equally, till we get the areas in the first table of the same mag- nitude, and then we may conclude that we have obtained the proper value of each. The directions which have been given for the prevention of errors in the former case, when the altitudes are taken on different sides of the meridian, are very easily accommodated to the present ; and it would therefore be superfluous to bestow any further consideration on them. VOL. XVIII. 3 P 474 PHILOSOPHICAL TRANSACTIONS. [ANNO 1799. From a review of the inaccuracies to which this method, in particular cases, may be liable, it appears that none of them can ever be of sufficient importance to affect the mariner. If he only computes the time with each of the altitudes and the lati- tude by account, and an incremental area with the greatest altitude and the former latitude varied 10', the correction will generally be deduced within much less than a second, and in the most unfavourable circumstances within a minute of the truth. But the astronomer, in every instance, even when the latitude and declination are nearly equal and of the same kind, by adopting the precautions which have been re- commended, may be assured of a result perfectly exact. If however he should entertain any doubts on this point, he might easily compute a second value of the incremental area with the latitude already determined ; and this, it is evident, would necessarily produce a conclusion not less accurate than if it were obtained from the direct method. The most satisfactory way of proving the utility of this rule, will be to suppose a particular latitude and declination ; with these to compute the altitudes, when the sun is at 2 given distances from the meridian ; and thence to deduce the latitude, by an application of our own principles. And for this purpose, Mr. L. here gives 4 several examples, the calculation of which he gives, at length; and then adds the following remarks. 1 . All the altitudes that are taken on the same side of noon, tend only to correct the error which may be supposed to exist in the greatest of these altitudes, and can have no effect in removing any inaccuracy to which the greatest altitude on the other side of the meridian may be subject. Hence we must take more than one altitude on each side of noon, if we are desirous of obtaining a very exact con- clusion. 2. When some of the observations are made in the morning, and others in the afternoon, the smaller the hour- angle, in every instance, the more favourable it will be for our purpose. But if we cannot procure an altitude on each side of the meridian, we ought to make one observation when the hour-angle is as large as possible, and with this all the rest should be separately combined. We must be cautious however not to let the sun be too near the horizon, lest the apparent alti- tude should be affected by the uncertainty of the refraction. 3. If the clock were to furnish us with the true time, we might combine to- gether any 2 observations made within the proper limits, without applying to the first table, and deduce a very exact correction. Should there even be a small error in the supposed time, we might still proceed in the same manner, without being liable to any material inaccuracy, provided the difference between the hour-angles was not very considerable. The error indeed occasioned by adopting this method of finding the 2 areas, and taking a mean between them for the value of gb, may easily be determined in any particular case. If t and t' be the respective tangents of the smaller and greater hour-angles, and i their difference ; i the error of the clock in minutes of time ; and i the whole error in the time computed with the VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 475 greater altitude ; then will the error in the result be to the whole correction of the i L /• \ fk — tk . tk th tz lyS'—dx. r . lat. ( l ) : : - : tz : : —- : — - : : -— : rrr x X l : : 7-5 X tz : s L. \ ' 2 2 15TA 2 15Ay^ y This error will consequently be equal to — ' ; and hence it appears that, if we had pursued this method in the last example, and there had been an error of a mi- nute in the time given by the clock, there would not have been an error of a single second in the conclusion. 4. If the time were determined by equal altitudes, and one of them were to be employed in computing the area gb, it is manifest that we should entirely exclude the error which has just been considered. It would be necessary however, in order to correct by the 2d observation, any inaccuracy that may have occurred in reading off at the first, to move the index, and then bring it apparently to the same posi- tion again, before we proceeded to take the 2d altitude. A 5th example is then calculated according to these remarks ; after which is given a short specimen of the tables before mentioned. The process observed in this table will require very little explanation. The first column contains the observed double altitudes, as they were read off from the sex- tant ; the 2d contains the corresponding times given by the clock ; the third con- tains the times from noon determined, with sufficient exactness, by taking half the interval between the first and last observations, (in which the altitudes are equal,) and supposing this to be the time elapsed between the first observation and the sun's reaching the meridian. The fourth column is formed of the log. cosines of the hour- angles taken immediately from the argument of the first table ; and the last column exhibits the latitudes deduced from every two corresponding altitudes, and is in- tended to show the agreement between these results. It is not necessary that we should employ the tables in this operation : for we may take the log. cosines of the hour-angles from Taylor's Logarithms, after the time is reduced into degrees, minutes, and seconds ; and, by dividing the area gb = 7537, by the area gc = 203, (the natural number belonging to the log. 3.3081,) we shall obtain the correction required. VIII. A Fourth Catalogue of the Comparative Brightness of the Stars. By Wm» Herschel, LL.D., F.R.S. p. 121. After the usual list of the stars, are added the following notes. Notes to Auriga. — y Is (3 Tauri. f Is 32 Camelopardali. h " Oct. 5, 1798. The time of this star, in the observation of Flamsteed, vol. 2, p. 18Q, is marked :: ; but it cannot be much out, as the star seems to be in the place assigned to it by the British catalogue." 6l. The ra in the Atlas Ccelestis requires a correction of — 42'. Notes to Draco.-*-i Is 87 Ursae. 3P2 476 PHILOSOPHICAL TRANSACTIONS. [ANNO 1799. i and 6 Were never observed by Flam steed, but are in La Caille's Catalogue of northern stars. n M. de la Lande says the star is not to be found. See Mr. Bode's Ast. Jahr- Buch for 1795, page 198. I observed this star in a sweep of the heavens, June 2, 1788. Its brightness was estimated Sept. 11, 1795 ; Sept. 24, 1796; Sept. 30, 1796 ; and Dec. 28, 1798 ; so that, if M. de la Lande is sure no cloud intervened when he looked for it, we may suspect it to be a changeable star. a. The British catalogue requires + 30' in ra. (v}/2) The expression " 35 — 40 + 41" in my estimation of brightness, means that, with the naked eye, the star is a very little brighter than 40 and 41 together, taken as one star. For they are so near each other, that the eye alone cannot dis- tinguish them from a single star. The British catalogue gives them 3' farther asunder than they ought to be according to Flamsteed's observation, p. 463. See also Mr. Bode's Ast. Jahr-Buch for 1785, p. 173. b The estimation M 40 — 4l" was made with a 7-feet reflector, power 460. u Does not exist. Flamsteed has no observation of it. My double star 11, 31, called 56 Draconis, is a star situated between 59 and 50, about 1-f degree from 59 towards 50.* on the contrary, we are led by numberless phenomena to believe, that the level of the waters in our globe is much below what it was in former periods ; we must therefore conclude, that the forest here described grew in a level high enough to permit its vegetation ; and that the force, whatever it was, which destroyed it, lowered the level of the ground where it stood. There is a force of subsidence, particularly in soft ground, which, being a natural consequence of gravity, slowly though perpetually operating, has its action some- times quickened and rendered sudden by extraneous causes, for instance, by earth- quakes. The slow effects of this force of subsidence have been accurately remarked in many places ; examples also of its sudden action are recorded in Almost every history of great earthquakes. The shores of Alexandria, according to Dolomieu's observations, are a foot lower than they were in the time of the Ptolemies. Donati, in his natural history of the Adriatic, has remarked, seemingly with great accuracy, the effects of this subsidence at Venice ; at Pola, in Istria ; at Lissa, Bua, Zara, and Diclo, on the coast of Dalmatia. In England, Borlase has given, in the Phil. Trans, vol. 48, p. 62, a curious observation of a subsidence, of at least 1 6 feet, in the ground between Sampson and Trescaw islands, in Scilly. The soft and low ground between the towns of Thorne and Gowle, in Yorkshire, a space of many miles, has so much subsided in latter times, that some old men of Thorne affirmed, " that whereas they could before see little of the steeple of Gowle, they now see the churchyard wall."* The instances of similar subsidence which might be mentioned, are innumerable. This force of subsidence, suddenly acting by means of some earthquake, seems the most probable cause to which the actual submarine situation of the forest we are speaking of may be ascribed. It affords a simple easy explanation of the matter; its probability is supported by numberless instances of similar events ; and it is not liable to the strong objections which exist against the hypothesis of the alternate de- pression and elevation of the level of the ocean ; an opinion which, to be credible, requires the support of a great number of proofs, less equivocal than those which have hitherto been urged in its favour, even by the genius of a Lavoisier.-f- The stratum of soil, l6 feet thick, placed above the decayed trees, seems to re- move the epoch of their sinking and destruction, far beyond the reach of any histo- rical knowledge. In Caesar's time, the level of the North Sea appears to have been the same as in our days. He mentions the separation of the Wahal branch of the Rhine, and its junction to the Meuse ; noticing the then existing distance from that junction to the sea ; which agrees, according to D'Anville's inquiries, J with * Gough's edition of Camden's Britannia, t. 3, p. 35. f Mem. de 1'Acad. de Paris, 1789, p. 351. — — * D'Anville Notice des Gaules. p. 461, — Orig. 3 a 2 484 PHILOSOPHICAL TRANSACTIONS. [ANNO 1 7Qg. the actual distance. Some of the Roman roads constructed by order of Augustus, under Agrippa's administration, leading to the maritime towns of Belgium, still exist, and reach the present shore.* The descriptions which Roman authors have left us, of the coasts, ports, and mouths of rivers, on both sides of the North Sea, agree in general with their present state ; except in the places ravaged by the inroads of this sea, more apt, from its form, to destroy the surrounding countries, than to increase them. An exact resemblance exists between maritime Flanders and the opposite low coast of England, both in point of elevation above the sea, and of internal struc- ture and arrangement of their soils. On both sides, strata of clay, silt, and sand, often mixed with decayed vegetables, are found near the surface; and in both, these superior materials cover a very deep stratum of bluish or dark-coloured clay, unmixed with extraneous bodies. On both sides, they are the lowermost part of the soil, existing between the ridges of high lands,-}- on their respective sides of the same narrow sea. These two countries are certainly coeval; and whatever proves that maritime Flanders has been for many ages out of the sea, must, in my opinion, prove also, that the forest we are speaking of was long before that time destroyed, and buried under a stratum of soil. Now it seems proved, from his- torical records, carefully collected by several learned members of the Brussels Academy, that no material change has happened to the lowermost part of maritime Flanders, during the period of the last 1000 years. J I am therefore inclined to suppose the original catastrophe which buried this forest, to be of a very ancient date; but I suspect the inroad of the sea which un- covered the decayed trees of the islets of Sutton, to be comparatively recent. The state of the leaves and of the timber, and also the tradition of the neighbouring people, concur to strengthen this suspicion. Leaves and other delicate parts of plants, though they may be long preserved in a subterraneous situation, cannot remain un- injured, when exposed to the action of the waves and of the air. The people of the country believe, that their parish church once stood on the spot where the islets now are, and was submerged by the inroads of the sea; that, at* very low water, their ancestors could even discern its ruins; that their present church was built to supply the place of that which the waves washed away; and that even their present clock belonged to the old church. So many concomitant, though weak testimo- nies, incline me to believe their report, and to suppose that some of the stormy inundations of the North Sea, which in these last centuries have washed away such large tracts of land on its shores, took away a soil resting on clay, and at last un- covered the trees which are the subject of this paper. * Nicol. Bergier. Hist, des grands Chemins des Romains. E4 de Bruxelles. vol. 2, p. 109. — Orig. + These ridges of high lands, both on the British and Belgic side, must be very similar to each other, since they both contain parts of tropical plants in a fossil state. Cocoa nuts, and fruits of the areca, are found in the Belgic ridge. The petrified fruits of Sheppey, and other impressions of tropical plants, on this side of the water, are well known. X Vide several papers in the Brussels Memoires j also Journ. de Pbys. t. 34, p. 401.— Orig. VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 485 Meteorological Journal, kept at the Apartments of the R. S. By order of the President and Council, p. 157. Six's Therm, without. Thermometer without. Thermometer within. Barometer.* Hygrometer. Rain. 1798. « bo 0 ■4-J •*-> o a°d made the following ob- servations on the imperfectly formed children. The eldest was 13 years of age, of a most uncommon bulk, which appeared to be almost wholly composed of fat ; his body, round the waist, was equal to that of a fat man, and his thighs and legs in proportion ; he was 4 feet high ; his breasts as large as those of a fat woman ; the mons veneris loaded with fat ; no penis ; a praeputium -fth of an inch long ; and under it the meatus urinarius, but no vagina. There was an imperfect scrotum, with a smooth surface, without a raphe in the middle, but in its place, an indented line ; it contained 2 testicles, of the size they are met with in the foetus. He was very dull and heavy, almost an idiot, but could walk and talk : he began to walk at a year and 4- old. The younger one was 6 years old, uncommonly fat, and large for his age ; more an idiot than the other, not having sense enough to learn to walk, though his limbs were not defective. The external parts of generation dif- fered in nothing from those just described, except in the prepuce being an inch long. He had a supernumerary finger on each hand, and a supernumerary toe on each foot It is curious that the mother of these 2 children, so like in their imperfections, should have had a perfectly formed child between them ; and it leads me to men- tion, that the Polish dwarf, Count Boruwlaski, who was in England in 1786, stated, that in his family the children had been alternately dwarfs, of which there were 2, he and his sister ; the intermediate child having grown to the common size. The immense accumulation of fat, and the uncommon size of these chil- dren, accords with the disposition to become fat, so commonly met with in the free-martin. The species of malformation of the organs of generation in which there is really VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 491 a mixture of parts, or an evident attempt towards it, is less common than those we have mentioned. Mr. Hunter has given several instances of it in the neat cat- tle, where the mixture of male and female organs was in different degrees. In 2 free-martins, imperfect testicles were found in the situation of the ovaria ; and, in a 3d, an appearance like both testicles and ovaria was met with, close together, in the situation of the ovaria. He also gives the dissection of an hermaphrodite ass ; in which there were substances resembling both testicles and ovaria in the abdo- men. Mr. Hunter never met with an instance of this kind in the dog ; and I have not found one in any record which I have examined. I shall therefore state the following history of a case which has fallen under my own observation, as it proves, that a mixture of the generative organs sometimes occurs, in a species of animal in which it had not been before met with ; and, as the dog is more domes- ticated than almost any other quadruped, the occurrence must be rare indeed, otherwise it could not have escaped notice. A favourite dog of Lord Besborough's, which had lived in the family for many years, was observed to have no teats, and never to have been in heat, though, to appearance a perfectly formed bitch in all other respects : those circumstances being made known to Sir Jos. Banks, he requested, that when the animal died, it might be sent to him. This happened last summer ; and I had an opportunity of exa- mining the organs of generation, which exhibited the following appearances. There was not the smallest appearance of teats on the skin of the belly : so that, in this particular, it differed both from the male and female ; nor was there the least trace of any thing like the gland of the breast, under the skin. The clitoris was very large, being three-quarters of an inch long, and half an inch broad ; the orifice of the meatus urinarius was unusually large, as if it was intended for a common passage to the bladder and vagina ; so that the external parts were only the clitoris, meatus urinarius, and rectum. Internally, in the situation of the ovaria, were 2 imperfectly formed small testicles, distinguished to be such by the convolutions of the spermatic artery ; from these passed down an impervious chord, or vas deferens, not thicker than a thread, to the posterior part of the bladder, where they united into one substance, which was nearly 2 inches long, and termi- nated behind the meatus urinarius. The other parts of the animal were naturally formed. When the testicles were cut into, they appeared to have no regular glan- dular structure. In this animal, the clitoris was the only part of the female organs that was completely formed. What rendered the parts a decided mixture of male and female organs was, the testes being in the place appropriated for the ovaria and the ligamentous substance, to which the vasa deferentia were connected, some- what resembling an impervious vagina. The clitoris, in this instance, could not be considered as an imperfect penis, since the bone, the distinguishing mark of the dog's penis, was wanting. In Haller's account of hermaphrodites, before-mentioned, there is the history of a kid, in which there was a mixture of male and female organs, illustrated by 3e 2 4Q2 PHILOSOPHICAL TRANSACTIONS. ("ANNO 17QQ. an engraving. They were very similar to those of this dog : the imperfect testicles were in the same situation ; but there was a pervious canal or vagina, that divided like the uterus, into 1 horns, which extended to the testicles ; there were also vesi- culae seminales. In the Memoirs of the Royal Acad, of Sciences of Paris for 1720, there is a very accurate description, by M. Petit, of a similar mixture of organs in the human species. The person had wholly the character of a man, but was of a delicate constitution : he was a soldier, and died of his wounds. The appearance of the penis is passed over ; but the scrotum, not containing testicles, drew M. Petit's attention ; and, in the dissection, he found testicles in the situation of the ovaria, attached to 2 processes, continued from an imperfect vagina, but having vasa deferentia, which passed, in the usual manner, to the vesiculae seminales. The vagina communicated with the urethra, between the neck of the bladder and the prostate gland. A case of mixed organs is mentioned in Dr. Baillie's Morbid Anatomy : the person was 14 years of age, had the breasts of a woman, and no beard. The cli- toris and meatus urinarius had the natural appearance, but there were no nymphae, and the labia pudendi were unusually pendulous, containing a testicle in each of them. The vagina was nearly 1 inches long, and terminated in a blind end. She never menstruated, and had a masculine appearance. This appears to have been the reverse of the case mentioned by M. Petit : in this, the external parts were those of the female, in which were contained the testicles ; while, in the other, the internal parts were those of the female, with the testicles attached to them. There is still another mixture of the organs of the female with those of the male, which is probably the most rare in its occurrence ; this is, an hermaphrodite bull, probably a free-martin, partaking so much of the bull as to have the male organs capable of propagating the species, and an udder capable of secreting milk. The glands which secrete milk, though in themselves not organs of generation, entirely belong to them, and form a part of the female character, sufficiently obvious to connect them intimately with the present subject. That an animal not a per- fect female, should have glands which secrete milk, or indeed that an animal truly female, without having had young, should give milk, is so extraordinary, that even written evidence respecting it requires confirmation to entitle it to credit ; in this respect, the following fact must be considered as perfectly satisfactory. An instance of an hermaphrodite bull, whose udder secreted milk, occurred lately in Poland. The animal came into the possession of Mr. Brookes, who procured it near Grodno, in the year 179^, and carried it to St. Petersburg, where it died in the following year ; unfortunately, no examination was made after death. While the animal was at St. Petersburg, both Dr. Rogerson and Dr. Rogers had oppor- tunities of examining it with a considerable degree of accuracy ; and the following account is taken from their description, with which I have been favoured by Dr. Rogerson, who is now in London. The animal was under the usual size of neat cattle, and is stated by Mr. Brookes to have been about 1 5 years old ; it was in a VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 4Q3 weakly state, and Mr. Brookes told Dr. Rogerson, that he had much difficulty in making it bear the journey from Grodno, a distance of about 800 miles, and was obliged to give it the most nourishing diet, which was principally ground malt. In its general appearance, the male character predominated, particularly in the head, horns, neck, shoulders, and organs of generation. The flanks and hind-quarters had a greater resemblance to those of the cow. The penis was of the ordinary size, and had the common appearance ; the preputium had the tuft of hair at the orifice, as in the bull. The urine was ejected through the penis. It had an udder in the common situation, which was smaller, and more globular, that that of the cow, and its teats were less pendulous. Dr. Rogers found one of the testicles, by pressing on the udder, but was unable to detect the other. There was an external orifice in the situation of the vagina, but so small as not to appear capable of re- ceiving more than the point of the fore finger. Dr. Rogerson thinks, from its appearance, that it never could have admitted the male, much less have brought forth a calf, which had been asserted, but without any proof whatever. Mr. Brookes, who is now in this country, admits that it had never received the male, or brought forth young, while in his possession ; but asserts that it had several times covered the female, and had begot 5 calves. This assertion, Dr. Rogerson thinks highly deserving of credit. The udder contained milk capable of giving cream, but the quantity was very small. When Dr. Rogerson was present, only 1 oz. could be procured ; but he was told that at other times a tea-cupful was drawn. Mr. Brookes states, that he saw an English pint milked at one time. As the teats of the bull are in the same situation as those of the cow, it became an object of inquiry, whether any males of that tribe of animals, that were not hermaphrodites, had ever been known to give milk; and I find there are two instances recorded in the Phil. Trans, of wethers having given suck. One is on the testimony of the Rev. Dr. Doddridge, who states that a lamb was nourished by the milk, and when the teats were pressed, milk came out *. The other is on the testimony of Mr. Kirke, of Cookridge, in Yorkshire. He mentions, that Sir William Lowther had a lamb suckled by a wether. The lamb sucked during the whole summer, and after it was weaned, milk could be pressed from the teats : each side of the udder was the size of a hen's egg. This account is dated Sept. 28th, 16*94. He gives a 2d relation, in Nov., stating that the udder was reduced in size, but there was still some milk in it, and no appearance of the animal being an hermaphrodite -f~. A case is also recorded in the Phil Trans., voL 41, p. 813, of a man giving suck to a child 2 months old; this however is not stated with sufficient accuracy to allow any stress being laid on it, though it would have been improper not to have noticed it in this place. In considering the influence of the testicles on the constitution of the male which is rendered so evident by contrasting it with those cases in which the testi- cles are imperfect, it leads to a supposition, that the ovaria may have a similar in- * Phil. Trans, vol. 45, p. 502.~Orig. f phil. Trans, vol. 18, g. 26&— Orig. 494 PHILOSOPHICAL TRANSACTIONS. [ANNO 17 QQ, fluence on the constitution of the female ; and that, when the ovaria are imper- fectly formed, or when testicles are substituted for them, though the external parts are decidedly female, the person may grow up, deprived of that feminine character which the constitution would have acquired, if the ovaria had been capable of pro- ducing their influence on the body. To this cause may be attributed the unnatural bias which some women have shown, to pass through life in the character of men. The circumstance of some women, after the time of breeding is over, at which period the influence of the ovaria may be considered as lost to the constitution, approaching nearer to the male in appearance, and acquiring a beard ; also the female pheasant and duck *, in several instances, at the same period of their life, acquiring the feathers which distinguish the male, so as to be mistaken for males, is in favour of such an opinion. The histories of monsters which have superfluous parts, as that of the child with the double head -)~, and all others of the same kind, lead to the opinion of 2 or more foetuses having been contained in 1 ovum, similar to 2 yolks in 1 egg ; and that, from some circumstances having taken place in utero, certain parts of 1 of the foetuses were prevented from coming to perfection, and were absorbed ; while those that remained became connected to the other foetus. When monsters are. imperfect, there is no difficulty in accounting for any organ, or other structure, not having been completely formed ; but, that the ovaria should be wanting, and their place supplied by testicles, is not to be explained on the same principle. The testicles being substituted for the ovaria, and the ovaria themselves entirely wanting, is probably the most curious circumstance that is met with, in the structure of these hermaphrodites ; and as many important discoveries in the animal economy have been suggested from the examination of monstrous productions, it naturally leads to the inquiry, whether there is any thing in the original formation of the parts, which can account for so strange an occurrence. The only mode in which it can be explained, as far as I am able to judge, appears to be the following. By supposing the ovum, previous to impregnation, to have no distinction, but to be so formed as to be equally fitted to become a male or female foetus ; and that is * The following account of a duck of this kind was sent me by Mr. Rumball, surgeon, at Abingdon, in Berkshire. The duck was bred by Mr. Cator, of Norwood, in Surrey, in the year 1781. It conti- nued to lay, and to hatch its young, till the year 1789 ; when the curled feathers, peculiar to the drake, made their appearance in its tail. From this period, she not only left off laying, but frequently attempted to tread the other ducks, both in the water, and on the ground j and they courted her in return. This was particularly observed on the 19th of August, 1791, when she trod a duck in the water, and fell off on her side, as drakes usually do ; and they both began washing themselves immediately after, as is cus- tomary on these occasions. She never afterwards suffered a drake to come near her. Though the plu- mage changed, the voice continued the same, which is very different from that of the drake. This cir- cumstance first attracted Mr. Rumball's notice, and made him doubt of its being really a drake. On the 14th of Oct. 1793, at the request of Mr. Rumball, this duck was sent to Mr. Hunter, and died on the 18th, 2 days after Mr. Hunter's death. On examination, the organs of generation were those of a perfect duck. The skin is stuffed, and preserved in Mr. Hunter's collection. — Orig. | Phil. Trans, vol. 80, p. 296, and vol. 89, p- 28.— Orig. VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 4Q5 the process of impregnation which marks the distinction, and conduces to produce either testicles or ovaria, out of the same materials. The following circumstances are in favour of this opinion. The testicles and ovaria are formed originally in the same situation, though the testicles, even before the foetus has advanced to the 8th month, are to change their situation, to a part at a considerable distance. The clitoris, in foetuses under 4 months, is so large as to be often mistaken for a penis. Preparations to show the size of the clitoris at this age are preserved in Mr. Hunter's collection ; and M. Ferrien mentions it, with a view to explain an erroneous opinion which prevailed in France *, that the greater number of mis- carriages between 3 and 4 months, have been remarked to be males ; which mis- take arose from the above circumstance. The clitoris originally appears therefore equally fitted to be a clitoris or penis, as it may be influenced by the ovarium or testicle. In considering this subject, it is curious to observe the number of secondary parts, which appear so contrived that they may be equally adapted to the organs of the male or female. In those quadrupeds whose females have mammae inguinales, the males have also teats in the same situation ; so that the same bag which con- tains the testicles of the male, is adapted to the mammae of the female. In the human species, which have the mammae pectorales, the scrotum of the male serves the purpose of forming the labia pudendi of the female, and the preputium makes the nymphae. The male has pectoral nipples, as well as the female ; and in many infants, milk, or a fluid analogous to it, is secreted ; which proves the exist- ence of a glandular structure under the nipple. This circumstance, when added to the instances already related, of an hermaphrodite bull, and of wethers giving suck, affords a strong presumption that the rudiments of the mammae exist in the male, and in some few instances have been brought to perfection, either by an original mixture of organs, early emasculation, or other changes with which we are at present unacquainted. If it is allowed that the sex is impressed on the ovum at the time of impreg- nation, it may in some measure account for the free-martin occurring when 2 young are to be impressed with different sexes, at one impregnation ; which must be a less simple operation, and therefore more liable to a partial failure, than when 1 or any greater number of ova are impressed with the same sex. It may also ac- count for twins being most commonly of the same sex ; and when they are of dif- ferent sexes, it leads us to inquire whether the female, when grown up, has not in some instances less of the true female character than other women, and is not inca- pable of having children. It is curious, and in some measure to the purpose, that in some countries, nurses and midwives have a prejudice, that such twins seldom breed. This view of the subject throws some light on those cases where the testicles are substituted for the ovaria ; since, whenever the impregnation fails in stamping the ovum with a perfect impression of either sex, the part formed will neither be an * Mem. de l'Acad. Royal des Sciences de Paris, 1767, P' 330. — Orig. 496 PHILOSOPHICAL TRANSACTIONS. [ANNO 1799. ovarium nor a testicle, sometimes bearing a greater resemblance to the one, some- times to the other; and may according to circumstances, either remain in the natural situation proper to the testicle, whether it is the scrotum of the male, or the labia pudendi of the female. XT. An Inquiry concerning the JVeight ascribed to Heat. By Benjamin Count of Rumford, F.R.S., M.R.I. A., &c. p. 179- The various experiments which have hitherto been made with a view to deter- mine the question so long agitated, relative to the weight which has been supposed to be gained, or to be lost, by bodies on their being heated, are of a nature so very delicate; and are liable to so many errors, not only on account of the imper- fections of the instruments made use of, but also of those, much more difficult to appreciate, arising from the vertical currents in the atmosphere, caused by the hot or the cold body which is placed in the balance, that it is not at all surprizing that opinions have been so much divided, relative to a fact so very difficult to ascertain. It is a considerable time since I first began to meditate on this subject, and I have made many experiments with a view to its investigation; and in these experiments, I have taken all those precautions to avoid errors, which a knowledge of the various sources of them, and an earnest desire to determine a fact which I conceived to be of importance to be known, could inspire; but though all my researches tended to convince me more and more, that a body acquires no additional weight on being heated, or rather, that heat has no effect whatever on the weights of bodies, I have been so sensible of the delicacy of the inquiry, that I was for a long time afraid to form a decided opinion on the subject. Being much struck with the experiments recorded in the Transactions of the r. s. vol. 75, made by Dr. Fordyce, on the weight said to be acquired by water on being frozen; and being possessed of an excellent balance, belonging to his most Serene Highness the Elector Palatine Duke of Bavaria; early in the beginning of the winter of the year 1787, — as soon as the cold was sufficiently intense for my pur- pose, I began to repeat those experiments, in order to convince myself whether the very extraordinary fact related might be depended on; and with a view to removing, as far as was in my power, every source of error and deception, I proceeded in the following manner. Having provided a number of glass bottles, of the form and size of what in England is called a Florence flask, blown as thin as possible, and of the same shape and dimensions, I chose out from among them 2, which, after using every method I could imagine of comparing them together, appeared to be so much alike as hardly to be distinguished. Into one of these bottles, which I shall call a, I put 4107.86 grains Troy of pure distilled water, which filled it about half full; and into the other b, I put an equal weight of weak spirit of wine; and, sealing both the bottles hermetically, and washing them, and wiping them perfectly clean and dry on the outside, I sus- pended them to the arms of the balance, and placed the balance in a large room, VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 4g7 which for some weeks had been regularly heated every day by a German stove, and in which the air was kept up to the temperature of 6l° of Fahrenheit's thermo- meter, with very little variation. Having suffered the bottles, with their contents, to remain in this situation till I conceived they must have acquired the temperature of the circumambient air, I wiped them afresh, with a very clean dry cambric hand- kerchief, and brought them into the most exact equilibrium possible, by attaching a small piece of very fine silver wire to the arm of the balance to which the bottle which was the lightest was suspended. Having suffered the apparatus to remain in this situation about 12 hours longer, and finding no alteration in the relative weights of the bottles, they continuing all this time to be in the most perfect equilibrium, I now removed them into a large uninhabited room, fronting the north, in which the air, which was very quiet, was at the temperature of 290, p. ; the air without doors being at the same time at 27°; and going out of the room, and locking the door after me, I suffered the bottles to remain 48 hours undisturbed, in this cold situation, attached to the arms of the balance as before. At the expiration of that time, I entered the room, using the utmost caution not to disturb the balance, when, to my great surprize, I found that the bottle a very sensibly preponderated. The water which this bottle contained was completely frozen into one solid body of ice ; but the spirit of wine, in the bottle b, showed no signs of freezing. I now very cautiously restored the equilibrium, by adding small pieces of the very fine wire of which gold lace is made, to the arm of the balance to which the bottle b was suspended, when I found that the bottle a had augmented its weight by 3 , ^o4 part of its whole weight at the beginning of the experiment; the weight of the bottle with its contents having been 48 J 1.23 grains Troy, (the bottle weighing 703.37 grains, and the water 4107.86 grains), and it requiring now TVW parts of a grain, added to the opposite arm of the balance, to counterbalance it. Having had occasion just at this time to write to my friend, Sir Charles Blagden, on another subject, I added a postscript to my letter, giving him a short account of this experiment, and telling him how " very contrary to my expectation" the result of it had turned out; but I soon after found that I had been too hasty in my com- munication. Sir Charles, in his answer to my letter, expressed doubts respecting the fact; but, before his letter had reached me, I had learned from my own expe- rience, how very dangerous it is, in philosophical investigations, to draw conclusions from single experiments. Having removed the balance, with the 2 bottles attached to it, from the cold into the warm room, which still remained at the temperature of 6*1°, the ice in the bottle a gradually thawed; and, being at length totally reduced to water, and this water having acquired the temperature of the surrounding air, the 2 bottles, after being wiped perfectly clean and dry, were found to weigh as at the beginning of the experiment, before the water was frozen. This experiment being repeated, gave nearly the same result, the water appearing, when frozen, to be heavier than in VOL. XVIII. 3 S 498 PHILOSOPHICAL TRANSACTIONS. [ANNO 17 QQ. its fluid state; but some irregularity in the manner in which the water lost the additional weight which it had appeared to acquire on being frozen, when it was afterwards thawed, as also a sensible difference in the quantities of weight appa- rently acquired in the different experiments, led me to suspect, that the experiment could not be depended on for deciding the fact in question ; I therefore repeated it, with some variations and improvements; but, before I give an account of my fur- ther investigations relative to this subject, it may not be amiss to mention the me- thod I pursued for discovering whether the appearances mentioned in the foregoing experiments might not arise from the imperfections of my balance; and it may likewise be proper to give an account, in this place, of an intermediate experiment which I made, with a view to discover, by a shorter route, and in a manner less exceptionable than that above-mentioned, whether bodies actually lose, or acquire, any weight, on acquiring an additional quantity of latent heat. My suspicions respecting the accuracy of the balance arose from a knowledge, which I acquired from the maker of it, of the manner in which it was constructed. The 3 principal points of the balance having been determined, as nearly as possible, by measurement, the axes of motion were firmly fixed in their places, in a right line, and the beam being afterwards finished, and its 2 arms brought to be in equi- librio, the balance was proved by suspending weights, which before were known to be exactly equal, to the ends of its arms. If with these weights the balance re- mained in equilibrio, it was considered as a proof that the beam was just; but if one arm was found to preponderate, the other was gradually lengthened, by beating it on an anvil, till the difference of the lengths of the arms was reduced to nothing, or till equal weights, suspended to the 2 arms, remained in equilibrio; care being taken before each trial to bring the 2 ends of the beam to be in equilibrio, by reducing, with the file, the arm which had been lengthened. Though, in this method of constructing balances, the most perfect equality in the lengths of the arms may be obtained, and consequently the greatest possible accuracy, when used at a time when the temperature of the air is the same as when the balance was made, yet as it may happen, that in order to bring the arms of the balance to be of the same length, one of them may be much more hammered than the other, I suspected it might be possible that the texture of the metal forming the 2 arms might be rendered so far different, by this operation, as to occasion a differ- ence in their expansions with heat; and that this difference might occasion a sen- sible error in the balance when, being charged with a great weight, it should be exposed to a considerable change of temperature. To determine whether the apparent augmentation of weight, in the experiments above related, arose in any degree from this cause, I had only to repeat the experi- ment, causing the 2 bottles a and b to change places on the arms of the balance; but as I had already found a sensible difference in the results of different repetitions of the same experiment, made as nearly as possible under the same circumstances, and as it was above all things of importance to ascertain the accuracy of my balance, VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 499 I preferred making a particular experiment for that purpose. My first idea was, to suspend to the arms of the balance, by very fine wires, 2 equal globes of glass, filled with mercury, and, suffering them to remain in my room till they should have acquired the known temperature of the air in it, to have removed them after- ward into the cold, and to have seen if they still remained in equilibrio, under such difference of temperature; but, considering the obstinacy with which moisture ad- heres to the surface of glass, and being afraid that, somehow or other, notwith- standing all my precautions, one of the globes might acquire or retain more of it than the other, and that by that means its apparent weight might be increased; and having found by a former experiment, of which I have already had the honour of communicating an account to the r. s., that the gilt surfaces of metals do not at- tract moisture; instead of the glass globes filled with mercury, I made use of 2 equal solid globes of brass, well gilt and burnished, which I suspended to the arms of the balance, by fine gold wires. These globes, which weighed 4975 grains each, being wiped perfectly clean, and having acquired the temperature (6l°) Of my room, in which they were exposed more than '24 hours, were brought into the most scrupulous equilibrium, and were then removed, attached to the arms of the balance, into a room in which the air was at the temperature of 2(3°, where they were left all night. The result of this trial furnished the most satisfactory proof of the accuracy of the balance; for, on entering the room, I found the equilibrium as perfect as at the beginning of the experiment. Having thus removed my doubts respecting the accuracy of my ba- lance, I now resumed my investigations relative to the augmentation of weight which fluids have been said to acquire on being congealed. In the experiments which I had made, I had, as I then imagined, guarded as much as possible against every source of error and deception. The bottles being of the same size, neither any occasional alteration in the pressure of the atmosphere during the experiment, nor the necessary and unavoidable difference in the den- sities of the air in the hot and in the cold rooms in which they were weighed, could affect their apparent weights; and their shapes and their quantities of surface being the same, and as they remained for such a considerable length of time in the heat and cold to which they were exposed, I flattered myself that the quantities of mois- ture remaining attached to their surfaces, could not be so different as sensibly to affect the results of the experiments. But, in regard to this last circumstance, I afterwards found reason to conclude that my opinion was erroneous. Admitting the fact stated by Dr. Fordyce, and which my experiments had hitherto rather tended to corroborate than to contradict, I could not conceive any other cause for the augmentation of the apparent weight of water, on its being frozen, than the loss of so great a proportion of its latent heat as that fluid is known to evolve when it congeals ; and I concluded, that if the loss of latent heat added to the weight of one body, it must of necessity produce the same effect on another, and consequently, that the augmentation of the quantity of latent heat must, in 3 s 2 500 PHILOSOPHICAL TRANSACTIONS. [ANNO 1 7QQ. all bodies, and in all cases, diminish their apparent weights. To determine whether this is actually the case or not, I made the following experiment. Having provided 2 bottles, as nearly alike as possible, and in all respects similar to those made use of in the experiments above-mentioned, into one of them I put 4012.46 grains of water, and into the other an equal weight of mercury; and, sealing them herme- tically, and suspending them to the arms of the balance, I suffered them to acquire the temperature of my room, Gl°; then, bringing them into a perfect equilibrium with each other, I removed them into a room in which the air was at the tempera- ture of 34°, where they remained 24 hours. But there was not the least appear- ance of either of them acquiring, or losing, any weight. Here it is very certain, that the quantity of heat lost by the water, must have been very considerably greater than that lost by the mercury; the specific quantities of latent heat in water and in mercury, having been determined to be to each other as 1000 to 33; but this difference in the quantities of heat lost, produced no sen- sible difference on the weights of the fluids in question. Had any difference of weight really existed, had it been no more than one millionth part of the weight of either of the fluids, I should certainly have discovered it; and had it amounted to so much as frrlWr Part of that weight, I should have been able to have measured it; so sensible, and so very accurate, is the balance which I used in these experiments. I was now much confirmed in my suspicions, that the apparent augmentation of the weight of the water on its being frozen, in the experiments before related, arose from some accidental cause; but I was not able to conceive what that cause could possibly be, — unless it were, either a greater quantity of moisture attached to the external surface of the bottle which contained the water, than to the surface of that containing the spirits of wine, — or some vertical current or currents of air, caused by the bottles, or one of them not being exactly of the temperature of the surrounding atmosphere. Though I had foreseen, and, as I thought, guarded suf- ficiently against these accidents, by making use of bottles of the same size and form, and which were blown of the same kind of glass, and at the same time; and by suffering the bottles, in the experiments, to remain for so considerable a length of time exposed to the different degrees of heat and of cold, which alter- nately they were made to acquire; yet, as I did not know the relative conducting powers of ice and of spirit of wine with respect to heat; or, in other words, the degrees of facility or difficulty with which they acquire the temperature of the me- dium in which they are exposed; or the time taken up in that operation; and con- sequently was not absolutely certain as to the equality of the temperatures of the contents of the bottles at the time when their weights were compared, I determined now to repeat the experiments, with such variations as should put the matter in question out of all doubt. I was the more anxious to assure myself of the real temperatures of the bottles and of their contents, as any difference in their tem- peratures might vitiate the experiment, not only by causing unequal currents in the VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 50] air, but also by causing, at the same time, a greater or less quantity of moisture to remain attached to the glass. To remedy these evils, and also to render the experiment more striking and satis- factory in other respects, I proceeded in the following manner. Having provided 3 bottles a, b, and c, as nearly alike as possible, and resembling in all respects those already described; into the first, A, I put 4214.28 grains of water, and a small thermometer, made on purpose for the experiment, and suspended in the bottle in such a manner that its bulb remained in the middle of the mass of water; into the 2d bottle, b, I put a like weight of spirit of wine, with a like thermometer; and into the bottle c I put an equal weight of mercury. These bottles, being all hermetically sealed, were placed in a large room, in a corner far removed from the doors and windows, and where the air appeared to be perfectly quiet; and being suffered to remain in this situation more than 24 hours, the heat of the room (6l°) being kept up all that time with as little variation as possible, and the contents of the bottles a and b appearing, by their inclosed thermometers, to be exactly at the same temperature, the bottles were all wiped with a very clean dry cambric hand- kerchief; and being afterwards suffered to remain exposed to the free air of the room a couple of hours longer, in order that any inequalities in the quantities of heat, or of the moisture attached to their surfaces, which might have been occasioned by the wiping, might be corrected by the operation of the atmosphere by which they were surrounded, they were all weighed, and were brought into the most ex- act equilibrium with each other, by means of small pieces of very fine silver wire, attached to the necks of those of the bottles which were the lightest. This being done, the bottles were all removed into a room in which the air was at 30°, where they were suffered to remain, perfectly at rest and undisturbed, 48 hours; the bottles a and b being suspended to the arms of the balance, and the bottle c suspended, at an equal height, to the arm of a stand constructed for that purpose, and placed as near the balance as possible, and a very sensible thermometer suspended by the side of it. At the end of 48 hours, during which time the appa- ratus was left in this situation, I entered the room, opening the door very gently, for fear of disturbing the balance; when I had the pleasure to find the 3 thermo- meters, viz. that in the bottle a, which was now inclosed in a solid cake of ice, that in the bottle b, and that suspended in the open air of the room, all standing at the same point, 29° f, and the bottles a and b remaining in the most perfect equilibrium. To assure myself that the play of the balance was free, I now ap- proached it very gently, and caused it to vibrate; and I had the satisfaction to find, not only that it moved with the utmost freedom, but also, when its vibration ceased that it rested precisely at the point from which it had set out. I now removed the bottle b from the balance, and put the bottle c in its place; and I found that that likewise remained of the same apparent weight as at the be- ginning of the experiment, being in the same perfect equilibrium with the bottle A as at first* I afterwards removed the whole apparatus into a warm room, and 502 PHILOSOPHICAL TRANSACTIONS. [ANNO \7QQ. causing the ice in the bottle a to thaw, and suffering the 3 bottles to remain till they and their contents had acquired the exact temperature of the surrounding air, I wiped them very clean, and comparing them together, I found their weights remained unaltered. This experiment I afterwards repeated several times, and al- ways with precisely the same result; the water, in no instance, appearing to gain, or to lose, the least weight, on being frozen, or on being thawed; neither were the relative weights of the fluids in either of the other bottles in the least changed, by the various degrees of heat, and of cold, to which they were exposed. If the bottle were weighed at a time when their contents were not precisely of the same temperature, they would frequently appear to have gained, or to have lost, some- thing of their weights; — but this doubtless arose from the vertical currents which they caused in the atmosphere, on being heated or cooled in it; or to unequal quantities of moisture attached to the surfaces of the bottles; — or to both these causes operating together. As I knew that the conducting power of mercury, with respect to heat, was considerably greater than either that of water, or that of spirit of wine, while its capacity for receiving heat is much less than that of either of them, I did not think it necessary to inclose a thermometer in the bottle c, which contained the mercury; for it was evident, that when the contents of the two other bottles should appear, by their thermometers, to have arrived at the temperature of the medium in which they were exposed, the contents of the bottle c could not fail to have acquired it also, and even to have arrived at it before them; for the time taken up in the heating or in the cooling of any body is, caeteris paribus, as the capacity of the body to receive and retain heat directly, and as its conducting power inversely. The bottles were suspended to the balance by silver wires, about 1 inches long, with hooks at the ends of them ; and, in removing and changing the bottles, I took care not to touch the glass. I likewise avoided on all occasions, and particu- larly in the cold room, coming near the balance with my breath, or touching it, or any part of the apparatus, with my naked hands. Having determined that water does not acquire or lose any weight, on being changed from a state of fluidity to that of ice, and vice versa, I shall now take my final leave of a subject which has long occupied me, and which has cost me much pains and trouble; being fully convinced, from the results of the above-mentioned experiments, that if heat be in fact a substance, or matter, — a fluid sui generis, as has been supposed, — which, passing from one body to another, and being accumu- lated, is the immediate cause of the phenomena we observe in heated bodies, (of which, however, I cannot help entertaining doubts), it must be something so infi- nitely rare, even in its most condensed state, as to baffle all our attempts to discover its gravity. And if the opinion which has been adopted by many of our ablest philosophers, that heat is nothing more than an intestine vibratory motion of the constituent parts of heated bodies, should be well founded, it is clear that the weights of bodies can in no wise be affected by such motion. It is, no doubt, on VOL. LXXXIX.] PHILOSOPHICAL TKANSACTIONS. 503 the supposition that heat is a substance distinct from the heated body, and which is accumulated in it, that all the experiments which have been undertaken, with a view to determine the weight which bodies have been supposed to gain, or to lose, on being heated or cooled, have been made ; and on this supposition, but without however adopting it entirely, as I do not conceive it to be sufficiently proved, all my researches have been directed. The experiments with water, and with ice, were made in a manner which I take to be perfectly unexceptionable; — in which no foreign cause whatever could affect the results of them; — and the quantity of heat which water is known to part with, on being frozen, is so considerable, that if this loss has no effect on its apparent weight, it may be presumed that we shall never be able to contrive an experiment by which we render the weight of heat sensible. Water, on being frozen, has been found to lose a quantity of heat amounting to 140 degrees of Fahrenheit's thermometer; or, which is the same thing, the heat which a given quantity of water, previously cooled to the temperature of freezing, actually loses, on being changed to ice, if it were to be imbibed and retained by an equal quantity of water, at the given temperature, that of freezing, would heat iM40 degrees, or would raise it to the temperature of (32° + 140) 1 62° of Fahrenheit's thermometer, which is only 6o° short of that of boiling water; consequently, any given quantity of water, at the temperature of freezing, on being actually frozen, loses almost as much heat as, added to it, would be sufficient to make it boil. It is clear, therefore, that the difference in the quantities of heat contained by the water in its fluid state, and heated to the temperature of 6*1° p, and by the ice, in the experiments before mentioned, was at least nearly equal to that between water in a state of boiling, and the same at the temperature of freezing. But this quantity of heat will appear much more considerable, when we con- sider the great capacity of water to contain heat, and the great apparent effect which the heat that water loses on being frozen would produce, were to be imbibed by, or communicated to any body whose power of receiving and retaining heat is much less. The capacity of water to receive and retain heat, — or what has been called its specific quantity of latent heat, — has been found to be that of gold as 1000 to 50, — or as 20 to 1 ; consequently, the heat which any given quantity of water loses on being frozen, — were it to be communicated to an equal weight of gold, at the temperature of freezing, the gold, instead of being heated 1(52°, would be heated 140 X 20 = 2800°, or would be raised to a bright red heat. It appears therefore to be clearly proved, by my experiments, that a quantity of heat equal to that which 4214 grs., or about 94- oz. of gold, would require to heat it from the temperature of freezing water to be red-hot, has no sensible effect on a balance capable of indicating so small a variation of weight as that of t ooo-tnnr Part of the body in question ; and if the weight of gold is neither augmented nor lessened by one millionth part, on being heated from the point of freezing water to that of a 504 PHILOSOPHICAL TRANSACTIONS. [ANNO 17QQ. bright red heat, I think we may very safely conclude, that all attempts to discover any effect of heat on the apparent weights of bodies, will be fruitless. XII. Experiments on the Fecundation of Vegetables. By Thomas Andrew Knight, Esq. p. 195. In this paper Mr. K. gives an account of some experiments on plants, which prove the existence of super-foetation in the vegetable world, and which seem likely to conduce to improvements in agriculture. The breeders of animals, (says Mr. K.,) have very long entertained an opinion that considerable advantages are obtained by breeding from males and females not related to each other. Though this opinion has lately been controverted, the number of its opposers has gradually diminished; and I can speak from my own observation and experience, that animals degenerate, in size at least, on the same pasture, and in other respects under the same management, when this process of crossing the breed is neglected. The close analogy between the animal and vege- table world, and the sexual system equally pervading both, induced me to suppose, that similar means might be productive of similar effects in each; and the event has, I think, fully justified this opinion. The principal object I had in view, was to obtain new and improved varieties of the apple, to supply the place of those which have become diseased and unproductive, by having been cultivated beyond the period which nature appears to have assigned to their existence. But, as I foresaw that several years must elapse, before the success or failure of this process could possibly be ascertained, I wished, in the interval, to see what would be its effects on annual plants. Among these, none appeared so well calculated to answer my pur- pose as the common pea; not only because I could obtain many varieties of this plant, of different forms, sizes, and colours; but also, because the structure of its blossom, by preventing the ingress of insects and adventitious farina, has rendered its varieties remarkably permanent. I had a kind growing in my garden, which, having been long cultivated in the same soil, had ceased to be productive, and did not appear to recover the whole of its former vigour, when removed to a soil of a somewhat different quality; on this, my first experiment, in 1787, was made. Having opened a dozen of its immature blossoms, I destroyed the male parts, taking great care not to injure the female ones; and, a few days afterwards, when the blossoms appeared mature, I introduced the farina of a very large and luxuriant grey pea into one half of the blossoms, leaving the other half as they were. The pods of each grew equally well; but I soon perceived, that in those into whose blossoms the farina had not been introduced, the seeds remained nearly as they were before the blossoms expanded, and in that state they withered. Those in the other pods attained maturity, but were not in any sensible degree different from those afforded by other plants of the same variety; owing, I imagine, to the ex- ternal covering of the seed, as I have found in other plants, being furnished en- TOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 505 tirely by the female. In the succeeding spring, however, the difference became extremely obvious; for the plants from them rose with excessive luxuriance, and the colour of their leaves and stems clearly indicated, that they had all exchanged their whiteness for the colour of the male parent : the seeds produced in autumn were dark gray. By introducing the farina of another white variety, or in some instances by simple culture, I found this colour was easily discharged, and a nume- rous variety of new kinds produced, many of which were, in size, and in every other respect, much superior to the original white kind, and grew with excessive luxuriance, some of them attaining the height of more than 12 feet. I had frequent occasion to observe, in this plant, a stronger tendency to produce purple blossoms and coloured seeds, than white ones ; for when I introduced the farina of a purple blossom into a white one, the whole of the seeds in the succeeding year became coloured ; but when I endeavoured to discharge this colour, by reversing the pro- cess, a part only of them afforded plants with white blossoms; this part sometimes occupying one end of the pod, and being at other times irregularly intermixed with those which, when sown, retained their colour. It may perhaps be supposed, that something might depend on the quantity of farina employed; but I never could discover in this, or in any other experiment in which super fee tation did not take place, that the largest or smallest quantity of farina afforded any difference in the effect produced. The dissimilarity I observed in the offspring afforded by different kinds of farina, m these experiments, pointed out an easy method of ascertaining whether super- foetation, the existence of which has been admitted among animals, could also take place in the vegetable world. For, as the offspring of a white pea is always white, unless the farina of a coloured kind be introduced into the blossom, and as the colour of the gray one is always transferred to its offspring, though the female be white, it readily occurred, that if the farina of both were mingled, or applied at the same moment, the offspring of each could be easily distinguished. My first experiment was not altogether successful; for the offspring of 5 pods, the whole which escaped the birds, received their colour from the coloured male. There was however a strong resemblance to the other male, in the growth and character of more than one of the plants; and the seeds of several, in the autumn, very closely resembled it in every thing but colour. In this experiment, I used the farina of a white pea, which possessed the. remarkable property of shrivelling excessively when ripe; and in the 2d year I obtained white seeds, from the gray ones above-men- tioned, perfectly similar to it. I am strongly disposed to believe, that the seeds were here of common parentage; but I do not conceive myself to be in possession of facts sufficient to enable me to speak with decision on this question. If however the female afford the first organized atom, and the farina act only as a stimulus, it appears by no means impossible, that the explosion of 2 vesicles of farina, at the same moment, taken from different plants, may afford seeds, as I have supposed, vol. xvni. 3 T 506 PHILOSOPHICAL TRANSACTIONS. [ANNO \7QQ. of common parentage; and, as I am unable to discover any source of inaccuracy in this experiment, I must believe this to have happened. Another species of superfcetation, if I have justly applied that term to a process in which 1 seed appears to have been the offspring of 2 males, has occurred to me so often, as to remove all possibility of doubt as to its existence. In 1797, the year after I had seen the result of the last-mentioned experiment, having prepared a great many white blossoms, I introduced the farina of a white and that of a gray pea, nearly at the same moment, into each ; and as, in the last year the character of the coloured male had prevailed, I used its farina more sparingly than that of the white one; and now almost every pod afforded plants of different colours. The majority however were white; but the characters of the 2 kinds were not sufficiently distinct to allow me to judge with precision, whether any of the seeds produced were of common parentage or not. In the last year, I was more fortunate: having prepared blossoms of the little early frame pea, I introduced its own farina, and immediately afterwards that of a very large and late gray kind, and I sowed the seeds thus obtained in the end of the last summer. Many of them retained the colour and character of the small early pea, not in the slightest degree altered, and blossomed before they were 18 inches high; while others, taken from the same pods, whose colour was changed, grew to the height of more than 4 feet, and were killed by the frost, before any blossoms appeared. It is evident, that in the&e instances superfcetation took place; and it is equally evident, that the seeds were not all of common parentage. Should subsequent experience evince, that a single plant may be the offspring of 2 males, the analogy between animal and vegetable nature may induce some curious conjecture, relative to the process of generation in the animal world. In the course of the preceding experiments, I could never observe that the cha- racter, either of the male or female, in this plant, at all preponderated in the offspring; but, as this point appeared interesting, I made a few trials to ascertain it. And, as the foregoing observations had occurred in experiments made principally to obtain new and improved varieties of the pea, for garden culture, I chose, for a similar purpose, the more hardy varieties usually sown in the fields. By introducing the farina of the largest and most luxuriant kinds into the blossoms of the most dimi- nutive, and by reversing this process, I found that the powers of the male and female, in their effects on the offspring, are exactly equal. The vigour of the growth, the size of the seeds produced, and the season of maturity, were the same, though the one was a very early, and the other a late variety. I had, in this experiment, a striking instance of the stimulative effects of crossing the breeds; for the smallest variety, whose height rarely exceeded 2 feet, was increased to 6 feet; while the height of the large and luxuriant kind was very little diminished. By this process it is evident, that any number of new varieties may be obtained; and it is highly probable, that many of these will be found better calculated to cor- >0L. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 507 rect the defects of different soils arid situations, than any we have at present; for I imagine that all we now possess, have in a great measure been the produce of acci- dent; and it will rarely happen, in this or any other case, that accident has done all that art will be found able to accomplish. The success of my endeavours to produce improved varieties of the pea, induced me to try some experiments on wheat; but these did not succeed to my expecta- tions. I readily obtained as many varieties as I wished, by merely sowing the dif- ferent kinds together; for the structure of the blossom of this plant, unlike that of the pea, freely admits the ingress of adventitious farina, and is thence very liable to sport in varieties. Some of those I obtained very excellent; others very bad; and none of them permanent. By separating the best varieties, a most abundant crop was produced ; but its quality was not quite equal to the quantity, and all the discarded varieties again made their appearance. It appeared to be an extraordinary circumstance, that in the years 1795 and 1796, when almost the whole crop of corn in the island was blighted, the varieties thus obtained, and these only, escaped, in this neighbourhood, though sown in several different soils and situations. My success on the apple, as far as long experience and attention have enabled me to judge from the cultivated appearance of trees which have not yet borne fruit, has been fully equal to my hopes. But, as the improvement of the fruit was the first object of my attention, no probable means of improvement, either from soil or aspect, were neglected. The plants however which I obtained from my efforts to unite the good qualities of 2 kinds of apple, seem to possess the greatest health and luxuriance of growth, as well as the most promising appearance in other respects. In some of these, the character of the male appears to prevail; in others, that of the female; and in others, both appear blended, or neither is distinguishable. These variations, which were often observable in the seeds taken from a single apple, evidently arise from the want of permanence in the character of this fruit, when raised from seed. The results of similar experiments on another fruit, the grape, were nearly the same as of those on the apple, except that, by mingling the farina of a black and a white grape, just as the blossoms of the latter were expanding, I sometimes ob- tained plants, from the same berry, so dissimilar, that I had good reason to believe them the produce of superfcetation. By taking off the cups, and destroying the immature male parts, as in the pea, I perfectly succeeded in combining the cha- racters of different varieties of this fruit, as far as the changes of form and autumnal tints, in the leaves of the offspring, will allow me to judge. Many experiments, of the same kind, were tried on other plants ; but it is suffi- cient to say that all tended to evince, that improved varieties of every fruit and esculent plant may be obtained by this process, and that nature intended that a sexual intercourse should take place between neighbouring plants of the same spe- cies. The probability of this will I think be apparent, when we take a view of the variety of methods which nature has taken to disperse the farina, even of those 3 t 3 508 PHILOSOPHICAL TRANSACTIONS. [ANNO 1790. plants in which it has placed the male and female parts within the same empalement. It is often scattered by an elastic exertion of the filaments which support it, on the first opening of the blossom ; and its excessive lightness renders it capable of being carried to a great distance by the wind. Its position within the blossom, is gene- rally well adapted to place it on the bodies of insects; and the villous coat of the numerous family of bees is not less well calculated to carry it. I have frequently observed, with great pleasure, the dispersion of the farina of some of the grasses, when the sun had just risen in a dewy morning. It seemed to be impelled from the plant with considerable force; and, being blue, was easily visible, and very strongly resembled, in appearance, the explosion of a grain of gunpowder. An examination of the structure of the blossoms of many plants, will immediately point out, that nature has something more in view, than that its own proper males should fecundate each blossom ; for the means it employs are always those best calculated to answer the intended purpose. But the farina is often so placed, that it can never reach the summit of the pointal, unless by adventitious means; and many trials have convinced me that it has no action on any other part of it. In promoting this sexual intercourse between neighbouring plants of the same species, nature appears to have an important purpose in view; for, independent of its stimu- lative power, this intercourse certainly tends to confine within more narrow limits, those variations which accidental richness or poverty of soil usually produces. It may be objected, by those who admit the existence of vegetable mules, that, under this extensive intercourse, these must have been more numerous; but my total want of success, in many endeavours, to produce a single mule plant, makes me much disposed to believe that hybrid plants have been mistaken for mules; and to doubt, with all the deference I feel for the opinions of Linnaeus and his illustrious followers, whether nature ever did, or ever will, permit the production of such a monster. The existence of numerous mules in the animal world, between kindred species, is allowed; but nature has here guarded against their production, by im- pelling every animal to seek its proper mate; and among the feathered tribe, when, from perversion of appetite, sexual intercourse takes place between those of distinct genera,* it has, in some instances at least, rendered the death of the female the inevitable consequence. But in the vegetable world there is not any thing to direct the male to its proper female: its farina is carried, by winds and insects, to plants of every different genus and species ; and it therefore appears to me, as vegetable mules certainly are not common, that nature has not permitted them to exist at all. I cannot dismiss this subject, without expressing my regret, that those who have made the science of botany their study, should have considered the improvement of those vegetables which, in their cultivated state, afford the largest portion of subsistence to mankind and other animals, as little connected , with the object of their pursuit. Hence it has happened, that while much attention has been paid to * This is said to be the case with the drake and the hen.— Orig. VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 509 the improvement of every species of useful animal, the most valuable esculent plants have been almost wholly neglected. But when the extent of the benefit which would arise to the agriculture of the country, from the possession of varieties of plants which, with the same extent of soil and labour, would afford even a small increase of produce, is considered, this subject appears of no inconsiderable im- portance. The improvement of animals is attended with much expence, and the improved kinds necessarily extend themselves slowly; but a single bushel of im- proved wheat or peas, may in J O years be made to afford seed enough to supply the whole island; and a single apple, or other fruit-tree, may within the same time be extended to every garden in it. These considerations have given rise to the fore- going observations; for it was much my wish to have ascertained first, whether in any instance a single plant can be the offspring of 2 male parents. The decision of that question must of necessity have occupied 2 years, and must therefore be left to the test of future experiment. XIII. Observations on the Different Species of Asiatic Elephants, and their Mode of Dentition. By John Corse, Esq. p. 205. Before entering on this new and curious subject, it may be proper to premise a few general observations on the various zats, or casts, of the Asiatic elephant, and on the tusks ; as the form and size of these give a diversity of appearance, which may be considered as forming varieties of the same species of elephant. Both males and females are divided into 2 casts, by the natives of Bengal, viz. the koomareah* and the merghee *|~; and this without any regard to the appearance, shape, or size of the tusks in the male, as these serve merely to characterize some varieties in the species. The koomareah is a deep-bodied, strong, compact ele- phant, with a large trunk, legs short, but thick, in proportion to the size of the animal. The merghee cast, when full grown, is generally taller than the former, but has not so compact a form, nor is he so strong, or so capable of bearing fatigue; his legs are long, he travels fast, has a lighter body, and his trunk is both short and slender, in proportion to his height. A large trunk is always esteemed a great beauty in an elephant; so that the koomareah is preferred, not only for this, but for its superior strength, by which it can undergo greater fatigue, and carry heavier loads, than the merghee. As there appears however no predilection in any of these elephants to have con- nection with his own particular kind, from an indiscriminate intercourse several varieties are produced, partaking of the qualities of their respective progenitors. This mixed breed is in greater or less estimation, in proportion as it partakes of the qualities of the koomareah, or merghee cast. A breed from a pure koomareah * Koomareah signifies of a princely race; being derived from koomarah, a prince, or king's son. — t Merghee, properly mrigee, from mrigah, a deer, or hunting, signifies an elephant used in hunting j or it is so called from its slender make. — Orig. 510 PHILOSOPHICAL TRANSACTIONS. [ANNO IfQQ. and merghee is termed sunkareah*, or mergha-bauliah-j~; but a further mixture or crossing of the breed renders it extremely difficult for the hunters to ascertain the variety. Besides the koomareah, merghee, and sunkareah breeds, several varieties are generally to be found in the same herd; but the nearer an elephant approaches to the true koomareah species, the more he is preferred, especially by the natives, and the higher price he will consequently bear. Europeans are not so particular, and will sometimes prefer a merghee female for hunting and riding on, when she is known to have remarkably good paces, and to be of a mild and tract- able disposition. The elephants for the service of the Hon. East India Company, are generally taken in the province of Chittigong and Tiperah ; but, from what I have heard, those to the southward of Chittigong, in the Burmagh territories and kingdom of Pegu, are of a superior breed. In confirmation of this opinion, I may observe, that the elephants taken to the south of the Goomty river, which divides the province of Tiperah from east to west, are generally better than those taken to the north of that river; and though elephants are taken at Pilibet, as far north as latitude 29°, in the Vizier of Oude's territories, yet the Vizier, and the officers of his court, give those taken in Chittigong and Tiperah a decided preference, being much larger and stronger than the Pilibet elephant, Till the year 1790, Tiperah was a part of the Chittigong province; and so sensible was the Bengal government of the superiority of the southern elephants, for carrying burdens, enduring fatigue, and being less liable to casualties, that in the late contracts for supplying the army with those useful animals, the contractor was bound not to send any elephant to the military stations, taken north of the Chittigong province. Hence we may conclude the torrid zone to be the natural clime, and the most favourable for producing the largest, the best, and the hardiest elephant; and that when this animal migrates beyond the tropics, the species degenerates. On the coast of Malabar, elephants are taken as far north as the territories of the Coorgah Rajah; but these are much inferior to the Ceylon elephant, and, from this circum- stance, the report of the superiority of the Ceylon elephant to all others has pro- bably originated. Most of the accounts we have had respecting the Asiatic elephant, have been given by gentlemen who resided many years ago on the coast of Malabar or Coromandel; where, at that time, they had but few opportunities of seeing the Chittigong or Pegu elephant. After premising these general observations, I may here observe, that elephants have 2 tusks, in the upper jaw only; but those in some of the females are so small as not to appear beyond the lip, while in others they are almost as large as in one variety of the male, named mooknahj. Elephants have no incisores or cutting * Sunkareah signifies a mixed breed, from sunkarah, a mixture. + Mergha-bauliah signifies for the most part merghee; that is, partaking more of their cast than of the koomareah. J Probably from mookh, the mouth or face. — Orig. YOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 511 teeth; and the grinders are so much alike in males and females, that one description will serve for both. The largest tusks, from which the best ivory is supplied, are, taken from that species of male named dauntelah*, in consequence of his large tusks, and whose countenance, from this circumstance, is the most opposite in appearance, to that of the mooknah; which, as before observed, is hardly to be distinguished, by his head, from a female elephant. Though there is a material difference in the appearance of a mooknah and a dauntelah, as well as in the value of the tusks, yet, if they are of the same cast, size, and disposition, and perfect, that is, free from any defect or blemish, there is scarcely any difference in their price. An elephant is said to be perfect, when his ears are large and rounded, not ragged, or indented at the margin; his eyes of a dark hazle colour, free from specks; the roof of his mouth, and his tongue, without dark or black spots of any consider- able size; his trunk large, and his tail long, with a tuft of hair reaching nearly to the ground. There must be 5 nails on each of his fore-feet, and 4 on each of the hind ones; his head well set on, and carried rather high. The arch or curve of his back rising gradually from the shoulder to the middle, and thence descend- ing to the insertion of the tail; and all his joints firm and strong. There are several other points, of less consequence, which are noticed by the natives as well as Europeans. The dauntelah is generally more daring, and less manageable, than the mooknah ; for this reason, till the temper and disposition of the two species are ascertained, Europeans will prefer the mooknah; but the natives, who are fond of show, generally take their chance, and prefer the dauntelah; which, when known to be of a mild and gentle disposition, will always be preferred, both by Europeans and natives. The varieties between the mooknah and dauntelah are considerable, and for these there are appropriate names, according as the form of the tusks varies from the projecting horizontal, but rather elevated, curve of the pullung daunt -f~ of the perfect dauntelah, to the nearly straight tusks of the mooknah, which point directly downwards. When a dauntelah has never had but 1 tusk, and this of the pullung sort, he is said to be a goneish or ganesa J, and will sell to the Hindoo princes for a very high price, to be kept in state, and worshipped as a divinity. I have seen elephants apparently of this kind; but when accurately examined, the tusk wanting appeared to me to have been lost by accident, so that I cannot say I ever saw a male which had originally only 1 tusk. A 2d variety of the dauntelah is, when the large tusks point downwards, pro- jecting only a little way beyond the trunk; he is then said to have soor or choor * Dauntelah signifies toothy ; having large or fine teeth. f Pullung signifies a bed or cot, and daunt, teeth ; and, from the tusks projecting so regularly, and being a little curved and elevated at the extremities, the natives suppose a man might he on them at his ease, as on a bed \ Ganesa is the name of the Hindoo god of wisdom, who is represented witii a head like an elephant's, with only 1 tooth. See Asiatic Researches, vol. 1, art. On the Gods of Greece, Italy, and India. — Orig. 512 PHILOSOPHICAL TRANSACTIONS. [aNNO1790; daunt*. A 3d variety is the puttel-dauntee, whose tusks are straight, like those of the mooknah, only much longer, and thicker. A 4th variety is the ankoos- dauntee-J-, where 1 tusk grows nearly horizontal, like the pulling-daunt, and the other like the puttel-daunt. Besides these, the elephant-keepers notice other varieties, which are less distinct. All these tusks, in the male, are fixed very deep in the upper jaw; and the root or upper part, which is hollow and filled with a core, goes as high as the insertion of the trunk, round the margin of the nasal opening to the throat; which opening is just below the protuberance of the forehead. Through this opening the elephant breathes, and by its means he sucks up water into his trunk; between it and the roots of the tusks there is only a thin bony plate. The first or milk tusks of an elephant never grow to any size, but are shed between the 1 st and 2d year, when not 2 inches in length. These, as well as the first grinders, are named by the natives dood-kau-daunt, which literally sig- nifies milk teeth. The tusks which are shed have a considerable part of the root or fang absorbed before this happens. The time at which the tusks cut the gum, varies considerably. I have known a young one get his tusks when about 5 months old; whereas the tusks of another did not cut the gum till he was 7 months old. Those tusks which are deciduous are perfect, and without any hollow in the root, in a fcetus which is come to its full time; at this period, the socket of the perma- nent tusk begins to be formed, on the inner side of the deciduous tusk. A young elephant had shed 1 of his milk tusks on the 6th of Nov. 1790, when near 13 months old, and the other on the 27th of Dec, when above 14 months old: they were merely 2 black-coloured stumps, when shed; but 2 months afterwards the permanent ones cut the gum, and on the 19th of April, 1791, they were 1 inch long, but black and ragged at the ends. When they became longer, and projected beyond the lip, they soon were worn smooth, by the motion and friction of the trunk. Another young elephant did not shed his milk tusks till he was 16 months old; which proves that there is considerable variety in the time at which this happens. The permanent tusks of the female are very small, in comparison with those of the male, and do not take their rise so deep in the jaw; but they use them as weapons of offence, in the same manner as the male named mooknah, that is, by putting their head above another elephant, and pressing their tusks down into the animal. These tusks are never shed, and sometimes grow to a very large size in the male. The largest I have known in Bengal, did not exceed 72 lb. avoirdupois: at Tiperah, they seldom exceed 50 lb.; but both these weights are very inferior to that of the tusks brought from other places to the India House, where I have seen some near 150 lb. each. From what part of Asia they came, I * Soor or choor-daunt signifies hogs' teeth j from the tusks having some distant resemblance to those in the lower jaw of the hog. t Ankoos signifies a crook, and is particularly applied to the weapon the drivers use to govern the elephant, to which these irregular tusks bear some resemblance. — Orig. TOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 513 could not learn, but suspect they were imported from Pegu to Calcutta, and thence to London. The African elephant is said to be smaller than the Asiatic; yet I am credibly informed, by the ivory dealers in London, that the largest tusks generally come from Africa, and are of a better texture, and less liable to turn yellow, than the Indian ivory, after being manufactured. This probably is owing to the tusks having laid longer in Africa, before they were imported, than those brought from Asia. In the latter country, most of the tusks exported are taken from elephants immediately after their death ; whereas the Africans find many teeth in the desert places which have been frequented by this animal. The intense heat of a vertical sun will undoubtedly render the ivory firmer and harder, if the tusks happen to lie on the scorching sand, or in any other dry situation. The increase of the tusk arises from circular layers of ivory, applied internally, from the core on which they are formed, similar to what happens in the growth of the horns of some animals. When the tusks of the living elephant are sawn through, and the remaining portion exposed some months to the air, this structure is clearly shown. If the jteriod in which one of these circular layers is completed could be ascertained, this might lead us to fix, with tolerable precision, the age of an elephant, by counting the circles in each tusk. Cutting off a portion of the tusks of a living elephant is a common practice; it is done with a view to make the tusks grow thicker, when they are too long and slender, and also sometimes for the sake of uniformity, when they grow in a wrong direction. In describing the structure of the grinders, it must be observed, that a grinder is composed of several distinct laminae or teeth, each covered with its proper enamel; and that these teeth are merely joined to each other by an intermediate softer sub- stance, acting like a cement. I accordingly use the words teeth, strata, layers, and laminae, as synonimous, when speaking of the structure of the grinders. The structure of the grinders, even from the first glance, must appear very curious, being composed of a number of perpendicular laminae, which may be considered as so many teeth ; each covered with a strong enamel, and joined to one another by the common osseous matter. This, being much softer than the enamel, wears away faster by the mastication of the food; and in a few months after some of these teeth cut the gum, the enamel remains considerably higher, so that the sur- face of each grinder soon acquires a ribbed appearance, as if originally formed with ridges. These strata, when first formed, have no firm attachment to each other, but always appear separate and distinct, when contained in their bony sockets within the jaw, after their membranes and soft parts are destroyed. Before any part of a grinder cuts the gum, there is a bony crust formed above the enamel, which gives a smoothness to the grinding surface. But, after the grinders cut the gum, and the convex surface has been worn down a little by the trituration of the food, each lamina appears to have been formed on several points*, which are covered * This appearance has been observed by Patrick Blair, m. d., f. u. s., who, in his Osteographia VOL. XVIII, 3 U 514 PHILOSOPHICAL TRANSACTIONS. [ANNO 17QQ. by a strong enamel. There are from 4 to 8 of these points, joined together by the common bony matter, which fills up the space between the enamelled portions. When the grinder is farther advanced in the mouth, its foremost laminae are gra- dually worn down by the mastication of the food; and these enamelled points or denticuli disappear, one after another, till the enamel at last runs quite across the tooth, surrounding the central part on which it was formed, and taking the irre- gular indented plaited shape of the lamellae. This bony centre on which the enamel is formed, is harder than the matter which joins the teeth together, does not wear so fast, and consequently remains higher. The number of teeth of which a grinder is composed, varies from 4 to 23, ac- cording as the elephant advances in years; so that a grinder or case of teeth, in full grown elephants, is more than sufficient to fill one side of the mouth ; in pro- portion however as the foremost layers are worn away, the succeeding ones come forward, to supply their places. The denticuli of which each layer or tooth is composed, are much larger, and fewer in number, in old than in young elephants; in consequence of this, the same number of laminae generally fills the jaw of a young or of an old elephant; and from 3 till 50 years, there are from 10 to 12 teeth or laminae in use, in each side of either jaw, for the mastication of the food. When several of the anterior teeth of which a grinder is composed have been completely formed, and each tooth covered with its proper enamel, they become firmly united, beginning at the fore part, by the intervention of the common bony matter, which gradually fills up the interstices between them. When the bodies of several of the anterior laminae have been connected together the in- ferior edge of each becomes united, in the same manner, to the one next it, till the whole are thus gradually joined, and form a grinder or case of teeth. As soon as the anterior part of the grinder is thus firmly united, the fangs or roots are next added: these at first appear in the form of a thin curtain or lamella of bone, extending backwards, along some of the anterior laminae, at their lower edges. A fang common to the 3 anterior teeth, first begins to be formed by the ossification shooting across from each side, in a circular direction, at the anterior portion of the first, and the posterior part of the 3d lamina. These join and become longer, assuming a conical shape: the hollow is gradually filled up by suc- cessive layers of the substance of the tooth, as the fang lengthens, till at last it becomes solid. This however does not happen, till the 3 layers to which the fang is attached are nearly worn away. When its ossification is almost completed, ano- ther process begins to take place, which is, the absorption of the fang from its ex- ternal surface. By the time that the anterior layers of the grinders are completely Elephantina, published in 1713, calls it dictations. The above work, which was put into my hands by my friend Dr. Alex. Monro, jun., since this paper was written, contains some useful information. The ingenious author had, in several particulars, a tolerable idea of the formation and structure of the grinders j yet, far from suspecting a regular succession of them, he attempts to prove such succession to> be impossible. He is equally erroneous in many other respects. — Orig. VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 5l5 worn down, both the fangs and the alveolar processes begin to be absorbed. Their places are gradually supplied by the next laminae of the grinder, and their fangs coming forward in a constant succession. When the last tooth of a grinder has advanced sufficiently in the jaw, to supply the place of its predecessor, the anterior tooth of the next succeeding grinder comes forward, to supply its place. From the peculiar manner in which the grinders are supplied from behind, but never from beneath, a preceding grinder, as is the case in the human species, and in most other animals, it must appear evident, that an elephant can never shed his teeth ; but, from this regular succession, he may, at one period, have only a single grinder in each side of either jaw; at another there may be one and part of a succeeding grinder; even a still greater variety in the appearance of the grinders will take place, according as the anterior one is more or less worn away, and the waste supplied by its successor. In this manner, the growth of new teeth, to compose a succeeding grinder, and the ossification and formation of the fangs, are constantly going on, in regular succession; so that, after the 2d year, the mouth of the elephant is constantly filled with as many laminae of the grinders on each side as it can hold. While the grinders thus advance forward in the mouth, in re- gular succession, the alveolus of each advances along with them; and as the an- terior fangs are absorbed, the same process is going on in the alveoli. In the par- tition between each alveolus there is a communication, which in young elephants is larger than in those farther advanced in years; and it is probable, that this canal or sinus between the different alveoli, admits the passage of an elongation of the membrane, from the anterior to the posterior grinder. The time requisite for the complete formation of 1 of these cases of teeth, con- stituting a grinder, varies from 2 to 6 or 8 years; and when an elephant has at- tained its full size, a considerable number of the anterior laminae must be worn away, and the fangs absorbed, before the posterior ones can be sufficiently advan- ced to cut the gum. From the curved line in which the grinders of the upper jaw advance, it must be evident, that some of the anterior laminae must be obliterated before the last can come into use: this may be made to appear more clearly, by drawing lines parallel to the surface of the grinder of the upper jaw; yet there are 10 of the posterior ones that cannot come into action, till the same number of their predecessors are worn away in regular succession. Before this could have happened, several years must have elapsed, during which the posterior laminae would have been completed; for, in the present state, the 3 aftermost layers are not even now attached to each other, or to the rest which are anterior; the membrane between, and connecting these laminae, not being ossified at the time of the animal's death. In this grinder, there are 23 laminae, which is the greatest number I have seen. In the lower jaw, the same circumstances take place : the teeth of the grinders rise by the addition of their fangs, force their way through the alveoli, and cut the gum, as they advance forward in the jaw. The grinding surface has rather a on- 3u 2 5l6 PHILOSOPHICAL TRANSACTIONS. [ANNO 1799. cave form, to adapt itself to that of the grinder in the upper jaw. The number of layers does not always correspond with those of the grinder in the upper jaw; but, like them, consists of from 4 to about 13 teeth or laminae. In both jaws, the alveoli are firmly attached, anteriorly and laterally, to the bony plates of which the jaw is composed; but at the posterior part these alveoli are separate from the jaw, and have only a membranous attachment. The alveoli terminate in an apex or point, and become thicker and stronger, as the elephant advances in years. In the lower jaw, the portion of the alveolus which is attached to the inner plate, is thick and spongy; and through the under part of this spongy substance there is a pretty large foramen, for transmitting the blood-vessels and nerves which supply the teeth and lower jaw. The alveolus of the grinder advances in the same manner in the lower as in the upper jaw ; and as the fangs are absorbed it is absorbed also. In proportion as the fangs or roots are added to the grinder, it rises through the alveolus, and cuts the gum ; at the same time the bottom of the alveolus, in which the grinder is formed, becomes more spongy, and shoots up between the fangs, firmly embracing them, and thus preventing the grinder from being shaken or dis- turbed by the trituration of the food. As the grinders of the upper and under jaws wear away, their roots are lengthened, and become more solid, by the internal addition of new matter, till the cavity is entirely filled up. This lengthening of the roots is necessary, to give that portion of the grinder in use sufficient firmness in the jaw, as well as to keep the surface at a proper level above the gum. When the anterior teeth are worn down to the roots, these, with the sockets, begin to be absorbed, to make room for their successors, which are coming forwards. The shape of a grinder of the lower jaw is very different from that of one of the upper: in the latter, the grinder advances from behind straight forwards, and the back part has a very convex shape ; whereas the lower grinder advances rather in a bent or curved direction, adapting itself to the shape of the jaw. The surface of this grinder is somewhat of a concave figure, adapted to the form of the corres- ponding grinder in the upper jaw. The upper and lower grinders, and the section of a grinder, show, in the clearest manner, the progress of ossification in the roots, and the manner in which the different teeth are joined. In a young elephant, soon after birth, the milk grinders, with their roots are completely formed ; and even the succeeding or 2d set of grinders have the roots partly added to some of the anterior teeth, which are soon to cut the gum; but the posterior layers are then without roots. Farther back in the jaw, the 3d grinder, which is composed of about 13 teeth, has no appearance of roots; nor have the different teeth any con- nection with each other, except by the common membranes. When these are destroyed, the teeth or rudiments of a succeeding grinder can be easily separated from each other. At this period, the enamel of the third grinder has not been formed, but only the substance of the teeth, which it afterwards covers, adapt- ing itself to the irregularities of the surface. When a grinder is con- siderably worn down, these irregularities of the central lamellae are evident, VOL. LXXXIX.] PHILOSOPHICAL. TRANSACTIONS. 5 17 from the enamel of each tooth being indented and puckered, as it were, all round. Having thus attempted to explain, in a clear and satisfactory manner, the progressive growth and regular succession of the grinders, I will next point out the periods in which I conceive these respective changes to take place. Here, however, I am in considerable doubt and uncertainty; but will fairly state the circumstances which first drew my attention particularly to this subject, as well as the grounds on which my conclusions have been made. In Nov. 1795, I sent a couple of elephants' heads, through my friend Mr. Fairlie, of Calcutta, to D. Scott, Esq., of Upper Harley-street, to be placed by him in some public museum*. In my letter, dated the 17th of that month, I mentioned the most remarkable peculiarities of these heads, and particularly the grinders; but at the same time made this remark, " there is only 1 tooth in each side of either jaw, till an elephant attains its full growth." On examining afterwards the heads of some younger elephants, I perceived I had made a mistake, and that there was not always only one grinder in each side of the jaw. This want of uniformity in the appearance of the grinders of young elephants, of the same size, and nearly of the same age, showed me my mistake, and puzzled me a good deal; nor did I per- ceive any means whereby I could satisfactorily and rationally account for it, till I had carefully compared a number of heads, of different ages, with each other. To effect this, I immediately began to collect the heads of such elephants as died at Tiperah, with the size and qualities of which I was perfectly acquainted : in the course of the year 17 96, I procured above 30 heads, and, beginning with the youngest of these, I arranged them as nearly as possible according to their respective ages. As it may be satisfactory to many members of the r. s., to learn the means by which I was enabled to collect the heads of so many elephants, whose heights and qualities I had accurately ascertained, I shall just observe, that between the beginning of Nov. 1795, and the 1st of April, 1796, there were 4 herds of elephants taken in Tiperah. Three of these herds were taken under my immediate inspection: the 4th, consisting of about 50 elephants, was taken by the Rajah's hunters, but was after- wards so terribly neglected, and almost starved to death, that I was requested by the Rajah to take them under my management; to this I consented, and his servants were ordered to obey implicitly my directions. In consequence, however, of the former ill treatment the elephants had received, above half of them died in the course of a few months; these, with some other casualties, enabled me to form the numerous collection above-mentioned. The elephants from which the heads were taken being well known to me, I was enabled to form a tolerable estimate of the ages of several of them ; those young ones whose ages are particularly specified, were brought forth after their dams were secured. After arranging and comparing the heads with each other, I endeavoured to ascertain the different periods necessary for the formation of the grinders, in * These were afterwards sent to the Right Hon. Sir Jos, Banks, Bart., and by him to the British Museum, where they now are.— Orig. 518 PHILOSOPHICAL TRANSACTIONS. [ANNO 17 QQ. young and old elephants, and thence to draw some conclusions, respecting the pro- gress of dentition in this useful animal. The first set of grinders, or milk teeth, begin to cut the gum 8 or 10 days after birth; and the grinders of the upper jaw appear before those of the lower one. Though this happens at first, yet in a few months the grinders in the lower jaw come forward faster than those of the upper, as I have observed in the heads of several elephants. In about 6 weeks, the first set of grinders can be easily felt, consisting of 4 teeth, viz. one on each side of either jaw; and as young elephants begin to eat grass, or some soft succulent food, before they are 3 months old, we may conclude, that the first set of grinders* have then completely cut the gum, and that dentition is not attended with any symptoms of pain, or irritation, in the system. The milk grinders are not shed, as the tusks are, but are gradually worn away, during the time the 2d set are coming forward; and as soon as the body of the grinder is nearly worn away, the fangs begin to be absorbed. I have not been able to ascertain the exact time when the 2d set of grinders make their appearance, as I could never get an elephant to open his mouth in such a manner as to permit me to examine his teeth accurately; but when the elephant is about 2 years old, the 2d set are completely in use. At this period, the 3d set begin to cut the gum. From the end of the 2d to the beginning of the 6th year, the 3d set come gradually forward, as the jaw lengthens, not only to fill up this addi- tional space, but also to supply the place of the 2d set, which are, during the same period, gradually worn away, and their fangs absorbed. From the beginning of the 6th to the end of the gth year, the 4th set of grinders come forward, to sup- ply the gradual waste of the 3d set. After this period, several other sets are pro- duced. In what time these succeeding grinders come forward, in proportion to their predecessors, I have not been able to ascertain ; but from the data already given, I conclude, that every succeeding grinder takes at least a year more than its predecessor to be completed; consequently, that the 5th, 6th, 7th, and 8th set of grinders (a further succession I have not been able to trace) will take from 5 to 8 years, and probably much longer, each set, before the posterior lamina has cut the gum. The milk grinders consist each of 4 teeth or laminae; the 2d set of grinders of 8 or 9 laminae; the 3d set of 12 or 13; the 4th set of 15; and so on, to the 7th or 8th set, when each grinder consists of 22 or 23, which is the greatest number I have observed. All these circumstances considered, I may venture to affirm, that the formation of the teeth and mode of dentition, in the elephant, has but little analogy with those of any other quadruped; nature having, by a peculiar and wonderful contriv- ance, and in the most convenient manner, supplied this animal with a regular suc- cession of teeth, till he attains a very advanced period of life. An advantage which, as far as we know, no other quadruped possesses. The mode in which the * By a set, I mean 4, one grinder in each side of either jaw. — Orig. VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 51Q elephant's grinders are originally formed, my short stay at Tiperah did not allow me sufficient opportunities to investigate; but, since my return to England, I have had frequent conversations with my friend Mr. Home on that subject, who, from an examination of the teeth brought home by me, and some preparations in the late Mr. Hunter's collection, has been able to prosecute the subject with considerable success. His observations will be laid before the e. s., immediately after the pre- sent paper, as a continuation of the same subject. XIV. On the Structure of the Teeth of Graminivorous Quadrupeds; particularly those of the Elephant and Sus JEthiopicus. By E. Home, Esq., F. R. S. p. 237. When Mr. Corse put into my hands his observations on the elephant's teeth, and showed me the teeth themselves in their different stages of growth, in illustra- tion of what he had advanced on the subject, I very readily engaged in the prosecu- tion of so curious an investigation. I examined several specimens of elephants' teeth, preserved in spirit, while in a growing state, which are deposited in Mr. Hunter's collection of comparative anatomy, and compared them with the teeth in Mr. Corse's possession. From these 2 sources, I was enabled to procure every in- formation that was required, to explain the structure of the elephant's teeth, and to point out the general principle on which all teeth are formed, that have the ena- mel intermixed with the substance of the teeth ; a subject, as far as I am acquainted, not hitherto investigated. To make my observations on the structure of the com- plex tooth of the elephant intelligible to the r. s., it appears necessary to mention, generally, the mode in which the more simple teeth of the human species, and of carnivorous animals, are formed: this knowledge will render the account of such additional parts as are met with in those of the elephant, more easily understood. The teeth of carnivorous animals are formed from a vascular pulp, of the same shape with the future tooth, on the external surface of which the substance of the tooth begins to grow, and increases till it is completely formed. The pulp is in- closed by a capsule, the cavity of which, while the tooth is growing, is filled with a viscid fluid, similar to the synovia of joints; and this fluid, by the absorption of the thinner parts, becomes inspissated to a proper state for crystallization, so as to form the enamel, which adheres to the surface of the tooth. Teeth formed in this way, are composed of 2 parts, of dissimilar texture: one, the enamel, which is striated; the other, the substance of the tooth, which is laminated, like ivory, being more compact than common bone, and less so than the enamel; but differing from both in the mode of its formation. Bones are formed in 2 different ways: those that are cylindrical, have cartilage for their basis; those that are flat, either cartilage or membrane; but in no instance in the body are they formed on a pulp. The substance of the tooth must therefore be considered as distinct from bone and may be ranked, both from its structure and mode of formation, as a species of ivory.* * The tusks of the elephant are formed on a pulp, similar to teeth. Tumors are sometimes met with 520 PHILOSOPHICAL TRANSACTIONS. [ANNO 17QQ. The teeth of the elephant differ from those just described, in being composed of a great many flattened oval processes ; these, while growing, are detached ; but when completely formed, their bases unite together, and make the body of the tooth, to which the fangs are afterwards added; and as the fangs are lengthened, the tooth rises in the jaw. This is what may be considered as the tooth itself, be- ing composed of the same materials as the teeth of carnivorous animals; but in addition there is another substance, which unites all the processes together laterally, into one mass; this is softer than the substance of the tooth, and on examination proves to be similar, in its texture and formation, to common bone. As teeth have been hitherto considered of the same texture with common bone; it is probable that nothing but the 1 substances being united in the same mass, could have led me to the discovery of their differing materially from each other. It will therefore be proper to explain, in this place, the circumstances which first gave me the pre- sent view of the subject. To obtain an accurate knowledge of the different parts of the elephant's tooth, a longitudinal section was made, of one that was full grown. This section exposed the lateral connection between the different processes, and the intermediate sub- stance which unites them into one mass; it also showed the mode in which the processes are continued into the body of the tooth and fangs. That the internal structure might be made more distinct, the surface of this section was polished very highly, which led to the discovery of the processes of the tooth having a more compact texture than the intermediate substance; for though both had the same appearance after being sawn, the processes bore a polish, which the other did not,* and were laminated, like ivory ; while the other parts were porous, like the internal structure of common bone. This led me to examine preparations of the elephant's teeth, in a growing state, preserved in spirit, which explained the mode of growth of these 2 substances to be different. In these preparations it was found, that the processes of the tooth, which may be called ivory, were all formed on so many por- tions of one common pulp, which had its origin in the jaw; and that the interme- diate substance, which may be called bone, was formed on a species of ligament situated immediately under the gum, from which membranous elongations extended into the spaces between the processes of the tooth. This structure of tooth is not peculiar to the elephant, but common to the teeth of all animals whose food requires to be ground, or much bruised, before it is in the frontal sinuses of the human body, having a perfect resemblance to ivory; they have their origin in the bony cavity of the sinus, and extend themselves into the orbit of the eye. Of these, I have seen 2 instances, and was unable, at the time, to account for them; but am now induced to believe they were formed on vascular excrescences, growing from the lining of the sinuses, similar in their organization to the pulps above-mentioned. — Orig. * A portion of the jaw itself bore the same degree of polish as the intermediate substance of the tooth. The cells in the elephant's skull are no part of its common structure; they communicate freely with the cavity of the tympanum, and are therefore appendages to the organ of hearing, which I shall explain more fully on some future occasion. — Orig. VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 521 swallowed. In the elephant's tooth, from the largeness of its size, the parts are more distinct, and more readily contrasted with each other; but in other animals, even those of a small size, as the sheep, the different structures are readily detected. It is singular that this structure should have escaped the accurate investigation of the late Mr. Hunter; particularly as the formation of the teeth was one of the first objects he employed himself on; and he continued to pursue it to the end of his life, marking the varieties which occur in different animals. The cause of his overlooking it was the following: in making preparations of horses' teeth, to show the figured appearance on the grinding surface, he rendered them black by means of fire, which did not affect the enamel, so that the white lines of the enamel were beautifully distinct on the black ground; but the bony part and the substance of the tooth were equally coloured, and had a uniform appearance. The examination of these preparations led him to believe, that the horse's tooth consisted of only 2 substances, the tooth itself and the enamel. Under this impression, Mr. Hunter examined the growing teeth of the horse, and found the pulp rising from the jaw, and the vascular membranes passing down from the gum, into the spaces between the portions of pulp; he was therefore led to conclude, that the pulp was for the formation of the tooth, and that the membranes which came from the gum were for the formation of the enamel. Having so fully explained, in the elephant's tooth, the real uses of these 2 parts, it is not necessary to say more in refutation of this opinion, which is published in Mr. Hunter's work on the teeth; but, injustice to the correctness of his other observations, I shall subjoin his account of the circumstances under which the enamel of the human teeth is formed, taken from the same work. He says, " the pulps are surrounded by a membrane, which is not connected with them, except at their root, or surface of adhesion. This membrane adheres, by its outer surface, all round the bony cavity in the jaw, and also to the gum, where it covers the alveoli. When the pulp is very young, as in the foetus of 6 or 7 months, this membrane is pretty thick and gelatinous. We can examine it best in a new-born child, and we find it made up of 2 lamellae, an external and an internal: the ex- ternal is soft and spongy, without any vessels; the other is much firmer, and ex- tremely vascular, its vessels coming from those that are going to the pulp and body of the tooth. While the teeth are within the gum, there is always a mucilaginous fluid, like the synovia in joints, between this membrane and the pulp of the tooth."* This mucilaginous fluid, I have already asserted, deposits the enamel ; which is fur- ther confirmed by the following experiments and observations. The complex tooth of the elephant, being composed of 3 different structures, each of which has a peculiar process for its formation, led to an inquiry whether the materials themselves were different, or only differently arranged. To investigate this, Mr. C. Hatchett, from a zeal to promote the pursuits of science by which he is distinguished, oblig- * Natural History of the Human Teeth, by John Hunter, p. 86. — Orig, VOL. XVIII. 3 X b2'l PHILOSOPHICAL TRANSACTIONS. [ANNO 17Q9* ingly gave his assistance, and made some experiments, the results of which are as follow. It is to be understood, that a complete analysis was never intended to be made; as neither Mr. H.'s time admitted of it, nor did it appear necessary for the object of the present inquiry. Eorper. 1. Some enamel, rasped into a fine powder, was put into a matrass, and, pure muriatic acid being added, the whole was suffered to remain without the application of heat during 1 hour; in the course of this time, the enamel was completely dissolved, with a gentle effervescence. To this solution, some sulphuric acid was gradually added, till all precipitation had ceased: the precipitate was sepa- rated by a filter, and was found to be selenite. The filtrated liquor, by evapora- tion, afforded a small additional quantity of selenite, which was also separated; after which, the liquor, being evaporated, became thick and viscid. This, when diluted with water, precipitated lime from lime-water, in the state of phosphate. To an- other portion, solution of acetite of lead was added, and caused an immediate pre- cipitation of a white matter, which, when dried and sprinkled on burning charcoal, produced a light and smell like phosphorus; it was soluble in nitrous acid, and was thus to be distinguished from muriate or sulphate of lead. Exper. 2. Some of the raspings of enamel were dissolved by digestion in nitric acid, and when the solution had been diluted and filtrated, it was saturated with carbonate of ammonia. The precipitate thus produced was collected, and edulco- rated in a filter. The small excess of carbonate of ammonia, in the filtrated liquor, was saturated with acetous acid; after which, the phosphoric acid was precipitated, by solution of acetite of lead. On examining the first precipitate, or that produced by the carbonate of ammonia, it was found that it was still composed of lime, com- bined with a portion of phosphoric acid, instead of carbonic acid, which might have been supposed. To effect therefore a complete separation of the 2 ingredients, lime and phosphoric acid, acetous acid was poured on the precipitate, by which it was immediately dissolved. The whole of the phosphoric acid was then separated from this solution, by acetite of lead; after which, lest any lead should be present, the liquor was saturated with pure or caustic ammonia, and the lead was separated by a filter; lastly, the lime which remained dissolved was precipitated, in the state of carbonate, by carbonate of ammonia. The enamel has been supposed, not a phosphate but a carbonate of lime. This error may have arisen from its solubility in acetous acid or distilled vinegar; but the effects of the acetous acid are, in every respect, the same on powdered bone as on the enamel. Consequently, when enamel, or bone, is put into a glass matrass containing acetous acid, placed in a sand bath, the portion which is dissolved, is not, as has been supposed, carbonate but phosphate of lime; for if to the filtrated solution nitrate or acetite of lead is added, a precipitate is produced, of phosphate of lead, in the same manner as when nitrate or acetite of lead is added to urine. This mode of treating substances supposed to contain phosphoric acid, as bone, &c. Mr. Hatchett has found of great utility; because, by this means, he can detect VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 523 phosphoric acid, when the substance is in too small a quantity to be examined in any other manner. Similar experiments, on the substance of teeth formed on pulps, and on common bone, afforded similar results. Mr. Hatchett considers lime and phosphoric acid to be the essentially constituent principles of these 3 different structures ; and any difference that is met with, only seems to be that which would constitute species of the same genus, similar to what is found in the mineral kingdom, under lime-stone, marble, and calcareous spar; these differ only by a small change in the proportions of their constituent principles, and by a different arrangement of their integrant particles. The head of a human thigh bone was found, some years since, with a thin crust of highly-polished enamel, similar in some respects to that of the teeth, on a portion of its surface, an inch and half in length, and an inch in breadth; the cartilage having been previously removed by disease. This uncommon appearance, at the time, could not be ac- counted for; but the fore-mentioned observations, on the formation of the enamel of the teeth, appeared to throw some light on it; and Mr. H., at my request, made the following experiment, to determine whether the synovia, in a healthy state, contains phosphate of lime. 960 gr. of synovia, by a gradual evaporation, afforded 21 gr. of a substance which resembled dried glue. This being collected was put into a small porcelain crucible, which, placed in a larger crucible, was exposed to a red heat, during nearly an hour. The matter in the porcelain crucible was much reduced in bulk, and appeared like a glazing, thinly spread on those parts of the crucible which had been in contact with it in its former state. Boiling distilled water was digested on the matter in the crucible, for some time. This water afterwards afforded, with acetite of lead, a copious precipitate of phosphate of lead; but no appearance of lime could be ob- tained. On the residuum in the crucible, acetous acid was digested, which was afterwards divided into 2 portions. To one of these, solution of acetite of lead was added, and as before afforded a plentiful precipitation of phosphate of lead. To the other portion was added oxalic acid, by which a small quantity of a precipitate was obtained, which was an oxalate of lime. Phosphate of lime is therefore present in synovia, though but in a small quantity; and as, from these experiments, there is reason to believe, that more phosphoric acid was obtained than was requisite to saturate the lime, it seems probable, that part of it was combined, in the synovia, either with soda or ammonia; and this accounts for the part dissolved by the dis- tilled water. M. Margueron, in the Annales de Chimie, (vol. 14, p. 123,) estimates the pro- portion of water in 288 gr. of the synovia of an ox at 232 gr. The other ingre- dients therefore amount to 56 gr.: but by evaporation Mr. Hatchett obtained, from 960 gr. of synovia, only 21 gr. of residuum; which proves that the proportion of water is much greater; for 56 to 288 is as 1 to 5.14; but 21 to 960 is as 1 to 45.7 J. It is possible, that the proportion of water to the other ingredients may not always be the same. M. Margueron also probably estimated the albuminous matter, &c. 3 x2 524 PHILOSOPHICAL TRANSACTIONS. [ANNO 1799. in a moist state; for, without one of these suppositions it is impossible to reconcile such a very great difference. By these experiments of Mr. Hatchett, phosphate of lime was ascertained to be present in the synovia; which though in a very small quantity in the natural state of that fluid, explains the mode by which the crust of enamel on the head of the thigh bone could be produced, when by a morbid action of the parts, the quantity of phosphate was preternaturally increased. A mixture of bony matter with the enamel and the substance of the tooth is a structure, as has been mentioned, not confined to the elephant: it is common to all truly graminivorous quadrupeds. But the whole number of grinding teeth belonging to each side of the jaw being confined in a case of bone, so as to form 1 large grinding surface, and the teeth being pushed forward from behind, instead of a 2d set being formed immediately under the fangs of the first, as in other animals, are peculiarities not met with in any teeth hitherto described, except those of the elephant. These peculiarities have however been ascertained, in the course of the present inquiry, to belong to the Sus ^Ethiopicus ; a skull of which, with the teeth, is pre- served in Mr. Hunter's collection. The particular species to which it belonged was determined, by its exact similarity to a skull, without the grinding teeth, in the British Museum, marked, in Dr. Solander's hand-writing, Sus JEthiopicus, from Guinea. As it has been ascertained by Dr. Solander to come from Guinea, there is reason to hope so curious a species of the hog will attract the notice of natu- ralists, and be the means of perfect specimens being introduced into this country. From the appearance of the teeth in the perfect skull, the animal had probably arrived at its full growth, and only 1 grinder remained on each side of the jaw, consisting of 7 different processes, cased with bone, similar to those of the ele- phant. The grinding surface of those processes which had their points worn down sufficiently to show a transverse section, exposed 3 oval portions of tooth, sur- rounded by enamel, inclosed in bone; which is more like the tooth of the African elephant than the Asiatic, and makes another variety of form of these processes. The tusks of the Sus iEthiopicus are uncommonly large, and in their structure resemble those of the elephant. The skull was shown to Sir Jos. Banks, whose readiness to forward the labours of those who engage in the pursuits of science, by liberally communicating to them his own knowledge of the subjects connected with their inquiries, is sufficiently known to the members of the r. s. He identified the species of the genus to which the skull belonged, in the manner above- mentioned; and, by an accurate search among the skulls of animals deposited in the British Museum, discovered a small head in a dried state, which, when pro- perly macerated and cleaned, proved to be that of a young Sus ^Ethiopicus, whose teeth were in a growing state, and enable me to explain all the necessary circum- stances, respecting this curious mode of dentition. The grinding teeth in this young head are distinct from each other, and 4 in number, on each side of the jaw. That which is most anterior is the smallest, and has a grinding surface only equal VOL LXXXIX.] PHILOSOPHICAL TRANSACTIONS. «>25 in extent to that of 1 of the processes contained in the large tooth of the full- grown animal: the second has a grinding surface equal to that of 2 such processes: the 3d is still larger, its surface being equal to that of 3 processes. These 3 teeth, in their general appearances, resemble those of the common hog; they have also the same kind of fangs; their only peculiarity is, the enamel being intermixed with the substance of the tooth, but without any bony matter surrounding it. The 4th or last tooth is very different from the others, and exactly resembles that found in the large head, only that this is in a growing state. It is composed of 7 processes, united together; these are in different stages of growth, fitting them to come for- ward in succession, similar to those of the elephant. The 2 first have their grind- ing surface worn smooth: the points of the next 2 have recently cut the gum; and the other 3 are still concealed in the jaw, not being completely formed; of the last of these the first rudiments only are to be seen. This large tooth, which may be considered to be a 2d set of teeth, as the concealed processes enlarge, advances forwards, pushing the other teeth before it: the most anterior of these, as soon as its body is worn away, has its fangs removed by absorption, and drops out : the same thing takes place with the 2d and 3d; and in this way room is made for the large 1 to supply the place of all the others. These peculiarities in the teeth of the Sus iEthiopicus, led to the examination of the teeth of the other species of the same genus, all of which appear to resemble the human grinders, only that the last in the jaw has a broader grinding surface than the rest, which is common to most quadrupeds. It is worthy of remark that the number in each side of th.e jaw in the common hog is 7 ; in the Pecary, 6; in the Babyroussa, 5; and in the Sus ^Ethiopicus, till a certain age, 4. It is curious, that one species of a genus should differ so widely from all the others, in respect to its teeth ; and should be allied to the elephant in the structure of its tusks, the mode of formation of the grinding teeth, and the manner in which they succeed each other. From these circumstances it appears that the Sus ^Ethio- picus, in a natural state, is supplied with a different kind of food from that of other hogs, and is an animal of greater longevity. On comparing the internal structure of the elephant's tooth with that of the horse, cow, and sheep, it was found, that they were similar, in having an inter- mixture of bone with the substance of the tooth, but that they differed materially from each other in the proportions and situations of the bony portions. Each of these animals having the grinding surface of their teeth adapted for particular kinds of food, the parts composing that surface are variously combined, so as to answer the purpose for which the teeth are intended. In all of them, the mode of growth is the same; the substance of the tooth is first formed, and the bony part is after- wards adapted to the irregularities of that surface. In the horse's grinding teeth the processes are 2 in number; and, in an early stage of their growth, they appear, as well as those of the elephant, to be separate teeth ; they differ however extremely 526 PHILOSOPHICAL TRANSACTIONS. [ANNO 1790. in their shape, forming irregular cylindrical tubes, the central part of which is filled up by the projecting membranes from the gums, that are to be changed tor bone. The division of the tooth into 2 parts, is very distinct in the shedding teeth, but not in the 2d set or permanent teeth. These 2 portions of bone in the middle of the tooth have frequently a hole in them, probably the passage of a blood-vessel, never completely filled up, and the food getting into it, as the tooth is worn down, considerably increases its size. Besides which, there is a portion of bony substance surrounding a great part of the outside of the tooth. In the cow's grinding teeth, there are 2 portions of bony substance in the middle of the tooth, as in the horse, in shape of crescents, and a very small por- tion in the hollows on the outside of the circumference of the tooth; but none on the projecting parts. In the grinding teeth of the sheep, the middle portions of bone are similar to those of the cow, but on a much smaller scale; there is no portion of bone on the outside of the tooth. It is not to be wondered at, that there is so great a variety in the grinding surfaces of the teeth of different genera of graminivorous quadrupeds, each no doubt adapted to the kind of food they are in a state of nature destined to live on, since there is even a variation between the teeth of the African and Asiatic elephants. In the African elephant, the processes of which the tooth is composed are not flattened ovals, as they have been described in the Asiatic, but are in the form of an oblong square or parallelopipedon, so that, in the middle line of the tooth, the processes are in contact with each other, though at no other part; by this means, the middle line of the tooth is the hardest; the whole surface therefore does not wear regularly, as in the Asiatic elephant, but with a ridge in the middle. Having, by the foregoing observations, established a well marked characteristic dis- tinction between the teeth of truly carnivorous and truly graminivorous quadrupeds, I was desirous of knowing how far this general rule applied to quadrupeds at large, and if it did not, in what animals the teeth were differently formed. The teeth of the hippopotamus and rhinoceros are found to differ in their structure from those above described, partaking in some measure of the properties of both, and forming 2 very curious links in the chain of regular gradation between the one and the other. The grinding teeth of the hippopotamus are made up of the substance of the tooth and enamel only, having no portion of bone mixed with the other parts; but, what is I believe peculiar to them, the enamel pervades the substance of the tooth to a considerable depth, so as to be intermixed with it. The grinding teeth of the rhinoceros have a peculiarity of a very different kind: they also are only composed of the substance of the tooth and enamel; but the tooth is so formed as nearly to surround a middle space, which, were it filled up with bone, would make a truly graminivorous tooth, not unlike those above described. This middle space is left open, and becomes filled up with the masticated food, which falls into it, and can- not afterwards be readily removed; so that the grinding surface will be always kept VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 527 irregular, and in a still greater degree than in any of the other teeth which have been described. It is highly probable that there are many other varieties in the structure of the grinding teeth of quadrupeds, but these will be sufficient to illustrate the general principles on which such varieties depend. XV. On the Quantity of Tanning Principle and Gallic Acid contained in the Bark of various Trees.* By George Biggin, Esq. p. 25 Q. The bark of trees contains the astringent principle, called gallic acid, and also that principle which has a peculiar affinity to the matter of skin, and which, from the use to which it is applied, is called the tanning principle. But in the pre- sent mode of tanning bark is applied in mass to the skins; consequently both prin- ciples are applied. It remains for examination, whether both principles are useful in the process of tanning: for, if they are not both useful, probably one is detri- mental. To a nobleman, whose zeal on every occasion by which the sciences or arts may receive illustration or improvement is eminently conspicuous, and to whose public energy, as well as private friendship, I feel myself much indebted, to his Grace the Duke of Bedford, I owe the means of prosecuting some experiments on this subject. His Grace, by collecting a variety of barks at Woburn, gave me an opportunity of making some experiments to ascertain the quantity of tanning principle and gallic acid each bark contained. For that purpose, 1 made use of the following methods, according to the principles laid down by M. Seguin. By dissolving an ounce of common glue in 2 lb. of boiling water, I procured a mucilaginous liquor, which, as it contains the matter of skin in solution, is a test for the tanning principle. By a saturated solution of sulphate of iron, I obtained a test for the gallic acid. I then took 1 lb. of the bark I meant to try, ground as for the use of tanners, and divided it into 5 parts, each part being put into an earthen vessel. To 1 part of this bark I added 2 lb. of water, and infused them for J hour. Thus I procured an infusion of bark, which I poured on the 2d part of the bark, and this strengthened infusion again on the 3d part, and so on, to the 5th. But as a certain portion of the infusion will remain attached to the wood of the bark, after the infusion is poured or drawn off, I added a 3d lb. of water to the first part, and then followed up the infusion on the several parts, till the 3 lb. of water, or so much of them as could be separated from the bark, were united in the 5th vessel; from which I generally obtained 1 pint of strong infusion of bark.-f~ To a certain quantity of this infusion I added a given measure of the solution of glue; which formed an immediate precipitate, that may be separated from the infusion by filtering paper. When dried, it is a substance formed by the chemical union of the matter of skin with the tanning principle, and is in fact a powder of leather. By * This inquiry has been further prosecuted by Mr. Davy in a paper inserted in the Phil. Trans, for the year 1803. f The specific gravity of this infusion was ascertained by an hydrometer whose gradations are inverse to those of a spirit hydrometer. — Orig. . 528 PHILOSOPHICAL TRANSACTIONS. , . [ANNO 1799* saturating the infusion with the solution of glue, the whole of the tanning prin- ciple may be separated by precipitation. For the gallic acid. — To the pound of bark left in the earthen vessels, and already deprived of its tanning principle by these quick infusions, I added a given quantity of water, to procure a strong infusion of the gallic acid, which requires a longer time, say 48 hours. This infusion, when obtained pure,* affords little signs of the presence of the tanning principle, when tried by the test of the solution of glue; but, with the solution of sulphate of iron, it gives a strong black colour, the common black dye, which differs in density, according to the quality of the bark: this may be further proved by boiling a skain of worsted in the dye, by which the gradations of colour will be very perceptibly demonstrated. Having thus obtained a point of comparison; by making a similar infusion, under similar circumstances, of any bark, or vegetable substance, and paying strict attention to the specific gravity of the infusion, the quantity of precipitate of leather, and the density of colour pro- duced by given quantities of one or the other test, the result will be, a compara- tive statement of the respective powers of any bark, or vegetable substance. This comparative statement I conceive to be sufficient for all commercial purposes. As oak bark is the usual substance employed in the trade of tanning, if a quantity of tanning principle is found to be contained in any other bark or vegetable, the com- mercial utility of that bark or vegetable may be determined, by comparing its quantity of tanning principle and price with those of oak bark. For an accurate chemical analysis, I have tried a variety of acids, and simple and compound affinities; and having pursued the above experiments, at the same time that I was employed on some in dying, I found the muriate of tin (the method of using which is described by Mr. Proust in the Annales de Chimie), very conve- nient. A solution of it, being added to the infusion of bark, forms a precipitate with the tanning principle, leaving the gallic acid suspended: the precipitate is of a fawn colour, and is composed of tanning principle and oxydated tin. By these means, I have been enabled to form a comparative scale of barks ; which however I do not produce as accurate. Oak bark, in its present state, as procured for com- mercial purposes, differs very much in quality, from accidental circumstances: the season of the year in which it is collected occasions a still more important differ- ence, consequently the scale now produced must be very imperfect; but I am of opinion, that by the pursuits of scientific men who may be inclined to investigate this subject more fully, a very accurate scale may hereafter be formed. In the following scale, I have taken Sumach as the most powerful in the comparative statement; leaving however a few degrees, for a supposed maximum of tanning principle, which I reckon 20. * It is hardly possible, from the intimate connection of the 2 principles, to separate them entirely by infusion: in the infusion of tanning principle, there will always exist a little gallic acid; and, in an infusion of gallic acid, a little tanning principle will commonly be present, unless the infusion of gallic acid is very weak, and procured by a 3d or 4th watering.- -Orig. VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 52<) Scale of Barks. Tanning principle, Tanning principle, Tanning (in grs.j, from § Tanning (in grs.j , , from § Gallic prin- a pint of infusion Gallic prin- a pint of infusion acid, by ciple, by and l oz. of solu- acid, by ciple, by and loz. ofsolu- colour. hydrometer, tion of glue. colour, hydrometer, tion of glue. Bark of Cherry-tree 8 4.2 59 Elm* 7 2.1 28 Sallow 8 4.6 59 Oak, cut in the \ „ 01 „r» Mountain ash 8 4.7 60 winter. S V M ■ J° Poplar 8 6.0 76 Horse chesnut. . . 6 2.2 30 Hazel 9 6 3 79 Beech 7 2.4 31 Ash 10 6.6 82 Willow (boughs) .8 2.4 31 Spanish chestnut. 10 9.0 98 Elder 4 3.0 41 Smooth oak 10 9.2 104 Plum-tree 8 4.0 58 Oak, cut in spring. 10 9.6 108 Willow (trunk) . . 9 4.0 52 Huntingdon or / Sycamore 6 4 1 53 Leicester willow \ 1U *w*1 luy Birch 4 4.1 54 Sumach 14 16.2 158 It is to be observed, that the barks do not keep any respective proportion in the quantity of gallic acid and tanning principle contained in each; which is an evidence of the distinctness of principle, and may perhaps open a new field for saving oak- bark in dying, as the willows, sallow, ash, and others, produce a very fine black. It is also worthy of observation, that the quantities of gallic acid and tanning prin- ciple do not differ in equal proportions, between the winter and spring felled oaks. This fact may lead to the discrimination of the proper time for cutting; which is probably when the sap has completely filled and dilated that part of the vegetable intended for use. This will make a difference in the season of cutting oak, elm, and other trees, shrubs, &c. Leaves should be taken when arrived at their full size, and then dried under cover; for, as the tanning principle is so soluble, and the substance that contains it so thin, in a leaf, the dew alone might dissolve it. Finally, as the gallic acid does not seem to combine with the matter of skin, and as its astringency will corrugate the surface, we may I think conclude, that its pre- sence in tanning is not only useless, but detrimental. XVI. On the Resolution of Algebraic Equations : attempting to distinguish parti- cularly, the Real Principle of every Method, and the True Causes of the Limi- tations to which it is subject. By Giffln Wilson, Esq. p. 265. 1. The practical management of algebraic equations, as far as respects the solution of problems depending on them, is well understood; but their general theory, being considered as an abstruse and purely speculative subject, is no where, that I have seen, so fully analysed, as with all the assistance to be derived from the application of the principles of combination, it appears it might be. — 2. The diffi- culties under which the higher branches of algebra still labour are generally known. No degree of equations beyond the 2d, is yet perfectly resolved : cubics present frequently an irreducible case: biquadratics have, by several methods, been reduced * The infusion of the elm was so loaded with mucilage, that it was with difficulty I could separate the tanning principle, or try the specific gravity. — Orig. YOL. XVIII. 3 Y 530 PHILOSOPHICAL TRANSACTIONS. [ANNO 1799. to cubics; but no formula exhibiting to the eye the actual resolution of a biqua- dratic has yet appeared; and for the 5th degree, and all upwards, not even a clue which promises a general resolution has been struck out, by the continued labour and ingenuity of mathematicians for several centuries. 3. This failure in the chain, beginning at the 3d degree, and its breaking off entirely after the 4th, have been very puzzling and mortifying circumstances to the cultivators of algebra. Having in the first degrees proceeded on apparently very general principles, and made a seeming progress towards a general resolution of equations, it is provoking to find it suddenly interrupted, not to be resumed by any contrivance. Various causes have been assigned for so remarkable a difficulty: but the generality of those causes, as commonly given, do not reach the principle. It has been usual for operators, when they found their methods fail, to look back till they could detect some inconsistence or impossibility in their work, and to sup- pose the difficulty explained, by pointing out the period at which such an error is made. The power and richness of the algebraic calculus affords numerous ways of compassing the same thing, and, as all of them fail when applied to this object, there is necessarily a point in every one of them, at which some inconsistence or impossibility is introduced: thence, a number of different causes may be imagined. In Dr. Waring's Meditationes Algebraicae, p. 1 82, may be seen several concurrent reasons assigned, why the methods there shown, and Dr. Waring's own, un- doubtedly the most general of any of them, since it proceeds on one principle to the 5th degree, cannot apply further: but all reasons drawn from the data of any particular method, like that commonly given for the imperfection in Cardan's Rule, which I shall examine hereafter, though very just in themselves, cannot be con- clusive: they indisputably show why the precise method to which they respectively apply must fail; but that does not exclude the expectation that some other, founded on different principles, may succeed. The question therefore recurs: Is there not some paramount fundamental reason for this general failure ? If there can be shown to be any thing in the nature of abstract quantity, which governs the several orders of quantities from which equations are framed, and leads directly to the distinc- tions and limitations practice discovers, that will reach the difficulty at its source, and afford the satisfaction desired. 4. I think, that by turning the course of our inquiry rather to examine how we come to succeed at all, in resolving any degree of equations, than why our success is so limited, the true principle on which their resolution must depend will appear; and with what probability, and by what means, if possible, we may expect to render our methods more perfect. With this idea, I shall take a concise view of the nature and resolution of equation in general; pointing out the common diffi- culty, and by what circumstances that difficulty is, in certain cases, lessened or removed; confining myself always to the principle of each step, and a strict analysis of the result, avoiding all detail of mere operation ; and, without pretending to much novelty on a subject already so beaten, I persuade myself, such an inves- VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 53 1 tigation will lead to some conclusions which have not been remarked, and which are both curious and important. On the Resolution of Equations in General. 5. Equations, in that part of algebra which treats of their general resolution, are usually considered to be reduced to one general form, for the greater convenience of comparing them, i. e. to their lowest rational dimension, with unity always for the co-efficient of the highest power of the unknown quantity; in which state, every simple equation is already resolved. The resolution of all other degrees is the finding the simple equations of which they are compounded: but to do this in a general manner, it is evident we must seek, instead of the particular equations themselves directly, a general expression representing them all; which general ex- pression is called the formula of resolution, such as, the common quadratic resolu- tion, or that given for cubics by Cardan's Rule. 6. These formulae, properly speaking, are rather the reversion of an equation, than the resolution of it: for though the unknown quantity be evolved or reduced to a simple dimension, the known parts are necessarily involved or affected with a surd at least as high as the dimension of the equation, in order to exhibit the proper number of correspondent values belonging to the unknown quantity in an equation of that degree. Thus, the equation, x1 — px -f- q = 0, and its common resolution x = — — -~— — , are both the same quadratic; only, under the first form, the unknown quantity, being of the dimension of the 2d degree, has 2 values; whereas in the 2d form it has only 1, and the double value is transferred, by the quadratic surd, to the known parts on the opposite side of the equation. Thus also, the equation x3 — qx + r = O, and the Cardanic formula belonging to iU = ^[-y + ^(J-f^)J + ^[--£ - 2 — 1q will be the sum of their squares; and therefore, if both p and q vanish, the sum of the squares of the roots must vanish also; which can never happen with real quantities. Besides this, in attempting to destroy many intermediate terms at once, we know by experience, that the equations which be- come incidentally necessary to be solved, rise to a much higher dimension than the given equation ; so that our labour, in this respect, defeats itself. 10. Nor will these difficulties be avoided, if we abandon the idea of a general resolution, and attempt to work out the roots separately: though the number of co-efficients is always sufficient to afford a distinct equation of each root, and there- fore, by the common principles of indeterminate equations, will clearly determine them all; and would also find them, if the equations afforded by the co-efficients were all of the same degree; but they rise successively, and, from the drawing them together, in order to expunge the several unknown quantities, the index of the reducing equation increases so as to defeat the operation. To show this, let us recur to the general equation before given, xn — pxn~x -J- qx"'* — rx"~3 -f- sxn~* = O; suppose its n roots to be represented by a, b, c, d, &c. w;-f- then, by the construc- * Some algebraists, affecting to reject the use of negative quantities, have been compelled to dispute the generally received theory of the construction of equations; but they have not been able to suggest any other. — Orig. + The nature of the roots is not material in this place; whether affirmative or negative, real or ima- ginary, they have just the same operation in forming the co-efficients of the equation. I have however throughout chosen, wherever I could, to give examples capable of being tried by real and affirmative roots; and, for that purpose, have uniformly made the signs of the co-efficients alternately affirmative and negative. — Orig. VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 535 tion of equations, we have n distinct equations from the several co-efficients in succession; viz. a _|, /) _[_ c _|_ d &c -\- n in number n = p, n i ab + ac + ad &c n X — 37* = 7, abc + abd kc w X — J— X -~- = r, abode 8cc. 77, or the product of them all, being the co-efficient of the last term. Now, as we haven equations, and n indeterminate quantities, it is evident, that by employing each equation successively to determine one quantity, the whole will be determined. But the equations are not all of the same degree: the first, is a simple equation: the 2d, being composed on one side wholly of products by two is in degree a quadratic: the 3d, for the 6ame reason, a cubic: and so on. If the first of these equations be used to determine a, we shall have a = p — b — c — d &c# — n; inserting that value for a in the 2d equation, it becomes the quadratic pb — /}2 4. pc — c2 -f- pd — d2 — be — bd &c. = q. If that quadratic be solved to determine b, and the values of a and b be inserted in the 3d equation, it becomes the cubic c3 &c. . . = r. Now, the quadratic having 2 roots, its solution will have introduced a quadratic surd. Before therefore we can proceed to employ the 3d equation to determine c, it must be squared to clear it of that surd, and of course will then rise to the 6th degree. The solution of such a dimension, if admitted for the present to be equally possible, must introduce higher radicals; and, by the intrusion of these superfluous roots at every stage, our labour increases, instead of diminishing. This is the difficulty alluded to before; and, as we have appropriated already all our subordinate equations, we have nothing to oppose it. It therefore seems hopeless, to expect to make any general impression on indeterminate equa- tions, without more help, beyond the mere knowledge of the constitution of the co-efficients. 1 1. This difficulty however is wholly removed by the least circumstance that dis- closes any particular relation among the co-efficients of an equation, independent of the general law of their construction. This of course, whenever it occurs, fur- nishes new conditions and means of comparing the terms. Every particularity in the co-efficients that gives specific varieties to the forms of equations, must, from the nature of their construction, have its source in some particular relation between 2 or more of the roots, and therefore, as far as that relation extends, detects them infallibly. The observation of the forms and relations of the co-efficients under different species of equations, and the correspondent inferences to be drawn, as to the connection of their roots, would form a curious and very useful part of a com- plete treatise on the whole doctrine of equations, which is a work much wanted. The most striking of these relations will be obvious, or familiar, to the reader who has at all considered the nature of the subject; such as, that equations deficient in every alternate term arise from pairs of equal roots with opposite signs, ± a, ± b &c. ; that those whose terms on both sides the middle term are alike, which are 536 PHILOSOPHICAL TRANSACTIONS. [ANNO 17QQ. generally called recurring equations, arise from pairs of roots, of which each pair 11 contains a quantity and its reciprocal, a, -, Z>, ^, &c. ; together with Maclaurin's demonstration of the particularities of the co-efficients when an equation has equal roots.* And the extent to which these notices might easily be carried, from ob- servations of the effects of the different sorts of proportion, and all other relations, is prodigious. But my present concern is merely with the result, supposing from any means a relation to be previously discovered affecting any number of the roots. For example, — suppose, in the above given equation, of1 — px*~ ' -f- qx"~* — rx?~* + sof* &c. = 0, whose roots we called a, b, c, d, &c. . . . ?i, we happened to know that 2 of the number, a and b, were equal; then, since they might both be ex- pressed by the same character, the n roots of the equation might now be repre- sented by only n — 1 distinct characters; and therefore, of the subordinate equa- tions derived from the construction of the co-efficients, 2 might be employed to determine one root, a and b being equal, the equation furnished by the value of the co-efficient jb, and also that furnished by the co-efficient q, may be both toge- ther used to determine the same quantity. But, if any quantity a be a root of an equation, the simple equation x — a = O must be a divisor of that equation;-}- therefore here a; — a must be a common divisor of the 2 equations furnished by/> and q, and consequently may be found, without resolving either of them, by con- tinual division or subtraction, according to the ordinary rule for finding the com- mon measure.;}; 12. Any other relation from the knowledge of which one character may be made to represent two or more roots, evidently answers the same end. Indeed all rela- tions of that kind may be converted into equality itself, by taking, instead of the given equation, some other properly derived from it. Thus if, instead of a and b being the same, b had been supposed the negative of a, or — a, and then, instead of the former equation, that of the squares of the roots were taken, the relation would be made equality; for a and — a have the same square. If arithmetical proportion was known to be the relation of any number of the roots, by taking the equation of their differences, it would also be converted into equality. 13. If 3 or more roots, or any number of parcels of roots, are known to be re- lated, and their common relation be used to represent them, of course the number * Vide Maclaurin's Algebra, chap. 4, p. Ifj2, et infra. f Vide Sanderson's Algebra, vol. 2, p. 679, 6*80, art. 432, and all algebras on the method of divisors. — Orig. \ Vide Sanderson's Algebra, quarto ed. vol. 1, p. 86", 87, S8, where the rule is well given; and Maclaurin's Algebra, p. 2, cap. 4, p. J 62; or Mr. Hellins's Essay on the Reduction of Equations having equal roots. But of the last it should be observed, that some qualification must be made to the assertion, that the reduction may be carried on till a simple equation is obtained. In cases where there is only one pair of roots equal, that proposition is undoubtedly true ; but, if 2, 3, or more pairs of roots are equal, the reduction can only be carried down to a quadratic, cubic, &c. for, every pair of equal roots being equally to be found by the method, of course the final or resulting equation must be of a dimension as great as their number. — Orig. VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 537 of distinct characters to be determined will proportionally be diminished : and as the number of subordinate equations furnished by the co-efficients remains always the same, while the dimension of the proposed equation is unaltered, more of them may be used together to discover the related roots, and their investigation be pro- portionably facilitated. This single observation, in the hands of a skilful analyst, is sufficient for the reduction, if not the solution, of any particular numeral equation whatever, and the more so the larger its dimension : for, from the endless variety of relations numbers bear to each other, hardly any set of them can occur, as the co-efficients of an equation, or perhaps exist, that, on being compared, do not ex- hibit some peculiarity, of greater or less extent, sufficient to afford a clue to the cor- respondent relation in their roots. And if no such clue is immediately given by the equation itself, taking the equation of the differences or sums in pairs, or of the squares, &c. of the roots, will soon find one. But, as peculiarities of that sort, though never so frequent, may be deemed always accidental, and evidently no gene- ral method can be founded on them, even where the co- efficients are given, it may be asked, how any use can be made of them in cases of indeterminate equations ? 14. To this I answer, that there are some properties of quantities that depend only on the index of the equation, without any regard to the value of its co-effici- ents ; or, in other words, there are some peculiar properties which merely depend on the number of any set of quantities, abstracted from all consideration of their nature and values. For example, 2 quantities a and b have their differences the same quantity a — b, only taken both affirmatively and negatively, a — b and b — a; when squared, these differences become equal ; a2 — lab + b2 is the square of both : therefore, let the quantities themselves be chosen as they may, the equation of the squares of their differences must have both equal roots, and consequently be reducible by the reasoning in art. 11, 12, and 13. Again, 3 quantities, however distinct in themselves, give a set of differences marked with a peculiar relation, any 1 of them being equal to the 3d ; a, b, c, being 3 quantities, (a — b) + (b — c) = a — c. Also, if the 3 quantities be so chosen originally as to have their sum equal to nothing, one of them must necessarily be equal in magnitude to the sum of the remaining two ; and therefore, whether taken simply or- summed in pairs, their relative magnitudes must remain the same. Again, 4 quantities, of any sort what- ever, may be pursued to a constant relation, though somewhat , more remote, and grounded on very different causes ; viz. a, b, c, d, being 4 quantities, from their combinations by pairs, ab, ac, ad, be, bd, cd, 6 in number, added together two by two, thus, ab -f- cd, ac + bd, ad -f- be, 3 quantities are formed, sufficiently dis- tinguished from the group of similar combinations to be found separately, as will be shown hereafter. And also, if the 4 quantities are originally so taken as to have their sum equal to nothing, their sums in pairs, though 6 in number, will be re- duced to 3 in effect; for, if a + b + c -j- d = O, by transposition, a + £ = — c — d, a -\- c =■ — b — d, a-\-d= — b — c, i. e. 3 of the 6 must be merely the nega- tives of the other 3 ; which relation, if they are squared, will become equality, so VOL. XVIII. 3 Z 538 PHILOSOPHICAL TRANSACTIONS. [ANNO 1700. that the number of distinct squares will be only 3. These properties, though with- out any order or connection, and confined merely to particular ranks or numbers of quantities, being general to all possible or imaginable quantities of those classes afford methods general, as to those degrees, but without producing any result really general to equations at large. 15. Having shown that an indeterminate general equation cannot be resolved by any of the methods whose principle is yet known, because they are all grounded on the assumption of some particularity, either inherent in the roots, or universally communicable to them, which, so far from being general, is seldom found, and absolutely incompatible with many sorts of roots ; that the difficulty is in all cases the same, — the intrusion of superfluous roots and higher radicals ; that a relation of any kind, when known, obviates that difficulty, as far as it extends; and that some orders of quantities have generally a constant and necessary relation, more or less remote, I proceed to examine, more minutely, the application of these observations to the several degrees of equations to which they materially apply. Of the Resolution or Reduction of Equations of particular Degrees. 16. In examining those degrees of equations which submit to be resolved, I shall observe the same order as before ; i. e. first consider the power of obtaining a general formula, or complete resolution; and, if that is not attainable directly, in- quire by what general means the roots can be separately investigated, and what new forms they have taken, or what different functions of them are used in the operation. 17. If we resume the general indeterminate equation & — pxn~l -f- qxn~* — rx"~' &c. = 0, and assign the progressive values 2, 3, 4, &c. to the index n, in the first case it will become the quadratic x2 — px -}- q = O. Now as this equation has 2 roots, in order to obtain a general formula for its resolution, the first step that suggests itself is,- to inquire what is necessary to construct a general representation of 2 quantities in a simple equation. Two quantities are known to be generally expressed by means of their sum and difference ; that half their sum added to half their difference gives the greater, and the same quantities subtracted, the less. The sum being always the co-efficient of the 2d term of the equation, is given in all cases, and here the difference is readily found ; for, the square of the difference of any 2 quantities differs from the square of their sum, by a constant quantity, viz. 4 times their product or the co-efficient of the 3d term. If a and b be called the roots of the equation x* — px -f- q = 0 ; then p = a + b, andjb2 = a2 + lab + b* ; q = ab, and — Aq = — 4ab ; r the square whence a2 — lab + b* = (a — bf = p* — 4qJ ofthedif- L ference. The difference itself is therefore y/{p* — 4q). And now, being possessed of the parts required to construct a general representation of the 2 quantities, we can at VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 539 once complete the formula of general resolution of equations of this degree, viz. x = \P + 4- a/ (^>2 — 4^). This, as before observed in art. 6, is however the same quadratic, only reverted; for, the quadratic surd it contains is frequently incapable of further reduction. Therefore, generally speaking, the degree of the equation is not altered ; only the place of the index, which being first affixed to the unknown quantity, is now transferred to the known ones. But yet this resolution is, in all cases, equally true and direct ; for, involving no other radical than belongs to the degree it relates to, it faithfully exhibits the nature of the roots, and is always rational or real, or not, according as they are so. * 18. If, instead of seeking, a priori, the formula of resolution, we attempt to find the roots simply, we may instantly trace a constant connection between them, or at least between their differences; which, however the quantities are varied, are always related in the same manner, being a — b and — a + b, the same quantity with different signs, and consequently their squares precisely the same. From which it appears that the equation of those differences will always want the 2d term, or be a pure quadratic ; and that of their squares will be a perfect binomial square, having both roots equal; which roots may therefore, by the reasoning in art. 11, be certainly found. But the inference is just the same as before : the equation is not lowered in degree ; the equal relation is brought no nearer than between the squares of the differences ; and, when they are found, the same quadratic surd must be used to arrive at the roots themselves. This formula of resolution x = -rp ± -2 — 4^). is the same given for quadratics in every algebra; but it is not usually remarked, or perhaps understood, that the whole operation, however varied in appearance by setting about to complete the square, as it is called, or to destroy the 2d term, is merely employed to obtain the difference of the roots ; that, on analysing the formula, the part under the vinculum is always that difference and nothing else, and why it must be so. ]g. Next, let n = 3, and the equation bethe complete cubic x3 — • px2 -f- qx-—r = O. If we make it our first step here, as in the last case, to inquire what is necessary to construct a general representation of 3 numbers in simple equations, we shall find it must consist of the same parts, the sum and the differences: but, as the differences increase in number, to show the order in which they are taken, and the law they observe progressively, I shall subjoin a general table of the simple re - presentation of the different orders of quantities. As in every equation the sum of the roots is always given, I shall, for greater simplicity in the table, suppose it always to vanish. If then there be a series of general equations, beginning with a quadratic, and proceeding upwards with progressive indexes, in all of which the co- efficient of the 2d term p be taken = 0, and a be supposed a difference of the roots of the first, a and b 2 of the differences of the roots of the 2d, a, b, c, 3 differ- ences of those of the 3d, and so on ; in taking of which differences, no other cau- tion is necessary than that they should be similarly situated, viz. all derived tyy com- paring the same individual root with the remaining ones, as if a be taken as a root 3z2 540 PHILOSOPHICAL TRANSACTIONS. [anno 1799. and a — b be the first difference, a — c, a — d, a — e &c a n, having all the same antecedent letter, whose number will always be n — 1 , must be the rest ; then, the table will be as follows : Table of the simple Representation of the Roots of Equations of progressive Indexes. In quadratics, In biquadratics, " A + B + C In cubics, A + B *= < A — B B + C f + ^3 3 _1_ A — c 1 B ~* c 3 .4 < + I A + B 3 3 A + c In the 5th degree, A + B + C + D A — • B 2 A + B 2 — A— B— C— D. + + + A — B B -f- C B -f D 4 4 4 A — c 4 + B — C 4 — C + D 4 A — D 4 + B — D 4 + C — D 4 A + B A + C A + D In the (nth) degree, or generally, r A + B-t-c + D + E &c (» — 1) in number X = * 4- ~n — r — Z — T &c- (n ~ 2) m number n — 1 n — 1 x ' — A — B— C— D— E &C. (n — 1) x » + ^ + * + n — 1 &C. n — 1 + ^-&c. h^4,-fc n - 1 B — E -&c. n — 1 ' n — 1 20. The inspection of the table shows us, that in all cases, to construct a gene- ral simple representation of any number of quantities, and consequently to construct a direct resolution of their equation, we must first find a certain number of their differences ; but we have no general means of separating particular differences from the rest ; and the whole number of differences increases in a proportion so much greater than the number of quantities, that the former difficulty recurs, the pre- TOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 541 vious steps involve higher dimensions than the original equation. The original in- dex being n, that of the equation of the difference of the roots is n X (n — l). However, from the nature of differences, being taken both affirmatively and nega- tively, all equations formed from them must, as observed of quantities of that sort in art. 11, be universally deficient in every alternate term, which brings their equa- tion to the form of equations of only half their own index, orw X -i (n — I ) : but in this case their differences are 6", and their equation, with that consideration, is reduced no lower than a cubic form, which is the same degree with the proposed equation : therefore it does not appear that we can be enabled, a priori, to deter- mine the formula of any direct resolution of this case. 21. Let us then try to trace some relation which may convert some or all of the roots, or some regular function of them, into equal quantities ; when, the equation of that function having equal roots, of course those roots will be sepa- rately deducible, as shown in art. 11,12. In art. 14, we may remember that 2 particularities were mentioned to belong to 3 quantities, viz. that their differences were so related as to be every 2 of them equal to the 3d ; and that, if the quanti- ties themselves have their sum equal to nothing, 2 of them also must equal the 3d, and their magnitude be respectively the same, whether they are taken simply, or summed in pairs. To avail ourselves of both these properties, let us suppose the 2d term to be expunged from the given equation, which we know may always be effected, its form will then be x3 — qx + r = O *, and the sum of its roots equal to nothing. Let a and b be two of its roots, the 3d will therefore be — a — b ; take their sums by 2, — a, — b, a -f- b ; take their differences, 2a -f- b9 a -f- 2b, a — b, and their negatives, which may be divided into 2 sets whose sum is nothing, like that of the roots, viz.| __ | ~7 £ __ ° "\ ^ "~ 2« + by So tnat> from tne given equation we derive 3 others, which make a set of 4 exactly similar. 1st. x3 — qx + r = O, the given equation. 2d. x3 — qx — r = 0, that of its roots summed in pairs. 3d. x3 — 3qx -j- \/(4q3 — 27r2) = 0,~> _ . ., c ,,,..,. 4th. x3 -3^W (4?3 - 27?^) = o,} 2 Similar e(luatl0ns> formed by dividing aP — Qqx4, + 9^2 xx — (4q3 + 27r2) = 0, the equation of the differences, into 2 wanting the 2d term. 22. Now, leaving these considerations for a moment, let us speculate on the further reduction of the equation. If, instead of the present form x3 — qx-\- r = o, q could be supposed to vanish as well as p, a still more powerful additional rela- tion would be given to the roots ; for, the equation being then a pure cubic x3 = + r, its roots would obviously be the cube roots of r, and all cube roots are alike. If r be a cube, and ^r be one of its roots, the remaining two are X #r and X #r, let r be any quantity whatever, real or * Besides expunging p, the sign of q has been changed ; because, in cases of real roots, it will inva- riably become negative on destroying the 2d term. Vide note in p. 536, — Orig. 542 PHILOSOPHICAL TRANSACTIONS. [ANNO 17QQ. imaginary. But it is clear, from what has been before observed in art. 9, that tis reduction is not generally possible, since it supposes 1 contiguous intermediate terms to vanish together, which real roots do not admit of: it must therefore be effected by means of some imaginary assumption. Those who are conversant in the use of impossible quantities, will at once perceive, that the addition or subtrac- tion, (which in surd quantities is always the same thing, as they are equivocal in sign,) of the imaginary surd */ — \q to each root of the equation, will infallibly cause q to vanish, but the new roots -J , " . " •»' — a — b + */ — t?> so formed, would not have their sum equal to nothing ; and therefore, in destroying the 3d term, the 2d would be revived, so that nothing would be gained. 23. To understand how this difficulty is ever removed, let us examine particu- larly some equation that wants both 2d and 3d terms, and observe accurately the constitution of its roots. The simplest of the kind is the pure cubic x3 = 1, — 1 "^~ / — 3 whose roots are 1 , ; but, to avoid fractions in the roots, let us take x3 = 8, whose roots are (2, — jr y/ — 3. Distinguishing the real and the ima- ginary parts, the real are 2, — 1, — 1 ; the imaginary are + when its equation x3 = 24 — eTV — -r is made rational, gives the quadratic formed equation of the 6th degree, xG — 48x3 p- 576= — 64-t° » or, transposing all the terms to one side, and dividing it by 2, to reduce it, as be- fore, x6 — 6x3 -\- Vr = ° > tne same equation that results from the common methods. 2dly. The differences of the 3 differences a — b, a -j- lb, — 2a — b, are 3a, 3b, 3 (a + b), or merely 3 times the original quantities. Therefore, had the dif- ferences themselves been taken as original quantities, and binomials being formed from them, according to the directions before observed, those binomials, and the ultimately resulting cubes, would differ from the former, in nothing essential but the place of the surd. The differences which were affected with it before, would now be clear ; and the quantities themselves, or, which is the same thing, their sums in pairs, be affected with it. However, as these latter are to be multiplied by 3, that multiplication will destroy the fraction when they come again to be mul- tiplied by the surd 1/ — -i-, since 3 X V — -£■ = one of the resulting binomials will be VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 545 real, and the other 2 imaginary : the cube produced by them will therefore be real. When all the roots are real, if 2 be equal, one difference necessarily vanishes; therefore the imaginary factor will only appear about the 2 that remain ; and here again the cube produced will be real. But if all the roots are real, and unequal, their sums and differences will all be real : whence all the binomials will involve the imaginary surd ; which constitutes the irreducible case. To give examples of this, let, 1st. x3 — 1x ■+• 4 = O, a cubic equation, whose roots are 2, and — 1 4- V — 1, and — 1 — a/ — i ; the binomials constructed by taking their sums and differences as before, will be 2 -(l~^_i) = 1 + ^-1^ 2 + (1 - •— 1) = 3 - )4 -J- (f2 — 4* — qp* -L. pr _|_ -Jt^p4) x {x —'■kpy — -rP* — -kp* + r)* =0*, which when p is supposed to vanish, becomes x6 — 2qx4 -\- (q* — 4s) x1 — r2 = O. 30. These 2 methods, one applying to the biquadratic equations complete in their terms, and the other to those from which the 2d term has been expunged, are all that have yet been discovered; and, notwithstanding the number of different methods attributed to different writers, which from their manner of setting out appear distinct, they will all be found to resolve themselves, in principle, into one of these. Dr. Hutton's Mathematical Dictionary, under the article Biquadratic Equations, gives 4 methods; viz. Ferrari's, Des Cartes's, Euler's, and Simpson's; to which may be added another by Dr. Waring-f~, and perhaps many more. They proceed on a variety of different contrivances; but when analysed, and the real object gained is viewed apart from the process that led to it, Ferrari's, which is the oldest, and does not require the extinction of the 2d term, will be seen to produce the cubic x3 -— qx2 + {pr — As) x — p*s + Aqs — r2 = 0; and Des Cartes's, which supposes the 2d term to be first destroyed, terminates in the cubic-formed equation of the 6th degree, x6 — 2qx4 + {q* — 4s) x* — r* = O. The rest produce cubics, or cubic-formed 6th powers, whose roots are some parts or multiples of this last; except Waring's method, which does not expunge the 2d term, and therefore produces a cubic whose roots are part of the first. But, whether the resulting equation be that of the function, formed by summing the combinations by 2 of the roots in pairs, or summing the roots themselves in pairs, or the equation of the halves, or quarters, or doubles, trebles, &c. of those functions, is immaterial; no new function is employed, no other principle put in action, than what is de* rived from the general properties of this degree of quantities here explained. 31. Biquadratics being generally thus reducible to cubics, of course, by resolving those cubics, distinguishing what function their roots are of the roots of the ori- ginal biquadratic, they may all be found; and, for practical utility, there is no preference to be made of either of the 2 methods; for the first, though a real cubic, being formed from products of the roots, it requires a quadratic equation to obtain them after the cubic is resolved; whereas the 2d, though an equation of the 6th power, being formed from simple addition of the roots, gives them at once. But as both these cubics necessarily have all their roots real, when those of the biquadratic are so, and the resolution of cubics is in that case imaginary, it * Waring's Medit. Algeb. p. 138. f Ibid. p. 133 ; and the Appendix to Dr. Hutton'* Dictionary. — Orig. 4 A2 54S PHILOSOPHICAL TRANSACTIONS. [ANNO 1 7QQ. follows that no biquadratic having all its roots real, can admit of a real solution by either of these methods. 32. The formula expressing the actual resolution of a biquadratic has not been given; the writers on algebra going no further than to point out the cubics by means of which such a resolution may be obtained. To be sure, such a formula would be very long, and, till the imperfection in the cubic resolution, which must make a large part of it, can be removed, embarrassed with radicals, so as to be of little practical use; but it would be a valuable accession to' the theoretical part of algebra, to have the analysis of this degree carried as far as that of the preceding, by developing every part of the functions that enter into the resolution, so as to be able to compose it at once, or make a complete reduction of the equation, without the intervention of any other steps. 33. Let n be taken = 5, or any higher number. Here the number of dif- ferences is increased to 20; and the higher we go the more they increase, so that a direct simple resolution is out of the question. Nor are we yet acquainted with any peculiarity attending 5, or any higher number of quantities, on which we can ground a relation to effect a reduction of any sort; therefore no method is known for equations of this and the higher orders. Whether any may ever be discovered, it is not easy to pronounce: if the reasoning from art. 8 to art. 15, of this paper, be correct, there can be no chance, until some peculiar property of quantities of this class can be hit on. It is perhaps a discouraging presumption against the ex- istence of any such property, that no art or labour has hitherto afforded the least clue to lead to one; but, on the other hand, it is impossible to tell what general properties of quantity may remain to be discovered; and, from the great distance the peculiarities of the degrees we have treated of lie from the surface, and their total want of order or connection with each other, it may be justly expected that those of the higher degrees may lie still more detached and remote, beyond any efforts that have yet been made on the subject. The proper method to proceed seems therefore to be, abandoning all projects for the general resolution of equa- tions, to investigate regularly the abstract properties of each separate order or number of quantities, turning them into all shapes, sifting all their combinations, and constructing and examining the equations of different complex functions of them, in order to see if latent peculiarities be not to be traced out in some of them. Wherever any distinguishing property is found, it will, by the principles here explained, infallibly lead to some method for the degree to which it belongs; and whoever may be fortunate enough to discover any such property, in 5, 6, or any higher order of quantities, will have the honour of removing the important and hitherto impenetrable barrier, which has so long obstructed the further im- provement of algebra. XVIL On different Sorts of Lime used in Agriculture. By Smithson Tennant, Esq., F. R. S. p. 305. It is said, that in the neighbourhood of Doncaster, there are 2 kinds of lime VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 54Q employed in agriculture, which are supposed to differ materially in their effects. One of these, procured near the town, it is necessary to use sparingly, and to spread very evenly over the land; as a large proportion of it, instead of increasing, diminishes the fertility of the soil; and that wherever a heap of it is left in one spot, all vegetation was prevented for many years. Fifty or 6o bushels on an acre, were considered to be as much as could be used with advantage. The other sort of lime, obtained from a village near Ferry-bridge, though considerably dearer* from the distant carriage, is more frequently employed, on account of its superior utility. A large quantity is never found to be injurious; and the spots which were entirely covered with it, instead of being rendered barren, become remarkably fertile. The different properties ascribed to these 2 kinds of lime were so very distinct, that it seemed probable they could not be imaginary; and it therefore ap- peared to be worth the trouble of ascertaining them more fully, and of attempting to discover the nature of the ingredients from which the difference arose. For this purpose, I procured some pieces of each sort of limestone, and first tried what would be their effect on vegetables, in their natural state, by reducing them to coarse powder, and sowing in them the seeds of different plants. In both kinds the seeds grew equally well, and nearly in the same manner as they would in sand, or any other substance which affords no nourishment to vegetables. Pieces of each sort of stone were then burnt to lime; and after they had been ex- posed for some weeks to the air, that their causticity might be diminished, some seeds were sown in them. In the kind of lime which was found most beneficial to land, almost all the seeds came up, and continued to grow, as long as they were supplied with water; and the roots of the plants had many fibres, which had pene- trated to the bottom of the cup in which they grew. On examining the compo- sition of this sort of lime, it proved to consist entirely of calcareous earth. By- its exposure to the air for about 3 months, it was found to have absorbed -f-ths of the fixed air required to saturate it. In the other kind, a few only of the seeds grew, and the plants produced from them had hardly any stalks or roots, being formed almost entirely of the 2 seed-leaves, which lay quite loose on the surface. This sort of lime, being spread on a garden soil, to the thickness of about TVth inch, prevented nearly all the seeds which had been sown from coming up, while no injury was occasioned by common lime used in the same manner. On exam- ining the composition of this substance, which was so destructive to the plants, it was discovered to contain 3 parts of pure calcareous earth, and 2 of magnesia. The quantity of fixed air which it had absorbed, by being exposed for about the same time as the pure lime just mentioned, was only -rWths of that combined with it before it was burnt. As it seemed probable, that the magnesia contained in this lime was the cause of its peculiar properties, the following experiments were made, to determine the effects of that substance on the growth of vegetables. Some seeds, chiefly of colewort, which were preferred from their growing quickly, were sown in uncal- 550 PHILOSOPHICAL TRANSACTIONS. [ANNO 17QQ. cined magnesia; but, though they sprouted, the leaves never rose above the sur- face, and the plants were entirely without roots : nor did they appear to grow better in magnesia which had been washed in water containing fixed air. Calcined mag- nesia was however much more destructive, as the seeds would not come up in it. To compare its effects on vegetables with those of lime, each of these earths was mixed, in different proportions, with sand, in small cups, in which seeds were then sown. The lime was obtained from marble; and, before it was put into the sand, was made to fall to powder, by being moistened with water. In a mixture of 4 oz. of sand with 3 or 4 gr. of calcined magnesia, it was a long time before the seeds came up, and the plants had hardly any roots or stalks; and with lOgr. or more of magnesia, there was no appearance of vegetation. Thirty or 40 gr. of lime did not retard the growth of the seeds more than 3 or 4 gr. of magnesia, and the injurious effects were not so lasting. The lime, by absorbing fixed air, soon lost its destructive properties; so that, after keeping these mixtures 4 or 5 weeks, seeds were found to grow in that with 40 gr. of lime, nearly as well as pure sand; but, in that with 5 gr. of magnesia, they produced only the seed-leaves, as before described. It was necessary occasionally to break in pieces the sand which had so much lime, as it would otherwise have been too hard to admit the seeds to pene- trate through it. Plants will bear a much larger proportion of magnesia in vege- table soil than in sand: with 20 gr. however of calcined magnesia, in as much soil as was equal in bulk to 4 oz. of sand, the seeds produced only the seed-leaves, without roots; and with about 40 gr. they were entirely prevented from coming up. In countries where the magnesian lime is employed, it was said that the barren- ness of any spot on which a heap of it had been laid, would continue for many years. To learn how far it could by time be deprived of its injurious qualities, I procured some pieces of mortar made of this species of lime, from 2 houses, 1 of which had been built 3, and the other 8 years: they were taken from the outside of the building, where they had been exposed to the air. After they were reduced to powder, seeds were sown in them. Only a few came up, these produced merely the seed-leaves, without any roots. As plants would grow in the limestone from which this species of lime was formed, though not in the mortar made from it, I wished to know what proportion of the fixed air originally contained in the lime- stone, had been absorbed by the mortar. For this purpose, a piece of it was finely powdered, to render it of a uniform quality: it was then tried how much of this powder and of the limestone would saturate the same quantity of acid: by this means, I ascertained the proportions of limestone and mortar containing equal quantities of the magnesian lime. The fixed air being obtained from them in those proportions, and measured in an inverted vessel, with quicksilver, it was found that the mortar which had been exposed 3 years had absorbed 43, and that of 8 years, only -i^ths of the quantity originally contained in the limestone. I was not able to obtain any mortar which had been made earlier, though it might deserve to be known how much fixed air it was ultimately capable of absorbing. VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 551 Common mortar which had been exposed to the air for a year and three-quarters, had regained -iVo-tns of its full quantity of fixed air. As the preceding experi- ments were tried during the winter, in a room warmed by fire, perhaps under cir- cumstances more favourable to vegetation, the same quantity of magnesia would not be equally pernicious. Magnesian limestone may be easily distinguished from that which is purely cal- careous, by the slowness of its solution in acids, which is so considerable, that even the softest kind of the former is much longer in dissolving than marble. From this property of the magnesian limestone, there appeared to be reason for suspecting that the kind of marble which had been called Dolomite, from M. Do- lomieu, who first remarked its peculiarity in dissolving slowly, might also be simi- lar in its composition. An analysis of this substance was lately given in the Journal de Physique, but this is probably erroneous; for, on examining three speci- mens, they were found to consist of magnesia and calcareous earth, like the magnesian limestone; so that it ought, no doubt, to be considered as the same species of stone, but in a state of greater purity. The pieces of Dolomite were from different places; one of them being found among the ruins of Rome, where it is thought to have come from Greece, as many statues of Grecian workmanship are made of it, and no quarries of a similar kind are known in Italy; the 2d was said to have been thrown up by Mount Vesuvius; and the 3d was from Iona, one of the western islands of Scotland. In many kinds of common marble, small particles and veins may be observed, which are a long time in dissolving. These, on examination, I discovered to contain a considerable proportion of magnesia; but, as they were probably not quite free from the surrounding marble, I did not ascer- tain the quantity precisely. The crystallized structure which may generally be ob- served in the magnesian limestone, seems to show that it has not been formed by the accidental union of the 2 earths, but must have resulted from their chemical combination. The difficulty of dissolving it, may also arise from the attraction of the different component parts to each other. The mortar formed from this kind of lime, is as soluble in acids as common marble; and the substances of which it con- sists are easily separated. The magnesia may be taken from it by boiling it in muriated lime, and lime is precipitated by it from lime water; but neither of these effects can be produced by the stone, before it is calcined. Magnesian limestone is probably very abundant in various parts of England. It appears to extend for 30 or 40 miles, from a little south-west of Worksop, in Nottinghamshire, to near Ferry-bridge, in Yorkshire. About 5 or 6 miles farther north there is a quarry of it, near Sherburn; but whether this is a continuation from the stratum near Ferry-bridge, I have not learnt. From some specimens which were sent me, I find that the cathedral and walls of York are made of it. I have not been able to learn whether there were any shells in the limestone of the tract of country before mentioned. In Mr. Marshall's account of the agriculture of the midland counties, he speaks of the lime made at Ereedon, near Derby, as 552 PHILOSOPHICAL TRANSACTIONS. [ANNO 17QQ* destructive to vegetables, when used in large quantities. I therefore procured some pieces of it, and they were discoverd to contain nearly the same proportion of mag- nesia as that before described. In this quarry, the stone is frequently crystallized in a rhomboidal form ; and petrified shells, not calcareous, but similar in compo- sition to the stone itself, are sometimes, but very rarely, found in it. This sub- stance seems to be common in Northumberland. In the 3d vol. of the Annals of Agriculture, Dr. Fenwick, of Newcastle, observes, that the farmers of that country divide limes into hot and mild. The former of these is no doubt magnesian, as it has similar effects on the soil ; and he remarks that it is not so easily dissolved in acids as the latter. At Matlock, in Derbyshire, the 2 kinds are contiguous to each other; the rocks on the side of the river where the houses are built being magnesian, and on the other, calcareous. The magnesian rock appears also to be incumbent on a calcareous stratum ; for, in descending a cave formed in this rock, a distinct vein of common limestone may be observed, which contains no magnesia. The latter stratum is very full of shells; but though there are some also in the magnesian rock, yet they are very rare. In the following tables, containing the analysis of various specimens, some other places are mentioned where this sub- stance is found, but of which I received no further information. After it was known that the magnesian marble and limestone consisted of the 2 earths, their proportion was attempted to be discovered, by trying how much gypsum and Epsom salt could be obtained, by means of vitriolic acid, from a certain weight of each specimen. When the superfluous vitriolic acid had been evaporated by heat, the Epsom salt was separated from the gvpsum by water. The result of these trials is expressed in the following table. Dry gypsum. Dry Epsom salt. 5 gr. of limestone from Breedon gave 3.9 3.15 Matlock 3.95 2.9 Worksop 3.8 3.0 York 3.8 3.1 3 gr. of calcareous spar and 1 gr. of calcined magnesia gave 3.9 2. 7 As the preceding method of estimating the quantities of magnesia and calcareous earth is liable to considerable error, I afterwards examined them in the following manner, which seems capable of great exactness. Twenty-five grains of each sub- stance were dissolved by marine acid, in a cup of platina, and after the solution was evaporated to dryness, it was made red-hot for a few minutes. The mass re- maining in the cup, which consisted of muriated lime, and of the magnesia freed from the acid, was washed out with water, and poured into a phial. There was then added to it a known quantity of diluted marine acid, somewhat more than was sufficient to re-dissolve the magnesia, and, after the solution, a certain weight of calcareous spar, part of which would be dissolved by the superfluous acid. By the quantity of spar remaining undissolved, it was learnt how much acid was required to dissolve the magnesia. The iron and argillaceous earth contained in some speci- mens, were precipitated by the spar, and therefore could not occasion any error. TOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 553 The calcareous spar however dissolved more slowly where there was argillaceous earth, as it became coated with it; but this incrustation was occasionally removed, and, in all the experiments, the spar was left in the solution till it suffered no further diminu- tion. For this purpose it was necessary to keep them slightly warm for some days, during which time the phials were generally closed, to prevent any escape of the acid. The first experiment in the following table was made on known quantities of magnesia and calcareous earth, to try the accuracy of the process. For this pur- pose also, the 2d was repeated on a piece of limestone, previously powdered, to render every part of it of the same quality. The first column shows the quantity of calcareous spar which might have been dissolved by the acid required to take up the magnesia. The 2d shows the corresponding quantities of magnesia in 25 gr. of each substance. The 3d expresses the quantity of lime. This was inferred by subtracting the weight of the magnesia, and of the iron and clay, from 13.2 gr., the weight of the whole quantity of earth in 25 gr. of limestone. This is pro- bably not very incorrect, as, in 2 specimens which differed most in the proportion of magnesia and lime, the weight of the 2 earths was nearly the same. A piece of Dolomite, from Rome, was wrapped in a thin leaf of platina, that no part of it might be lost, and, being then exposed to a strongheat, left of earth 52.Q per cent. Dolomite from Mount Vesuvius 52.8 Breedon limestone 52.4 Calcareous spar left of lime 55.8 In 3 of the experiments also the calcareous earth was precipitated by mineral al- kali ; and the quantity of it being tried by that of the marine acid required to dissolve it, it corresponded very nearly with that set down. A quantity of marine acid which would dissolve 15 gr. of calcareous spar, would also dissolve 5.5 of cal- cined magnesia, and 2.5 gr. of spar; so that, 12.5 gr. of spar required the same quantity of acid as 5.5 gr. of magnesia. The magnesia used was very pure, and made red-hot immediately before it was weighed. Substances examined. Mixture of 5.5 gr. of magnesia and 14 gr. of calcareous spar 25 gr. of Breedon limestone, previously powdered , 25 gr. from part of the same powder , 25 gr. of Dolomite from Rome Dolomite from Iona Vesuvian Dolomite A 2d experiment, from part of the same Vesuvian Dolomite . . 25 gr. of magnesian limestone fromWansworth, nearDoncaster Thorpe arch Matlock ■ York Minster ■ Worksop Sherborn — — Westminster-hall VOL. XVIII. 4 B Quantity of spar which the acid, re- quired to Quantity of Quantity Iron and clay. take up the magnesia. of lime. magnesia, would have dissolved. 12.5 5.5 7 8 .0 11.53 5.071 7.929 .2 11.56 5.082 7913 .2 12.2 5.37 773 .1 10.1 44 7.8 1.0 10.38 4.565 8.575 .06 10.03 4.411 8.849 .06 12.75 5.61 7.34 .25 10.05 4.84 7-8 .6 12.5 5.5 7.388 .31 11. 4.84 8.26 J 11.6 5.104 7496 .6 11.5 5.08 7.56 .56 10.1 4.44 8.37 .4 I 111 554 PHILOSOPHICAL TRANSACTIONS. [ANNO 179Q. XVIII. Experiments and Observations on Shell and Bone. By Charles Hatcheit, Esq.F.R.S. p. 315. When shells were examined, they were immersed in acetous acid, or nitric acid diluted, according to circumstances, with 4, 5, 6, or more parts of distilled water ; and the solution was always made without heat. The carbonate of lime was preci- pitated by carbonate of ammonia, or of potash ; and phosphate of lime, if present, was previously precipitated by pure or caustic ammonia. If any other phosphate, like that of soda, was suspected, it was discovered by solution of acetite of lead. Bones and teeth were also subjected to the action of the acetous, or diluted nitric and muriatic acids. The dissolved portion was examined by the above-mentioned precipitants ; and, in experiments where the quantity of the substance would per- mit, the phosphoric acid was also separated by nitric or sulphuric acid. The phosphoric acid thus obtained, was proved, after concentration, by experiments which, being usually employed for such purposes, are too well known to require description. It is necessary moreover to observe, that as the substances examined were very numerous, and my principal object was to discover the most prominent characters in them, I did not, for the present, attempt in general to ascertain minutely the proportions, so much as the number and quality, of their respective ingredients. The greater part, if not all, of marine shells, appear to be of 2 descriptions, in respect to the substance of which they are composed. Those which will be first noticed, have a porcellaneous aspect, with an enamelled surface, and when broken are often in a slight degree of a fibrous texture. The shells of .the other division have generally, if not always, a strong epidermis, under which is the shell, princi- pally or entirely composed of the substance called nacre, or mother of pearl. Of the porcellaneous shells, various species of voluta, cypraea, and others of a similar na- ture, were examined. Of the shells composed of nacre or mother of pearl, I selected the oyster, the river muscle, the haliotis iris, and the turbo olearius. Experiments on porcellaneous shells. — Shells of this description, when exposed to a red heat in a crucible, about a quarter of an hour, crackled and lost the colours of their enamelled surface ; they did not emit any apparent smoke, nor any smell like that of burnt horn or cartilage. Their figure remained unchanged, excepting a few flaws ; and they became of an opaque white, tinged partially with pale gray, but retained part of their original gloss. The shells which had not been exposed to fire, whether entire or in powder, dissolved with great effervescence in the various acids; and the solution afterwards remained colourless and transparent. But the shells which had been burned, on being dissolved, deposited a very small quantity of animal coal ; by which the presence of some gluten was denoted, though the proportion was too small to be discovered in the solution of the shells which had not been burned. The various solutions were filtrated, and were examined by pure ammonia and acetite of lead ; but I never obtained any trace of phosphate of lime, VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 555 nor of any other combination of phosphoric acid. The carbonate of lime was after- wards precipitated by carbonate of ammonia ; and from many experiments it ap- peared, that porcellaneous shells consist of carbonate of lime, cemented by a very small portion of animal gluten. Previous to the experiments on shells composed of nacre or mother of pearl, I examined some patellae from Madeira. When these were exposed to a red heat in a crucible, there was a perceptible smell, like that of horn, hair, or feathers. The proportion of carbonic matter deposited by the subsequent solution, was more con- siderable than that of the shells above-mentioned ; and the proportion of carbonate of lime, relative to their weight, was less. When the recent shells were immersed in very dilute nitric acid, the epidermis was separated, the whole of the carbonate of lime was dissolved, and a gelatinous substance, nearly liquid, remained ; but without retaining the figure of the shell, and without any fibrous appearance. These shells evidently therefore contain a larger proportion of a more viscid gelatinous substance than those before mentioned ; but the solution, separated from the gela- tinous substance, afforded nothing but carbonate of lime. Experiments on shells composed of nacre, or mother of pearl.- — When the shell of the common oyster was exposed to a red heat, the effects were the same as those observed in the patellae, and the solution of the unburnt shell was similar, only the gelatinous part was rather of a greater consistency. A species of the river muscle was next subjected to experiment. This, when burned in a crucible, emitted much smoke, with a strong smell of burnt cartilage or horn ; the shell throughout be- came of a dark gray, and exfoliated. By solution in the acids, a large quantity of carbonic matter was separated ; and much less of carbonate of lime was obtained, from a given weight of the shell, than from those already mentioned. On im- mersing an unburnt shell in dilute nitric acid, a rapid solution and effervescence at first took place, but gradually became less, so that the disengagement of the car- bonic acid gas was to be perceived only at intervals. At the end of 2 days, I found nearly the whole of the carbonate of lime dissolved ; but a series of membranes, re- taining the figure of the shell, remained, of which the epidermis constituted the first. In the beginning, the carbonate of lime was readily dissolved, because the acid menstruum had an easy access ; but after this, it had more difficulty to insinuate itself between the different membranes, and of course the solution of the carbonate of lime was slower. During the solution, the carbonic acid gas was entangled, and retained in many places between the membranes, so as to give to the whole a cellular appearance. The haliotis iris, and the turbo olearius, resembled this muscle, excepting that their membranaceous parts were more compact and dense. These shells, when de- prived by an acid menstruum of their hardening substance, or carbonate of lime, appear to be formed of various membranes, applied stratum super stratum. Each membrane has a corresponding coat or crust of carbonate of lime ; which is so situated, that it is always between every 2 membranes, beginning with the epidermis, 4b 2 556 PHILOSOPHICAL TRANSACTIONS. [ANNO 1 7Q9» and ending with the last formed internal membrane. The animals which inhabit these stratified shells, increase their habitation by the addition of a stratum of car- bonate of lime, secured by a new membrane ; and as every additional stratum ex- ceeds in extent that which was previously formed, the shell becomes stronger n proportion as it is enlarged ; and the growth and age of the animal become denoted by the number of the strata which concur to form the shell. Though the haliotis iris and the turbo olearius are composed of the true mother of pearl, I was induced to repeat the foregoing experiments on some detached pieces of mother of pearl, such as are brought from China. These experiments I need not describe, as the results were precisely the same. I must however observe, that the membranaceous or cartilaginous parts of these shells, as well as of the pieces of mother of pearl, retained the exact figure of the shell, or piece, which had been immersed in the acid menstruum ; and these membranaceous parts distinctly ap- peared to be composed of fibres placed in a parallel direction, corresponding to the configuration of the shell. The same experiments were made on pearls ; which proved to be similar in composition to the mother of pearl ; and, so far as their size would enable me to discern, they appeared to be formed by concentric coats of membrane and carbonate of lime ; by this structure they much resemble the glo bular calcareous concretions, found at Carlsbad and other places, called pisolithes. The wavy appearance and iridescency of mother of pearl, and of pearl, are evidently the effect of their lamellated structure and semi-transparency ; in which, in some degree, they are resembled by the lamellated stone called adularia. When the experiments on the porcellaneous shells, and on those formed of mother of pearl are compared, it appears that the porcellaneous shells are composed of carbonate of lime, cemented by a very small portion of gluten ; and that mother of pearl and pearl do not differ from these, except by a smaller proportion of car- bonate of lime ; which, instead of being simply cemented by animal gluten, is in- termixed with, and serves to harden, a membranaceous or cartilaginous substance ; and this substance, even when deprived of the carbonate of lime, still retains the figure of the shell. But between these extremes there will probably be found many gradations ; and these we have the greater reason to expect, from the example afforded by the patellae, which have been lately mentioned. Some few experiments were made on certain land shells ; and in the common garden snail I thought that I discovered some traces of phosphate of lime ; but, as I did not find any in the helix nemoralis, it may be doubted whether the presence of phosphate of lime should be considered as a chemical character of land shells.* Experiments on the covering substance of crust aceous marine animals. <\ — As I was * Some experiments which I have lately made on the cuttle-bone of the shops, have proved, that the term bone is here misapplied, if the presence of phosphate of lime is to be regarded as the characteristic of bone ; for this substance, in composition, is exactly similar to shell, and consists of various mem- branes hardened by carbonate of lime, without the smallest mixture of phosphate. f Under this head 1 have included my experiments on echini, star-fish, crabs, lobsters, &c. — Orig. VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 557 not acquainted with any experiments by which the chemical nature of the substance which covers crustaceous marine animals had been determined, I was desirous to ascertain in what respect it was different from shell, and I began these experiments on 3 species of the echinus, with which I had been favoured by the Right Hon. President. I was the more inclined to begin with the echini, because naturalists do not appear to be perfectly agreed, whether to call them testaceous or crustaceous animals. Klein, who has written a work on echini, after having noticed the various opinions of Rondelet, Rumphius, and others, determines that they are to be re- garded as testaceous animals. But Linnaeus was of the contrary opinion, as appears from his definition of the echinus. " Corpus subrotundum, crusta ossea tectum, spinis mobilibus saepius asperum." Now, as the experiments above related had proved, that the shells of marine animals were composed of carbonate of lime, without any phosphate, I thought it very possible, that the covering of the crustaceous animals might, in some respect, be different, and if so, I should thus, by chemical characters, be enabled to ascer- tain the class to which the echinus was to be referred. Of the 3 echini which were examined, one had small spines; the 2d had large obtuse spines; and the 3d was of a very flat form. Portions of these echini were separately immersed in acetous, muriatic, and diluted nitric acid, by each of which they were completely dissolved, with much effervescence ; depositing, at the same time, a thin outer skin or epi- dermis. The transparency of the solutions was also disturbed by a portion of gluten, which remained suspended, and communicated a brownish colour to the liquors. The solutions in acetous and diluted nitric acid were filtrated; after which, from the acetous solution of each echinus, I obtained a precipitate of phosphate of lead, by the addition of acetite of lead ; and, having thus proved the presence of phosphoric acid, I saturated the nitric solutions with pure ammonia, by which a quantity of phosphate of lime was obtained, much inferior however in quantity, to the carbonate of lime, which was afterwards precipitated by carbonate of ammonia. The com- position of the crust of the echinus is therefore different from that of marine shells ; and, by the relative proportions and nature of the ingredients, it approaches most nearly to the shells of the eggs of birds ; which, in like manner, consist of car- bonate, with a small proportion of phosphate of lime, cemented by gluten. It remained now to examine the composition of those substances which are de- cidedly called crustaceous ; but previous to this, some experiments were made on the asterias or star-fish, of which I took the species commonly found on our coasts, and known by the popular name of five fingers, asterias rubens. The asterias is thus described by Linnaeus. " Corpus depressum, subtus sulcatum: crusta coriacea, tentaculis muricata." When the asterias was immersed in the acids, a considerable effervescence was produced, and a thin external stratum was dissolved ; after which it remained in a perfectly coriaceous state, and complete, in respect to the original figure. The dissolved portion, being examined by the usual precipitants, proved to be carbonate of lime, without any mixture of phosphate ; but in another species 558 PHILOSOPHICAL TRANSACTIONS. [ANNO 17 QQ. of the asterias, which had 12 rays, asterias papposa, I discovered a small quantity of phosphate of lime, I am therefore induced to suspect that, in the different species of the asterias, nature makes an imperfect attempt to form shell on some and a crustaceous coating on others; and that a series of gradations is thus formed between the testaceous, the crustaceous, and the coriaceous marine animals. It was now requisite to ascertain if phosphate of lime is a component part of the substance which covers the crustaceous marine or aquatic animals, such as the crab, lobster, prawn, and crayfish. Pieces of this substance, taken from various parts of those animals, was at different times immersed in acetous, and in diluted nitric acid; those which had been placed in the diluted nitric acid, produced a moderate effervescence, and in a short time were found to be soft and elastic, of a yellowish - white colour, and like a cartilage which retained the original figure. The same effects were produced by acetous acid, but in a less degree; in the latter case also the colouring matter remained, and was soluble in alcohol. All the solutions, both acetous and nitric, afforded carbonate and phosphate of lime, though the former in the larger proportion. There is reason to conclude therefore, that phosphate of lime, mingled with the carbonate, is a chemical characteristic which distinguishes the crustaceous from the testaceous substances; and that the principal difference in the qualities of each, when complete, is caused by the proportion of the hard- ening substances, relative to the gluten, by which they are cemented; or by the abundance and consistency of the gelatinous, membranaceous, or cartilaginous substance, in and on which, the carbonate of lime, or the mixture of carbonate and phosphate of lime, has been secreted and deposited. And, as the presence of phosphate of lime, mingled with carbonate appears to be a chemical character of crustaceous marine animals, there is every reason to conclude that Linnaeus did right not to place the echini among the testaceous ones. The presence of phosphate of lime, in the substance which covers the crusta- ceous marine animals, appears to denote an approximation to the nature of bone, which, not only by the experiments of Mr. Gahn, but by the united testimony of all chemists, has been proved principally to consist, as far as the ossifying substance is concerned, of phosphate of lime. This consideration therefore induced me to repeat the above experiments, on the bones of various animals. It is scarcely necessary to mention the usual effects of acids on bones steeped in them, as they are known to every physiologist and anatomist. In every operation of this nature, the ossifying substance, which is principally phosphate of lime, is dissolved, and a cartilage or membrane, of the figure of the original bone, remains; so that the first origin of bones appears to be by the formation of a membrane or cartilage, of the requisite figure, which, when the subsequent secretion of the ossifying sub- stance takes place, is penetrated by it, and thus becomes more or less converted into the state of bone. It is also known, that the nature of the bone is more influenced by the greater or less predominance of the membranaceous or cartilagi- nous part, than by any other cause. It is not therefore for me to add any thing to VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 559 this part; and in respect to the substance which is the cause of ossification, little also requires to be mentioned, for this, as before observed, is known principally to consist of phosphate of lime. I shall only therefore briefly mention the results of certain experiments. The bones of fish, such as those of the salmon, mackerel, brill, and skate, afforded phosphate of lime; and the only difference was, that the bones of these fish appeared in general to contain more of the cartilaginous substance, relative to the phosphate of lime, than is commonly found in the bones of quadrupeds, &c. The different bones also of the same fish were various in this respect; and the bones about the head of the skate only differed from cartilage, by containing a moderate proportion of phosphate of lime. It is at present believed that phos- phate, with some sulphate of lime, constitutes the whole of the ossifying sub- stance; and perhaps the formation of bone from cartilage depends only on the phosphate of lime; but whether this is the case or not, it is fit that I should notice a 3d substance, which constantly occurred in the course of my experiments. When human bones, or teeth, as well as those of quadrupeds and fish, whether recent or calcined, were exposed to the action of acids, an effervescence, though at times but feeble, was produced. This circumstance at first I did not particularly notice, but the following experiments excited my attention. After the phosphate of lime had been precipitated from the solutions of various teeth and bones, by pure ammonia, I observed that a 2d precipitate, much smaller in quantity, was obtained by the addition of carbonate of ammonia. This 2d precipitate dissolved in acids, with much effervescence, during which carbonic acid was disengaged; and selenite was formed by adding sulphuric acid. The solution of this precipitate did not contain any phosphoric acid; nor did the liquor from which the precipitate had been separated afford any trace of it. This precipitate was therefore carbonate of lime; but I still was not certain that it existed, as such, in the teeth and bones. Though regular and comparative analyses of the bones of different animals have not hitherto been made, yet, by the experiments of Messrs. Gahn, Scheele, Macquer, Fourcroy, Berniard, and the Marquis de Bullion, it has been proved, that phosphate of lime is the principal ossifying substance of bones in general, and that this is accompanied by a small proportion of some saline substances, and by sulphate of lime. I was therefore desirous to ascertain, whether the carbonate of lime, which I had obtained by the above-mentioned experiments, had been pro- duced from the sulphate of lime decomposed by the alkaline precipitant, or whe- ther the greater part had not existed in the bones, in the state of carbonate. Each of the solutions in nitric acid afforded a precipitate with nitrate of barytes; but the quantity of sulphuric acid thus separated, appeared by far too small to be capable of saturating the whole of the carbonate of lime obtained from an equal quantity of the solution. To prove therefore the presence of the carbonic acid, and the consequent formation of carbonate of lime, portions of the various teeth and bones were immersed, at separate times, in muriatic acid; and the gas produced 558 PHILOSOPHICAL TRANSACTIONS. [ANNO 1790. was received in lime-water, by which it was speedily absorbed, and a proportionate quantity of carbonate of lime was obtained. Though it appears, that the prin- cipal effects during ossification are produced by phosphate of lime, yet we here see, that not only sulphate, but also some carbonate of lime, enters the composition of bones; and it is not a little curious to observe, that as the carbonate of lime exceeds in quantity the phosphate of lime in crustaceous marine animals, and in the egg shells of birds, so in bones it is vice versa. It is possible, when many accurate comparative analyses of bones have been made, that some may be found composed only of phosphate of lime; and that thus, shells containing only car- bonate of lime, and bones containing only phosphate of lime, will form the 2 extremities of the chain. I shall now make a few remarks on the enamel of teeth. When a tooth coated with enamel is immersed in diluted nitric or muriatic acid, a feeble effervescence takes place, and the enamel is completely dissolved; so also is the bony part, but the cartilage of that part is left, retaining the shape of the tooth. Or, if a tooth in which the enamel is intermixed with the bony substance, is plunged in the acid, the enamel and ihe bony part are dissolved, in the same manner as before; that is to say, the enamel is completely taken up by the acid, while the tooth, like other bones, remains in a pulpy or cartilaginous state, having been deprived of the ossi- fying substance. Consequently, those parts which were coated or penetrated by lines of enamel, are diminished in proportion to the thickness of the enamel which has been thus dissolved; but little or no diminution is observed in the tooth.* Mr. Hunter has noticed this; and, speaking of enamel, says, " when soaked in a gentle acid, there appears no gristly or fleshy part with which the earthy part had been incorporated. "-j~ Now, when the difference which has been lately stated, between porcellaneous shell and mother of pearl, is considered, it is not possible to avoid the comparing of these to enamel and tooth. When porcellaneous shell, whole or in powder, is exposed to the action of acids, it is completely dissolved, without leaving any residuum. Enamel is also completely dissolved, in the like manner. Porcellaneous shell and enamel, when burnt, emit little or no smoke, nor scarcely any smell of burnt horn, or cartilage. Their figure, after having been exposed to fire, is not mate- rially changed, except by cracking in some parts: their external gloss partly remains, and their colour at most becomes gray, very different from what happens to mother of pearl, or tooth. In their fracture they have a fibrous texture; and in short the only essential difference between them appears to be, that porcella- neous shell consists of carbonate of lime, and enamel of phosphate of lime, each being cemented by a small portion of gluten. * I have also observed, that when raspings of enamel are put into diluted nitric or muriatic acid, they are dissolved without any apparent residuum j but when raspings of tooth or bone are thus treated, portions of membrane or cartilage remain, corresponding to the size of the raspings. + Nat. Hist of the Human Teeth, p. 35. — Orig. VOL. LXXXIX.] PHILOSOPHICAL TRANSACTION'S. 56l In like manner, if the effects produced by fire and acid menstrua, on shells composed of mother of pearl, and on the substance of teeth and bone, are com- pared, a great similarity will be found; for, when exposed to a red heat, 1°. They smoke much, and emit a smell of burnt cartilage, or horn. 2°. They become of a dark grey or black colour. 3°. The animal coal thus formed is of difficult incinera- tion. 4°. They retain much of their original figure; but the membranaceous shells are subject to exfoliate.* 5°. These substances, pearl, mother of pearl, tooth, and bone, when immersed in certain acids, part with their hardening or ossifying substances, and then remain in the state of membrane or cartilage. 6°. When previously burned, and afterwards dissolved in acids, a quantity of animal coal is separated, according to the proportion of the gelatinous, membranaceous, or cartilaginous substance, and according to the duration of the red heat. And lastly, the acid solutions of these substances, by proper precipitants, afford carbo- nate of lime, in the one case, and phosphate of lime principally, in the other, in a proportion relative to the membrane or cartilage with which, or on which, the one or the other had been mixed, or deposited. As porcellaneous shell principally differs from mother of pearl, only by a relative proportion between the carbonate of lime and the gluten or membrane, in like manner, the enamel appears only to be different from tooth or bone, by being destitute of cartilage, and by being principally formed of phosphate of lime, cemented by gluten. The difference, in the latter case, seems to explain why the bones and teeth of animals fed on madder become red, when, at the same time, the like colour is not communicated to the enamel; for it appears probable, that the cartilages which form the original structure of the teeth and bones, become the channels by which the tinging principle is communicated and diffused. These comparative experiments prove, that there is a great approximation in the nature of porcellaneous shell and the enamel of teeth, and also in that of mother of pearl and bone; and if a shell should be found composed of mother of pearl coated by the porcellaneous substance, it will resemble a tooth coated by the enamel, with the difference of carbonate being substituted for phosphate of lime. Some experiments on cartilaginous substances have in a great measure convinced me, that membranes and cartilages (whether destined to become bones by a natural process, as in young animals, or whether they become such by morbid ossification, as often happens in those which are aged), do not contain the ossifying substance, or phosphate of lime, as a constituent principle. I mean by this, that I believe the portion of phosphate of lime found in cartilaginous and' horny sub- stances to be simply mixed as an extraneous matter; and that when it is absent, mem- brane, cartilage, and horn, are most perfect and complete. The frequent presence of phosphate of lime in cartilaginous substances, is not a proof of its being 1 of their constituent principles, but only that it has become deposited and mixed with them, in proportion to the tendency they may have to form modifications of bone; or * This is a natural consequence, arising from their structure. — Orig. VOL. XVIII, 4 C 562 PHILOSOPHICAL TRANSACTIONS. [ANNO 1709. according to their vicinity with such membranes or cartilages as are liable to such a change. If horns are examined, few I believe will be found to contain phos- phate of lime in such a proportion as to be considered an essential ingredient. I would not be understood to speak here of such as stag or buck horn, for that has every chemical character of bone, with some excess of cartilage; but I allude to those in which the substance of the horn is distinctly separate from the bone, and which, like a sheath, covers a bony protuberance which issues from the os frontis of certain animals.* Horns of this nature, such as those of the ox, the ram, and the chamois, also tortoise shell, afford, after distillation and incineration, so very small a residuum, of which only a small part is phosphate of lime, that this latter can scarcely be re- garded as a necessary ingredient. By some experiments made on 500 gr. of the horn of the ox, I obtained, after a long continued heat, only 1.50 gr. of residuum; and of this, less than half proved to be phosphate of lime. 78 gr. of the horn of the chamois afforded only 0.50 of residuum ; and 500 gr. of tortoise shell yielded not more than 0.25 of a gr., of which, less than half was phosphate of lime. Now it must be evident, that so very small a quantity cannot influence the nature of the substances which afforded it ; and the same may be said of synovia, 480 gr. of which did not yield more than 1 gr. of phosphate of lime. This substance is undoubtedly various in its proportions, in all these and other animal substances, arising probably from the age and habit of the animal which has produced them ; but I believe that I may, at least, venture to place some confidence in the fore- going experiments, as several others, made since the above was written, have tended to confirm them. -J- In the course of making the experiments which have been related, I examined the fossil bones of Gibraltar, as well as some glossopetrae or shark's teeth. The latter afforded phosphate and carbonate of lime ; but the carbonate of lime was visibly owing principally to the matter of the calcareous strata which had inclosed these teeth, and which had insinuated itself into the cavities left by the decomposi- tion of the original cartilaginous substance. The bones of the Gibraltar rock also consist principally of phosphate of lime; and the cavities have been partly filled by the carbonate of lime which cements them together. Fossil bones resemble bones which, by combustion, have been deprived of their cartilaginous part; for they retain the figure of the original bone, without being bone in reality, as one of the * Nature seems here to have made an analysis or separation of horn from bone. — Orig. ■f These experiments were repeated on bladder, which I chose in preference to any other membrane, as not being liable to ossification, and therefore likely to contain very little or no phosphate of lime. 250 gr. of dry hogs' bladder, after incineration, left a residuum the weight of which did not exceed J^j of a gr. This was dissolved in diluted nitric acid ; and, on adding pure ammonia, some faint traces of phosphate of lime were observed. Now as 250 gr. of bladder did not afford more than -^ of a gr. of residuum, of which only a part consisted of phosphate of lime, there is much reason to regard thig experiment as an additional proof, that phosphate of lime is not an essential ingredient of membrane. — Orig. VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 563 most essential parts has been taken away. Now such fossil or burnt bones can no more be regarded as bone, than charcoal can be considered as the vegetable of which it retains the figure and fibrous structure. Bones which keep their figure after combustion, resemble charcoal made from vegetables replete with fibre; and cartilaginous bones which lose their shape by the same cause, may be compared to succulent plants which are reduced in bulk and shape in a similar manner. From these last experiments, I much question if bodies consisting of phosphate of lime, like bones, have concurred materially to form strata of limestone or chalk; for it appears to be improbable that phosphate is converted into carbonate of lime, after these bodies have become extraneous fossils. The destruction or decomposition of the cartilaginous parts of teeth and bones in a fossil state, must have been the work of a very long period of time, unless accelerated by the action of some mineral principle; for after having, in the usual manner, steeped in muriatic acid the os humeri of a man brought from Hythe, in Kent, and said to have been taken from a Saxon tomb, I found the remaining cartilage nearly as complete as that of a recent bone. The difficult destructibility of substances of a somewhat similar nature, appears also from the mining implements formed of horn, which are not unfrequently found in excavations of high antiquity. XIX. A Catalogue of Oriental Manuscripts presented to the Royal Society by Sir PVm. and Lady Jones., By Charles Wilkins, Esq., F. R. S. p. 335. Continued from page 430 of this vol. SANSCRITA. 57. Gita and Dharmanusasana. Two extracts from the Maha-bharata, with beautiful drawings 3 written in the Devanagari character. S. W. J. 58. Raghuvansa. The Children of the Sun, a poem, by Calidas. Bengal character. S. W. J. 59- Prabodha Chandrodaya. The Rising Moon of Knowledge, a drama, by Cesava Misra. Bengal character. S. W. J. CHINESE. 60. Con Fu Tsu. The works of Confucius, vol. 2, 3, 4, 5, 6. S. W. J.* 61. Tahia Su Shuw. A commentary. S. W. J. 62. Shung Lon Su Shuw. A commentary. S. W. J. 63. Hor Lon Su Shuw. A commentary. S. W. J. 64. Shung Morng Su Shuw. A commentary. S. W. J. 65. Hor. Morng. Su Shuw. A commentary. S. W. J. 66. Shi Kin. A book of Chinese odes. Lr. J. 67. Lon Yu. A grammar of the Chinese Language. \J. J. 68. A dictionary. Chinese and Latin. I/. J. PERSIAN. 69. Zafar Nameh. A most elegant history of Taimur ; written in the Niskh character. I/. J. 70. Towarikh i Gujarat. A history of the province of Guzerat. I/. J. 71. Tarikh i Bahadershahi. A. history of the Emperor Bahader Shah. U. J. 72. Tarikh i Jenahcusha. The history of Nadir Shah, by Mirza Mahadi Khan. I/. J. 73. Narrative of the proceedings of Scindia, and the confederates. U. J. 74. Jehangir Nameh. The history of Jehangir Shah. I/. J. * From No. 60 to 67, inclusive, are printed from blocks. No. 68 is manuscript. — Orig. 4 c 2 5^4 PHILOSOPHICAL TRANSACTIONS. [ANNO 179Q. 75. Mujmel at Tarikh i Nadiri. An Abridgment of the History of Nadir Shah. I/. J. 76. History of Hindostan, by Gholam Hussain. S. W. J. 77. Behar i Danish. The tales of Inayetulla. If. J. 78. Bostan i Khyaal. The Garden of Imagination, an historical romance, in 8 vols. I/. J. 79- Jamay ul Hecayet. A collection of tales 3 written in the Niskh character. S. W. J. 80. a. Shah Nameh. The heroic poem of Ferdosi. I/. J. 80. b. Ditto. In 4 vols. S. W. J. 81. a. Masnavi. A poem, by Jalal ud Din, surnamed Rumi. I/. J. 81. b. Ditto. Six vols. S. W. J. 51. c. Ditto. First book only. I/. J. 8 1 . d. Ditto. A commentary on the first book. Ly. J. 81. e. Ditto. A commentary on the first book. Ly. J. 81. f. Ditto. A table of contents of the first book. Ly. J. 52. a. Culyat i Jami. The works of the poet Jami. S. W. J. 82. b. Ditto. The miscellaneous poems of Jami. I/. J. 83. Yusuf wa Zuleyca. A poem, by Jami. I/. J. 84. a. Culyat i Nizami. The works of the poet Nizami. S. W. J. 84. b. Ditto. The 5 poems of Nizami. Ly. J. 85. Culyat i Anwari. The works of the poet Anwari. S. W. J 86. Dewan i Khosru. The odes of Khosru. S. W. J. 87. Dewan i Saib. The odes of Saib. S. W. J. 8S. Dewan i Arfi. The odes of Arfi. S.W.J. 89. Dewan i Casim. The odes of Casim. V. J. 90. Dewan i Jami. The odes of Jami. 91. Asrar, or, Ishak Nameh. Secrets, or, the history of love : a poem. L\ J. 92. Miscellaneous Poems. Chiefly by Arfi. 93. Mujma uz Zaya. On the art of poetry. I/. J. 94. Mekhzen i Asrar. The treasury of secrets : a poem, by Nizami. I/. J. 95. Dewan i Catibi. A book of Odes. L\ J. 96. A poem, by Jami. Imperfect. U. J. 97. Miscellaneous, prose and verse. By Arfi, and others. S. W. J. 98. Sharah i Khajah Hafiz. A commentary on the odes of Hafiz. U. J. 99. Silsilat uz Zahib. The chain of gold : a poem, by Jami. U. J. 100. Pand Namah. Moral sentences, in verse, by Farid ud Din Attar. I/. J. 101. Baharam and Gulandam. A love tale, by Catabi. V. J. 102. Fahrang i Jehangiri. A dictionary of the Persian language by Jamal ud Din Husain Anju. Complete. I/. J. - 103. The Grammatical Introduction to the Farhang i Jehangiri. Ly. J. 104- Fowayed i Ghaniya. A short treatise on Persian and Hindu grammar. Ly. J. 105. A dictionary of the Persian language. No title. I/. J. 106. Tohfit ul Hind. A miscellaneous treatise on the literature, &c. of the Hindus. Enriched with marginal notes by Sir W. J. S. W. J. 107. a. Sri Bhagavata. A translation of N° 3. I/. J. 107. b. Ditto. With drawings. Ly. J. 108. Ramayana. A translation of N° 2. V.J. 109. Anwari Soheili. A Persian version of the Hitopadesa, by Husain Vaiz, surnamed Cashifi. 1 10. Arjuna Gita. Translation of the Gita. I/. J. 111. Siva Purana. Translation from the Sanscrita. Ly. J. 112. Raga Darpana. A treatise on Hindu music. Translated from the Sanscrita. Ly. J. 113. Parijataka. A treatise on Hindu music. Translated from the Sanscrita, by Roshin Zamir,. in the reign of Aurungzeb. Ly. J. 114. Hazar Dharpad. A treatise on vocal music, according to the Hindus. Ly. J. / VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 505 115. Shams ul aswat. The sun of sounds. A treatise on Hindu music. U.J-. 116. Cefayet ut Talim. A treatise on astronomy, by Mahommed, son of Masawad Mahommed. V. J 1 17. Lowaih ul Kamar. A treatise on astronomy. Ly. J. 118. Resalah Sharifah. A treatise on astronomy. Ly. J. 119. A treatise on astronomy, with tables, in the Niskh character. I/. J. 120. Sharah i Zij i Merza Ulagh Beg. A commentary on the tables of Ulagh Beg. Ly. J. 121. Sharah i Elm i Hay at. A commentary on the science of astronomy. I/. J. 122. Miscellaneous loose sheets on astronomy. Ly. J. 123. Tala Nameh and Sharah Tala. Two treatises on fortune-telling. I/. J. 124. Five tracts on geometry. I/. J. 125. Ferayez i Mahommedi. 126. Sharah i Burdah. A commentary on the poems called Burdah. I/. J. 127. Mirat ul Misayeb i Mahommed Shahi. Expositions of matters of faith and jurisprudence, com- piled for the use of Mahommed Shah. I/. J. 128. Myrat ul Hakayak I/. J. 129. Sharif iyah. A comment on the Sirajiyahof Alsayad, translated from the Arabic, by Mahommed Kasin. I/. J. 130. Forms of oaths held binding by the Hindus, by Ali Ibrahim Khan, chief magistrate at Benarig. 17. J. 131. Jama Abasi, on Mahommedan duties. Lv. J. 132. Tohfit ul Momenain. A dictionary of natural history. Ly. J. 133. Tarjama i Ferayez i Sirajiyah ba Fowayed i Sharifiyah. A translation of two works in Arabic, on Mahommedan duties. Ly. J. 134. Resalah i Mofazzel. A translation from an Arabic treatise, by Mahommed Baker. 135. Kitab ul Biyua. A law tract, translated from the Arabic. U. J. 136. Miscellaneous fragments. ARABIC. 137. a. Al Kuduri. Institutes of Mahommedan law, by Abul Hasan A'hmed, of Bagdad, surnamed Al Kuduri, of which the Hadayah is a comment. I/. J. 137. b. Ditto. I/. J. 138. Hedayah. A comment on Al Kuduri, by Burhan ud Din ul Marghinani. I/. J. 139. Fatavi Alemgiri. Decisions collected by order of the Emperor Aurungzeb. Four vols. I/. J. 140. Al Sharifiyah. A commentary on a law book, called Al Sarajiyah, by Sayad Sharif. I/. J. 141. Mazheb ul Imam ul Aazem Abu Hanifeh. The religious doctrines and opinions of Abu Hanifeh. Ly. J. 142. Cashcul. An Asiatic miscellany, by Buha ud Din al Aamili. I/. J. 143. Sacardan us Sultan. A treatise on various mystical subjects, in 7 chapters, by Shekh Ibn i Hajalah. I/. J. 144. Al Cafiyah. A grammar of the Arabic language, by Ibn ul Hajib 5 with a commentary, by Mula J ami. I/. J. 145. a. Kamus. A dictionary of the Arabic language. S. W. J. 145. b. Ditto. Ly. J. 146. Al Khulaset. A grammar of the Arabic language. I/. J. 147. Two treatises on Arabic grammar. I/. J. 148. A treatise on Arabic grammar. Ly. J. 149. A dictionary of the Arabic language. 17. J. 150. Elm i Hindisa. A treatise on geometry, by Bu Ali Sena. I/. J. 151. A treatise on geometry, with tables. 152. Al Mutalab ul Hasani. Propositions in theology. I/. J. 153. Hamasah. Ancient Arabian poems, collected by Abu Tt'mmam. Copied from a manuscript traced on oiled paper. S. W. J. 566 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. 154. Al Motanabi. The poems of AbuTaib, surnamed Al Motanabi. S. W. J. 155. Dewan i Ali. The poems of Ali. S. W J. 156. Dewan ul A'shak. A book of poems. S.W.J. 157. Sharah i akayad i Mula Saduddin. A commentary on the Akayad, by Saduddin. S. W. J. 158. Sharah ul Moalakat. A commentary on the Moalakat. I/. J. 159. Sharah ul Mobarak. Another commentary on the Moalakat. I/. J. 160. Kasayed sabah moalakah. The poems of Almutalammis. I/. J. 16*1. Kasayedul Musabba. Poems. I/. J. 162. A'dabul Maluk. The manners of princes. L\ J. 163. Behr ul Bask. I/. J. 164. TaifulKhiyal. S.W.J. 165. Moruj uz zeheb wa maaden ul Joher. An historical and geographical work, by Abul Hassan, surnamed Masaudi. S. W. J. 166. Hariri. The moral discourses of Hariri. S. W. J. 167. An Arabic manuscript, traced on oiled paper. Probably that copy of the ancient Arabian poems, called Hamasah, mentioned N° 1 53. I/. J. 168. A new copy of a manuscript, in sheets. No name. Ly. J. HINDOSTANI. 169. Gulistan. Translated from the Persian. S. W. J. 170. A commentary on the Grunt'ha, the religious institution of the Sic'hs, in the Nagari cha- racter. 17. J. END OF THE EIGHTY-NINTH VOLUME OP THE ORIGINAL. I, The Croonian Lecture. On the Structure and Uses of the Membrana Tympani of the Ear. By Everard Home, Esq. F. R. S. Anno 1800. Vol. XC. p. 1. The principal object of the present lecture is to communicate a discovery of the structure of the membrana tympani ; which, in some respects, affords a new and very curious instance of the application of muscular action, and may conduce to ac- count for certain phenomena in the sense of hearing, in a more satisfactory manner than has hitherto been proposed. The membrana tympani has always been con- sidered as a common membrane, which, by means of muscles belonging to the malleus being stretched or relaxed, became fitted, in its various degrees of tension, to convey the vast variety of external sounds to the internal organ. Its shape, situation, and office, have procured it the name of drum of the ear; and the muscles of the malleus having been deemed sufficient for bracing and unbracing it, less at- tention was bestowed on the structure of the membrane itself: to which may be added, that in the human ear, and generally in the ear of quadrupeds, the mem- brane is so extremely small and thin, and in its situation so peculiarly confined, as not to be got at for inspection but with much difficulty. The case is different in the elephant, where this membrane is so very large, that the parts of which it is composed are readily distinguished: they are even conspicuous to the naked eye; and muscular fibres are seen passing along the VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 567 membrane, in a radiated manner, from the bony rim which surrounds it, to- wards the handle of the malleus, to which the central part of the membrane is firmlv attached. This discovery in the elephant having led to that of a similar construction in the human membrana tympani, it may not be improper to relate the circumstances by which I became engaged in the investigation of the organ of hearing in that animal. Three different opportunities have occurred of dissecting the elephant in London, by the deaths of those which had been presented to his Majesty, and were kept at the King's stables at Pimlico. One of them was given to the late Dr. Hunter; one to his brother Mr. J. Hunter; and the third to Sir Ash ton Lever. From my being connected with Mr. J. Hunter's pursuits in comparative anatomy, I was employed throughout the whole of these dissections, and became extremely desirous of examining the internal parts of the ear, the structure of that organ in the human body having at a very early period particularly engaged my attention;* but neither Dr. Hunter nor his brother could be prevailed on to sacrifice so large a portion of the skull as was necessary for the purpose. When Mr. Corse arrived from Bengal, last year, and mentioned his having brought over a number of skulls of elephants, in order to show the progress of the formation of their grinding teeth,-f- the desire to examine the organ of hearing in that animal recurred to me so strongly, that I requested to have one of the skulls for that purpose, and Mr. Corse very readily and obligingly complied with my request. After having examined the organ in the dried skull, the want of the membrana tympani, and of the small bones, made the information thus received of a very unsatisfactory nature, and increased trfe desire of seeing these parts in the recent head. In considering how this could be done, I recollected a mutilated elephant's head, preserved in spirits, which had been sent to Mr. Hunter; but which, from the multiplicity of his engagements had remained neglected in the cask at the time of his death, and in the following year was dried, to show the proboscis, that it might not be altogether spoiled. On examining this dried head, the bones had been so much broken, that one of the organs of hearing was altogether wanting; the other however was fortunately entire; and the membrana tympani and small bones, having been little disturbed in the drying of the parts, remained nearly in their natural situation. The membrana tympani, and every other part of the organ, were found to be much larger in pro- portion than in other quadrupeds, or in man; differing in this respect from the eye * In 1776, I injected the cochlea and semicircular canals of the human ear with a composition of wax and rosin. This was done by placing the temporal bone in the receiver of an air-pump, the upper part of which was in the form of a funnel, rendered airtight by a cork being fitted into its neck, and surrounded with bees' wax. After the air had been exhausted, the hot injection, poured into the funnel, melted the wax, and the cork was pulled out by means of a string previously attached to it; the injec- tion immediately rushed into the receiver, and was forced, by the pressure of the atmosphere, into the cavities of the temporal bone. + On this subject, a very ingenious paper has been since published by him, in the Phil. Trans, for 1799.— Orig. 568 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. of the elephant, which is unusually small, when compared with the enormous bulk, of the animal. The membrane was found of an oval form; the short diameter of the oval rather more than an inch in length; the long diameter an inch and ^V» In the human ear, the membrana tympani is nearly circular; the longest diameter is ^ of an inch; the shortest ^V- As the membrane in the elephant exceeds that of the human ear in thickness as much as in extent, which is as the squares of their diameters, or in the proportion of 135 to 14, it is natural to conclude that the muscular fibres which are to stretch the one, must greatly exceed in strength those capable of producing the same degree of tension in the other. - From this statement, the muscular structure in the human membrana tympani will necessarily be so much less distinct than in the elephant, as scarcely to be visible to the naked eye, and will easily be overlooked by the most attentive observer, who is not directed by some previous information to examine it under the most favour- able circumstances; but when these are attended to, it can be perceived without the aid of glasses. If the membrana tympani of the human ear be completely exposed on both sides, by removing the contiguous parts, and the cuticular covering care- fully washed off from its external surface; then, by placing it in a clear light, the radiated direction of its fibres may be easily detected. If a common magnifying glass be used, they are rendered nearly as distinct as those of the elephant appear to the naked eye; their course is exactly the same; and they differ in nothing but in being formed on a smaller scale. When viewed in a microscope magnifying 23 times, the muscular fibres are beautifully conspicuous, and appear uniformly the same throughout the whole surface, there being no central tendons, as in the diaphragm; the muscular fibres appear only to form the internal layer of the mem- brane, and are most distinctly seen when viewed on that side. In examining this membrane in different subjects, the parts were frequently found in a more or less morbid state. In one instance the membrane was found loaded with blood-vessels, was less transparent than usual, and was united by close adhesion to the point of the long process of the incus. In another instance, there was a preternatural ossification adhering to it, at a small distance from the end of the handle of the malleus. As muscles in general are supplied with blood-vessels in proportion to the fre- quency of their action, it is an object of importance to determine the vascularity of the membrana tympani. On this subject my own want of information has been amply supplied by Dr. Baillie, who, in a communication on this subject, showed me a preparation of the membrane, in which the vessels had been most successfully injected with coloured wax. In this preparation, the most beautiful of the kind I ever saw, the vessels in their distribution resembled those of the iris, and were neaily half as numerous; they anastomosed with each other- in a similar manner, and their general direction was from the circumference to the handle of the malleus; from near this handle, a small trunk sent off branches, in a radiated manner, which anastomosed with those which had an opposite course. This correspondence, in VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 569 the number and distribution of blood-vessels, between the membrana tympani and the iris, is a strong circumstance in confirmation of that membrane being endowed with muscular action. In the horse, the membrana tympani is smaller than in man; its long diameter is -2V of an inch; the short one &\ and it is almost quite flat, while in man it is concave, which makes the difference of extent considerably exceed the difference in the diameters. In the horse, the fibrous structure is not visible to the naked eye; it is even indistinctly seen when viewed through a common magnifying glass; but in a microscope it is very visible, and in every other respect agrees in structure with the membrane in the human ear, and in that of the elephant. In birds, the membrana tympani is larger in proportion than in the quadruped, and more cir- cular in its shape. In the goose, it is ^%- of an inch in its longest diameter, and -gV in its shortest diameter. In the turkey -^ by ^. It is thinner in its coats in birds than in the horse, and to the naked eye has no appearance of fibres; but when viewed in a microscope, there is a visible radiated structure, not very unlike the wire marks on common writing paper. In a former Lecture on the Structure of Muscles #, in which a comprehensive view was taken of the subject, it was stated, that the organization necessary for muscular contraction could exist in an apparent membrane, and that a fasciculated structure was only necessary when muscular action was to be enabled to overcome resistance. The coats of the taenia hydatigena were mentioned as an instance of the first; and the human heart as the most complex of the 2d. In comparing the membranae tympani of different animals, they afford a beautiful illustration of the truth of this position. In birds, where from the smallness of its size the resistance is very trifling, the membrane is very similar to the coat of an hydatid, only still thinner. In the elephant, fibres forming fasciculi are very distinct. The mem- brane of the horse, and that of the human ear, form the intermediate gradations. The knowledge of a muscular structure in the membrana tympani, enables us to explain many phenomena in hearing, which have not hitherto been accounted for in a satisfactory manner. It is principally by means of this muscle that accurate perceptions of sound are communicated to the internal organ, and that the mem- brana tympani is enabled to vary the state of its tension, so as to receive them in the quick succession in which they are conveyed to it. In the human ear, and in that of birds, the radiated fibres of the membrana tympani have their principal at- tachment to the extremity of the handle of the malleus, which is nearly in the centre of the membrane. In the membrane of the elephant, which is oval, the attachment to the handle of the malleus is at some distance from the centre. In the horse, deer, and cat, which have the membrane still more oval than the ele- phant, the handle of the malleus is situated in the long axis of the membrane, with its extremity extending beyond the centre, reaching nearer to the circumference; * Phil. Trans, for 1795.— Orig. VOL. XVIII. 4 D 570 PHILOSOPHICAL TRANSACTIONS. • [ANNO 1800. and the fibres of the radiated muscle are not only attached to its end, but also la- terally to nearly the whole length of its handle. This oval form of the membrana tympani, in those quadrupeds, and the very extensive attachment of the fibres of the radiated muscle to the handle of the mal- leus, may be the reason why their ears are not equally fitted to hear inarticulate sounds, as the ears of birds and of man. Should this radiated muscle of the membrana tympani, which is probably the smallest in the body that has a distinct action, be thought too insignificant to have an office of so much consequence as- signed to it, let it be remembered, that the size of muscles is no indication of their importance, but only of the resistance to be overcome by their action; and that the more delicate actions are performed universally in the body by very small muscles, of which the iris in the eye furnishes a very conspicuous example. Before the mode in which the radiated muscle adapts the membrana tympani to different sounds can be explained, it is necessary that the more important parts of the organ should be enumerated, and the use commonly assigned to each of them pointed out. In man and the more perfect quadrupeds, this organ consists of the following parts: the membrana tympani, situated between the external passage and the cavity of the tympanum; 4 small bones, which form a chain across the tympa- num, connecting the membrana tympani with another membrane lining the fora- men ovale, which opens into the vestibulum, a more internal part of the organ of hearing. The bones are, the malleus, which is united to the membrana tympani by a portion of its handle, and to the 2d bone or incus by its head. The incus, which is connected to the malleus by a capsular ligament, forming a regular joint, the surfaces of the bones being covered with cartilage, but they have only a tremu- lous motion on each other. The incus is also attached to the side of the cavity of the tympanum, where the mastoid cells open, by a ligament on which it moves backward and forward: it is united by its long process to the orbicular bone, which is the smallest in the body, and connects the incus to the 4th bone or stapes, which has its base applied to the foramen ovale, or opening leading into the cavity of the vestibulum. The cavity of the tympanum, in which these bones are situated, com- municates with the external air by means of the Eustachian tube, so that there is always air behind the membrana tympani. The malleus has 3 muscles, by which it is moved; one of them is called the tensor, from its pulling the malleus inwards, and tightening the membrana tympani: the other 2 act in an opposite direction, and relax the membrane; the largest of these is called the obliquus, and is the antagonist of the tensor muscle; the other is very small, and is called the lexator. The stapes has 1 muscle, which acts on it by bringing its basis closer to the foramen ovale. The vestibulum, which is completely separated from the tympanum, by the membrane that lines the foramen ovale, communicates freely with the cochlea and semicircular canals; but these cavities are filled with a watery liquor, and have no communication, as the tympa- VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 571 num has, with the external air. This fact was ascertained in the horse, by the following experiment, repeated several times. The organ of hearing was separated from the skull immediately after death, and the cavity of the tympanum exposed; the parts were then immersed in water, and the stapes removed; by which means, the membrane of the foramen ovale was destroyed, but no globule of air was seen to escape through the water*. The following uses have generally been assigned to the parts now mentioned. The membrana tympani was supposed to be adapted to receive impressions, by the combined action of the tensor and laxator muscles varying the degree of its tension, so as to bring it in unison with different sounds: these impressions were conducted, by the chain of bones, to the vestibulum, cochlea, and semicircular canals; in which cavities, particularly the cochlea, they were supposed to undergo some modi- fication, before they were impressed on the nerves spread on the linings of these cavities. The function of modifying impressions of sound was assigned to the cochlea, partly from the delicacy of its internal structure, supposed to resemble a musical instrument, and partly from there being no other part of the organ ap- parently suited for repeating the variety of delicate sounds which pass into the ear: the changes that could be produced on the membrana tympani by the muscles of the malleus, being considered as incapable of answering that purpose. This slight sketch of the organ of hearing, and of the uses, as they are gene- rally understood, of the different parts, will enable me to point out, with more clear- ness, what parts of the theory appear defective, and what improvements may be made on it. It is true that the membrana tympani is stretched and relaxed by the action of the muscles of the malleus, but not for the purpose alleged in the com- monly received theory. It is stretched, in order to bring the radiated muscle of the membrane itself into a state capable of acting, and of giving those different degrees of tension to the membrane which empower it to correspond with the variety of external tremors: when the membrane is relaxed, the radiated muscle cannot act with any effect, and external tremors make less accurate impressions. The membrana tympani, with its tensor and radiated muscles, may be not unaptly compared to a monochord, of which the membrana tympani is the string; the tensor muscle the screw, giving the necessary tension to make the string perform its proper scale of vibrations; and the radiated muscle acting on the membrane like the moveable bridge of the monochord, adjusting it to the vibrations required to be produced. The combined effects of the action of these muscles give the per- ceptions of grave and acute tones; and, in proportion as their original conformation is more or less perfect, so will their actions be, and consequently the perceptions of sound which they communicate. This mode of subdividing the motions of the membrana tympani between 2 sets of muscles, allotting a portion to each, is not peculiar to this part. A remarkable * This experiment was made by Mr. Clift, who superintends Mr. Hunter's collection, and who has afforded me material assistance in the different parts of this investigation. — Orig. 4D2 bl'l PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. instance of it appears in the rapid movements of the fingers, in performing several actions, and particularly in playing on a musical instrument. In all such rapid motions, the fingers are bent to a certain degree by the long muscles that lie on the fore-arm, to the tendons of which a set of smaller muscles are attached, called lumbricales. These last are unable to produce any effect on the fingers, till elongated in consequence of the action of the long muscles in bending the other joints; the lumbricales then become capable of bending the fingers a little more, and of acting with great rapidity. It is a curious circumstance, that a similar application of muscles should be employed to fit the fingers to produce a quick succession of sounds, and to enable the ear to be impressed by them. From the explanation given of the adjustment of the membrana tympani, the difference between a musical ear and one which is too imperfect to distinguish the different notes in music, will appear to arise entirely from the greater or less nicety with which the muscle of the malleus renders the membrane capable of being truly adjusted. If the tension be perfect, all the variations produced by the action of the radiated muscle will be equally correct, and the ear truly musical; but if the first adjustment is imperfect, though the actions of the radiated muscle may still produce infinite variations, none of them will be correct: the effect, in this respect, will be similar to that produced by playing on a musical instrument which is not in tune. The hearing of articulate sounds requires less nicety in the adjustment, than of inarticulate or musical ones: an ear may therefore be able to perceive the one, though it is not fitted to receive distinct perceptions from the other. The nicety or correctness of a musical ear being the result of muscular action, renders it in part an acquirement; for, though the original formation of these muscles in some ears renders them more capable of arriving at this perfection in their action, early cultivation is still necessary for that purpose; and it is found that an ear, which on the first trials seemed unfit to receive accurate perceptions of sounds, shall, by early and constant application, be rendered tolerably correct, but never can attain excellence. There are organs of hearing in which the parts are so nicely adjusted to each other, as to render them capable of a degree of correct- ness in hearing sounds which appears preternatural. Children who during their in- fancy are much in the society of musical performers, will be naturally induced to attend more to inarticulate sounds than articulate ones, and by these means acquire a correct ear, which, after listening for 2 or 3 years to articulate sounds only, would have been attained with more difficulty. This mode of adapting the ear to different sounds, appears to be one of the most beautiful applications of muscles in the body; the mechanism is so simple, and the variety of effects so great. Several ways in which the correctness of hearing is affected by the wrong actions of the muscles of the tympanum, that appeared to be inexplicable, can be readily accounted for, now that the means by which the membrane adjusts itself are un- derstood. The following are instances of this kind. — Case 1. A gentleman 33 years of age, who possessed a very correct ear, so as to be capable of singing in VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 573 concert, though he had never learned music, was suddenly seized with a giddiness in the head, and a slight degree of numbness in the right side and arm. These feelings went off* in a few hours, but on the 3d day returned, and for several weeks he had returns of the same sensations. It was soon discovered that he had lost his musical ear; he could neither sing a note in tune, nor in the smallest degree per- ceive harmony in the performance of others. For some time he himself thought he had become a little deaf, but his medical attendant was not sensible of that in conversation. On going into the country, he derived great benefit from exercise and sea-bathing. Twenty months after the first attack, he was capable of singing a Scotch air with tolerable exactness, though he could not sing in concert. He continued to improve in his health, and in the course of 2 or 3 years completely recovered his ear for music. In this case, there appeared to be some affection of the brain, which had diminished the actions of the tensor muscles of the mem- branse tympani, through the medium of the nerves which regulate their actions; this gradually went off, and the muscles recovered their former action. Case 2. A young lady was seized with a frenzy, which lasted for several years. Previous to her derangement, she was incapable of singing in tune, from the want of an ear for music; but in the course of her madness she frequently, to the astonishment of her relations, sung a tune with tolerable correctness. This case is the reverse of the former; and, as it arose from a directly contrary affection of the brain, may be considered as the result of an unusual degree of action in the tensor muscles, giving the membrane a more correct adjustment than it had before. Case 3. An eminent music master, after catching cold, found a confusion of sounds in his ears. On strict attention he discovered, that the pitch of 1 ear was 4- a note lower than that of the other; and that the perception of a simple sound did not reach both ears at the same instant, but seemed as 2 distinct sounds, fol- lowing each other in quick succession, the last being the lower and weaker. This complaint distressed him for a long time, but he recovered from it without any medical aid. In this case, the whole defect appears to have been in the action of the radiated muscle, exerted neither with the same quickness nor force in J ear as in the other, so that the sound was half a note too low, as well as later in being impressed on the organ. This affection of the muscle of the membrana tympani is very similar to an affection of the straight muscles of one of the eyes, produ- cing double vision, which I have noticed in a former lecture, when treating of the wrong actions of that organ*, In endeavouring to explain the uses of the more internal parts of the ear, con- siderable advantage may be derived from classing them in 2 divisions; namely, those which are formed for the purpose of receiving impressions conveyed through the medium of liquid or of solid substances; and those adapted to receive im- pressions made by the impulses of an elastic fluid, as the common air. This can be done correctly. Fish, which are formed to hear in water, can have only the * Vide Phil. Trans, for 1797-— Orig. 574 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. parts belonging to the first division ; while all the parts found in the ears of birds and quadrupeds, that are not met with in fish, must belong to the 2d. In fish, the organ consists of a vestibulum and 3 semicircular canals, and these are met with in all fish. In some genera there is an external opening, and substances of a hard nature are found lying loose in the vestibulum: these however cannot be con- sidered as essential parts of the organ, from their not being common to fish in general. Birds have the vestibulum and semicircular canals in common with fish, but they have also a membrana tympani; a slender bone connecting that membrane with the vestibulum ; and an Eustachian tube. In birds, the membrana tympani is convex externally, being pushed forwards by the end of the slender bone above- mentioned. In quadrupeds and man, besides the vestibulum and canals met with in fish, the membrana tympani, the bone connecting it with the vestibulum, and the Eustachian tube, found in birds, there is a cochlea. The membrana tympani is either flat or concave externally ; the bony connection between it and the ves- tibulum is made up of several bones, supplied with muscles to move them in different directions. The parts which compose the organ of hearing in fish, must be intended for re- ceiving impressions conveyed through water: those additional parts met with in birds, and the still greater additions which are found in the quadruped and man, must be intended by nature for rendering more perfect the impressions conveyed to the ear through the medium of the external air. Fish, from the structure of the organ, can only hear sounds ^vhich agitate the water immediately in contact with the head of the fish; so that the impulse is conveyed, without interruption, from the liquid in which they live, to the organ of hearing. Man is capable of hearing in a similar manner to fishes, when a communication of solid parts is kept up between the sounding body and the bones of the skull: experiments of this kind must have been made by many members of the r. s. One of the most common is, applying a watch to the forehead, and stopping the ears, which does not prevent the ticking from being heard: the sound is still more distinct when the watch is applied to the mastoid process. Here, as the sound can neither pass through the meatus externus, nor by the Eustachian tube, while the mouth is kept shut, it evidently must be conducted through the bones of the skull. When the sound produced by boiling water is brought to the ear, by one end of an iron rod resting on the side of the kettle and the other kept in contact with the teeth, the sound is conducted in the same way, though in this case it has by some been supposed to pass through the Eustachian tube. In this mode of hearing, the ves- tibulum and semicircular canals are probably the only parts of the organ which are necessary to convey the impression to the expansion of the auditory nerve. In hearing in air, the use of the membrana tympani in man and quadrupeds has already been explained. Its office in birds is precisely the same; but as in birds this membrane has no tensor muscle to vary its adjustment, but is always kept tense by the pressure of the end of the slender bone, the scale in birds cannot descend so VOL XC.] PHILOSOPHICAL TRANSACTIONS. 575 low as in the human ear; and the intervals in their scale will be more minute, in consequence of the slightest tremor communicated by the action of the radiated muscle to one end of the slender bone being immediately conducted to the internal organ; while in the human ear it has to pass from one bone to another, before it arrives at the vestibulum. The cochlea has been considered by all physiologists as one of the most intricate and curious parts of the ear, and on that account had a most important office assigned to it. This however is now to be transferred to the membrana tympani; and, on attentive consideration of the subject, it will appear impossible for the cochlea to be of any use in modulating sounds, since the ear is only intended to convey impressions received from external bodies; hence, no im- pression can be communicated to the cochlea, which has not been transmitted by the membrana tympani. But if all the varieties of sound are repeated by the membrana tympani, no modulation in the cochlea is required; and when it is con- sidered that the cochlea contains water, instead of air, the effect on every part will be found to be simultaneous. That the cochlea is neither absolutely necessary to fit the organ to be impressed by sounds communicated through air, nor to render it what is termed a musical ear, is sufficiently proved by that part being wanting it) birds, whose organ is particularly adapted to inarticulate sounds. Some birds, particularly bulflnches, can be taught to sing various airs, though it will be always in high notes. If it should be found that birds hear less accurately than quadrupeds, it will favour the idea that the great delicacy of structure of the cochlea, is intended to render the nerves which are spread on it more readily impressed by weak tremors, than those in either the vestibulum or semicircular canals. The cochlea and semi circular canals must be considered as 2 of the most important parts of the ear; their peculiar forms are no doubt adapted to some essential purposes; but what are the precise advantages derived from their particular shape, is at present unknown. There is however much ground to believe, that a more extensive knowledge in comparative anatomy, joined with future observations, may clear up this very curious and obscure part of the physiology of the organ of hearing. In the ele- phant, the small bones, the cochlea and semicircular canals, are larger than those in the human ear, nearly in the same proportion with the increased size of the membrana tympani. In that animal, there is a very remarkable peculiarity; which is, a cellular structure occupying the upper and posterior part of the skull, inclosed between the 2 tables communicating by a considerable aperture with the cavity of the tympanum, and lined by a similar membrane: the cells communicate freely with each other at their lower extremities, but not near the upper, forming irre- gular cylinders, placed in a converging direction, towards the cavity of the tym- panum. There is no middle bony septum, separating the cells of the skull belonging to one ear from those which open into the other, but a ready communi- cation between them. On the anterior part of the skull there is also a similar cellular structure, only much smaller, which communicates with the nose, but is 576 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. entirely separate and distinct from that which forms an appendage to the organ of hearing. That the elephant hears better than other animals, is generally asserted by those who have had opportunities of making observations on the subject. As this opinion has been advanced by men who had no knowledge in anatomy, and had no previous theory to bias their judgment, it is deserving of credit. • The organ of hearing being now found more perfect, and formed on a larger scale than in any other animal with which we are acquainted, considerable weight is given to this opinion. Mr. Corse, who resided many years at Tiperah, in Bengal, and paid particular attention to the manners and habits of elephants, concurs in the belief of their hearing being more acute than that of man. The following cir- cumstances are mentioned by him in proof of it. A tame elephant, who was never reconciled to have a horse moving behind him, though he expressed no un- easiness if the horse was within his view, either before or on one side, could distinguish the sound of a horse's foot at a distance, some time before any person in company heard it: this was known by his pricking up his ears, quickening his pace, and turning his head from side to side. A tame female elephant, which had a young one, was occasionally sent out with other elephants for food, without the young one being allowed to follow. She was not in the habit of pining after her young one, unless she heard its voice; but frequently, on the road home, when no one could distinguish any sound whatever, she pricked up her ears, and made a noise expressive of having heard the call of her young. This having oc- curred frequently, attracted Mr. Corse's notice, and made him, at the time the female elephant used these expressions, stop the party, and desire the gentlemen to listen ; but they were unable to hear any thing till they had approached nearer to the place where the young one was kept. The foregoing observations, the object of which has been to prove that the membrana tympani of the ear has a muscular structure, have already exceeded the limits of a lecture, which prevents us from going further at present into the con sideration of this very curious and important organ. The general analogy between the uses of its different parts and those of the organ of vision, and the similar variations of their actions when under the influence of disease, furnish materials which, on some future occasion, may be laid before the r. s. II. On the Method of determining, from the Real Probabilities of Life, the Values of Contingent Reversions in which Three Lives are involved in the Survivorship. By Wm. Morgan, Esq., F. R. S. p. 22. The several papers, says Mr. M. which I have had the honour of communicating to the r. s., on the doctrine of contingent reversions, contain the greater number of those cases in which 3 lives are concerned in the survivorship. With the view of completing this subject, I have been induced to investigate the remaining pro- VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 577 blems; and, having succeeded in the solution of them, I hope the following will not be considered as an improper addition to my former communications. Problem 1. To determine the value of a given sum, payable on the death of a or b, should either of them be the J st or 2d that fails, of the 3 lives, a, b, and c. — Solution. In this case, the payment of the given sum must certainly take place on the extinction of the joint lives of a and b, independent of c, and therefore the value of the reversion will be = ' ^ "*" — — .* r Prob. 2. To determine the value of a given sum, payable on the decease of a or b, should either of them be the 2d or 3d that shall fail, of the 3 lives, a, b, and c. — From the analytical solution of this problem, which is of considerable extent, it is at length deduced, that the value required will be generally denoted by • , r— 1 ,, A + B + C, . AC x. s into— X (v + ABC - ) + - - ab — - x (ak + bk- 2abk) + s x (af - apc) + _ x (i + ap + d. —r- ). But, it is observed that, unless a and b are very nearly of the same age, and both older than c, this rule will not be sufficiently accurate. If b be the oldest of the 3 lives, the annuities a, ac, and ak, should be continued only for as many years, x} as are equal to the difference between the age of b and that of the oldest life in the table of observations. Let those annuities be respectively denoted by a', ac', and a'k'; also let p denote the probability that c survives b, q the number of persons living opposite to the age of a at the end of x years, then will the value of s, after x years, be = -~ X - , and the whole value of the reversion •11 i • i r~~ 1 v* / ■ A' + B + BC\ Kj, a'c' k , , will be = s into —^ X (v + abc 2i_ ) X -|- — ab — — x (a V-f BK _ 2bk) + A X (A; _ AFC) + £ x (1 + AP + 1. azftj. % x <^£-, a* denoting the value of an annuity on a life x years older than a. If c be the oldest of the 3 lives, let a — s, s — t, t — u, &c. be substituted for their equals a, a", a"', &c, and c — c',c— (c + c"), c — (c -f c" -f- c"), &c. for their equals e,f, g, &c. then will the value of the reversion be found = s into ^ X (V-*(A + B) + ABC) + ^1 - AB + id»=™> + i^«3 If the lives be all equal, the value, according to the first rule, will be = s into r — 1 / \ cc . * , \ . d — X (v - c - -lcc + ccc) + - - cc + - x (kcc - kc) + — x (1 + ct) -| X (tt — ctt); and, according to the 2d rule, it will be = s into ^~ x / i \ i cc i *.(ck — cck) d v^ i' . . dd X (v - c + ccc) + - - cc + — i— -' - - X (1 + ct) + — x (1 + ctt). If these expressions be resolved into their respective series, the value in * The same symbols are uniformly retained in this, as in my last 2 papers on the subject. See Phil, Trans., vol. 81, p. 247.— Orig. VOL. XVIII. 4 E 578 PHILOSOPHICAL TRANSACTIONS. [ANNO 1 80O. t— 1 each case will be found = s . X (v — c — cc + ccc), which is known to be the true value, from self-evident principles. But the solution of this problem may be obtained by the assistance of the 1st problem in my last paper, for the year 1794, supposing, instead of a given sum, it were required to know the value of the reversion of a given estate. For since the possession of this estate is an event which must certainly take place, and the only point to be determined is the time in which it will probably happen, it is ob- vious that no event can postpone the possession, but the contingency of c's being the 2d that fails, of the 3 lives. If therefore the sum of the values of an annuity on the life of b after a, provided a should die before c, and of an annuity on the life of a after b, provided b should die before c, both found by the problem just mentioned, be subtracted from the whole value of the reversion after the joint lives of a and b, the remainder will be the value required. Let x and y respectively denote the annuities found by problem 1st, Phil. Trans, vol. 84, then will the general rule expressing the value of an estate be = v — ab — (x + y), and con- sequently of a given sum = s — X (v — ab — (x + y)), which, when the s (r — l) lives are equal, may be reduced, as in the former cases, to — — x (v — c -— cc -f- ccc). Prob. 3. To determine the value of an estate, or of a given sum, after the decease of a or b, should either of them be the first or last that shall fail, of the 3 lives, a, b, and c. Solution. The reversion of the estate in this problem, like that in the preceding one, cannot be prevented ultimately from taking place; and there is only the single contingency of c's being the first that fails, of the 3 lives, which can postpone the possession of it after the extinction of the joint lives. The whole value therefore of the reversion, after the joint lives of a and b, must in this case be lessened by the sum of the values of an annuity on a's life after b, provided b should survive c; and of an annuity on b's life after a, provided a should survive c, both found by the 2d problem in my last paper, of the year 17Q4. Let these two values be res- pectively denoted by w and z, then will the general rule expressing the value of an estate be = v — ab — (w -|- z), and the value of a given sum = s' (r~ — x (v — AB — (w -f- z)). When the lives are all equal, the value of the reversion, by sub- stituting the values of w and z, becomes = v -f- cc — c — ccc, or s,^r~ X (v _|_ cc — c — ccc), according as it consists of an estate, or a given sum. Prob. 4. To determine the value of a given sum, payable on the death of a, should his life be the 1st or 2d that fails, and should b's life, if it fail, become extinct before the life of c. Solution. In this case, the payment of the given sum can only be prevented by the contingency of c's dying before a, and therefore its value is immediately found VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 5/0 by the solution of the 2d problem in my first paper on this subject, in the year 1788, being no more than " the value of a given sum on the death of a, should c survive him." Prob. 5. To determine the value of a given sum, payable on the death of a, should his life be the 2d or 3d that fails, and should b's life, when it fails, become extinct before the life of c. — The analytical investigation gives for the general value , i .• flV ii • ■ (r— l).(v — a) (r — 1). (bc — abc) k in the solution of this problem, s into a ^ * t-^£ 1 __ x /3.(fk — afk)n . m.(pc- apc) d , »j.(pt — apt). (BK - ABK + Urrm >+ "3^ Wr X (BT ~ ABT ~ -*— I 9 & ,FC AFC , N , B — C + AC — AB , *.(K-Ak) + Tt x (—3 f + ap) + -r + -i-j . Prob. 6. To determine the value of a given sum, payable on the death of a, should his life be the first or last that shall fail, of the 3 lives; and should b's life, if it fail, become extinct before the life of c. — In like manner, the solution of this problem gives, for the value required, the general expression, s into r— 1 , \ . ac ab , md i ' V.v'"'. x d , __ X (v - A - ABC) + --- + -_ X (l + APT) - - X (1 + AT + BT — ABT) — ~ X AFK + ~b X (AF + PC — APC). Prob. 7. To determine the value of a given sum, payable on the death of a, b, and c, provided c shall die after one life in particular, a. — The expression for the solution in this case, is s into^- X (bc — b — abc + y — £7 + ^. X 0 + ap — rf-(1 + APT))— ^ X (bk- abk) -f r; r denoting the value of s, by the 3d problem in the first paper, on the contingency of c's dying after a, anno 1788. This general rule gives the true value of the reversion, when b is the oldest of the 3 lives. But, when c is the oldest of the 3 lives, the general rule will be = s into r — 1 / / \ 1 BC a'b' . m , , , . d . (I 4- apt) *. ___ x (BC - B - ABC) + - - —+ - X (1 + AV - jffiffi? - I X (bk — abk) + r -j- -p' r br3C+lV — — ; — oc denoting the difference between the ages of c and of the oldest person in the table ; p the number of persons living at the age of b after oc years; Br, a'b', and aV, the values of annuities on those single and joint lives for x years; and p the probability that c dies after a, in the paper anno 1794. The foregoing problems, together with those which have been investigated in my former papers, adds Mr. M., comprehend, as far as I can perceive, all the different cases of survivorship between 3 lives. The great number of contingencies on which these reversions depend, must necessarily render the solutions intricate, and conse- quently the general rules complicated and laborious. It would not however be a difficult task to abridge these rules very considerably, without destroying their accu- racy in any great degree ; but this would be foreign to my purpose in these papers, which has uniformly been confined to the investigation of the correct values of the different reversions. Nor do I think that such an abridgment is necessary, as the operations of even the longest of the present rules, may be completed in very 4 e 2 560 PHILOSOPHICAL TRANSACTIONS. [anno 1800. nearly as short a time as the inaccurate approximations which have hitherto been employed for the same purpose. It may not be improper to observe, that the so- lutions in these papers are not only the first which have ever been deduced, in the case of 1 and 3 lives, from just principles and the real probabilities of life ; but that, as to many of the problems, not even an attempt has ever been made to ap- proximate to the value of the reversion. Being now possessed of correct solutions of all the cases in which 2 and 3 lives are involved in the survivorship, we are possessed of all that is really useful, and therefore I feel the greater satisfaction in closing my inquiries on this subject. For, in regard to contingencies depending on 4 or more lives, the cases are not only much too numerous and intricate to admit of a solution, but they occur so seldom in practice, as to render the entire investi- gation of them, were it even possible, a matter of little or no importance. 111. Abstract of a Register of the Barometer, Thermometer, and Rain, at Lyndon, in Rutland, for 1798. By Thos. Barker, Esq. p. 46. Barometer. Thermometer. || Rain. Jan. Feb. Mar Apr. May June July Aug. Sept. Oct. Nov Dec Mom. Aftern Morn. Aftern Morn. Aftern. Morn. Aftern. Morn. Aftern. Morn. Aftern. Morn. Aftern. Morn. Aftern. Morn. Aftern. Morn. Aftern, Morn. Aftern. Morn. Aftern. Highest, Mean of all. Inches. 30.01 30.19 29-84 29.88 30.00 29-98 2973 29.90 29.77 29.87 29.75 30.18 Lowest. Inches. 28.47 28.70 28.71 2S.66 28.75 29.11 28.91 29.25 28.48 28.70 28.21 28.80 Mean. Inches. 29.44 58 44 48 56 61 33 62 32 39 09 43 29.44 In the House. Hig. Low Mean 461 47 £ 49$ 50 51$ 53 58 61 6i$ 64 68 70 66 69 66 70 66 68$ 57\ 60 52 53 42 43 33 34 35$ 37 40 41* 39 41 51 51$ 56 57h 57 59$ 60 6lj 52 51. 44 44 35$ 36 21*. 23$ 40$ 41 41$ 43 43 44 51 51$ 55 56J 62" 64 6l 63 63 65 58$ 60$ 52 53 42$ 43$ 36 36$ 51 Abroad. Hig. Low Mean 49 49 50 54 48$ 58 52$ 68 62$ 71 69 84 67 79 64$ 80 62$ 76 55 63 53 57 42$ 45 28 30 23$ 32$ 28 Z6\ 29 44$ 44 52$ 51 60 54 60$ 51 62$ 44 48 I 32 43$ V as 15$ 13 36$ 40$ 34$ 43 38 44$ 46 57 52 61$ 59h 72 59 70 58$ 70 53 63$ 47 55 38 43 31$ 35 52 Inch. 1.028 1.542 0.532 1.321 1.892 0.950 2.942 1942 2.814 3.030 2.546 1.396 20.938 IV. On the Power of Penetrating into Space by Telescopes; with a Comparative Determination of the Extent of that Power in Natural Vision, and in Telescopes of various Sizes and Constructions ; illustrated by Select Observations. By Wm. Herschel, LL. D., F. R. S. p. 4Q. It will not be difficult to show that the power of penetrating into space by teles- VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 581 copes is very different from the magnifying power, and that, in the construction of instruments, these 2 powers ought to be considered separately. In order to conduct our present inquiry properly, it will be necessary to examine the nature of luminous bodies, aud to enter into the method of vision at a distance. Therefore, to prevent the inaccuracy that would unavoidably arise from the use of terms in their common acceptation, I shall have recourse to algebraic symbols, and to such definitions as may be necessary to fix a precise meaning to some expressions which are often used in conversation, without much regard to accuracy. By luminous bodies I mean, in the following pages, to denote such as throw out light, whatever may be the cause of it: even those that are opaque when they are in a situation to reflect .light, should be understood to be included; as objects of vision they must throw out light, and become intitled to be called luminous. However, those that shine by their own light may be called self-luminous, when there is an occasion to dis- tinguish them. The question will arise, whether luminous bodies scatter light in all directions equally; but, till we are more intimately acquainted with the powers which emit and reflect light, we shall probably remain ignorant on this head. I should remark, that what I mean to say, relates only to the physical points into which we may conceive the surfaces of luminous bodies to be divided ; for, when we take any given luminous body in its whole construction, such as the sun or the moon, the question will assume another form, as will appear hereafter. That light, flame, and luminous gases are penetrable by the rays of light, we know from experience*; it follows therefore, that every part of the sun's disc cannot appear equally luminous to an observer in a given situation, on account of the unequal depth of its luminous atmosphere in different places -j-. This regards only bodies that are self-luminous. But the greatest inequalities in the brightness of luminous bodies in general, will undoubtedly be owing to their natural texture; which may be extremely various, with regard to their power of throwing out light more or less copiously. Brightness I ascribe to bodies that throw out light; and those that throw out most are the brightest. It will now be necessary to establish certain expressions for brightness in different circumstances. In the first place, let us suppose a luminous surface throwing out light, and let the whole quantity of light thrown out by it be called l. Now, since every part of this surface throws out light, let us suppose it divided into a number of luminous physical * In order to put this to a proof, I placed 4 candles behind a screen, at % of an inch distance from each other, so that their flames might range exactly in a line. The first of the candles was placed at the same distance from the screen, and just opposite a narrow slit, \ of an inch long, and \ broad. On the other side of the screen I fixed up a book, at such a distance from the slit that, when the first of the candles was lighted, the letters might not be sufficiently illuminated to become legible. Then, lighting successively the 2d, 3d, and 4th candles, I found the letters gradually more illuminated, so that at last I could read them with great facility ; and by the arrangement of the screen and candles, the light of the 2d, 3d, and 4th, could not reach the book, without penetrating the flames of those that were phced before them. f See the paper on the Nature and Construction of the Sun, Phil, Trans, for l?yo, page 4b\— Orig, 582 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. points, denoted by n. If the copiousness of the emission of light from every phy- sical point of the luminous surface were equal, it might in general be denoted by c; but, as that is most probably never the case, I make c stand for the mean copious- ness of light thrown out from all the physical points of a luminous object. This may be found in the following manner. Let c express the copiousness of emitting light, of any number of physical points that agree in this respect; and let the number of these points be n. Let the copiousness of emission of another number of points be c, and their number n'. And if, in the same manner, other degrees of copiousness be called c1, c3, &c. and their numbers be denoted by n2, n3, &c. then will the sum of every set of points, multiplied by their respective copious- ness of emitting light, give us the quantity of light thrown out by the whole luminous body. That is, l = cn -f- cV + cV, &c; and the mean copiousness of emitting light, of each physical point, will be expressed by cn + cn + c n > &c» = c. It is evident that the mean power, or copiousness of throwing out light, of every physical point in the luminous surface, multiplied by the number of points, must give us the whole power of throwing out light, of the luminous body. That is CN = L. I ought now to answer an objection that may be made to this theory. Light, as has been stated, is transparent ; and, since the light of a point behind the surface of a flame will pass through the surface, ought we not to take in its depth, as well as its superficial dimensions? In answer to this, I recur to what has been said with regard to the different powers of throwing out light, of the points of a luminous surface. For, as light must be finally emitted through the surface, it is but re- ferring all light arising from the emission of points behind the surface, to the surface itself, and the account of emitted light will be equally true. And this will also explain why it has been stated as probable, that different parts of the same luminous surface may throw out different quantities of light. Since therefore the quantity of light thrown out by any luminous body is truly represented by cn, and that an object is bright in consequence of light thrown out, we may say that bright- ness is truly defined by cn. If however there should at any time be occasion for distinction, the brightness arising from the great value of c, may be called the in- trinsic brightness; and that arising from the great value of n, the aggregate bright- ness; but the absolute brightness, in all cases, will still be defined by cn. Hitherto we have only considered luminous objects, and their condition with regard to throwing out light. We proceed now to find an expression for their ap- pearance at any assigned distance; and here it will be proper to leave out of the account, every part of cn which is not applied for the purpose of vision, l re- presenting the whole quantity of light thrown out by cn, we shall denote that part of it which is used in vision, either by the eye or by the telescope, by /. This will render the conclusions that may be drawn hereafter more unexceptionable; for, the quantity of light / being scattered over a small space in proportion to l, it may reasonably be considered as more uniform in its texture; and no scruples about its VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 583 inequality will take place. The equation of light, in this present sense therefore, is cn = /. Now, since we know that the density of light decreases in the ratio of the squares of the distances of the luminous objects, the expression for its quan- tity at the distance of the observer d, will be — . In natural vision, the quantity / undergoes a considerable change, by the opening and contracting of the pupil of the eye. If we call the aperture of the iris a, we find that in different persons it differs considerably. Its changes are not easily to be ascertained; but we shall not be much out in stating its variations to be chiefly between J and 2 tenths of an inch. Perhaps this may be supposed under-rated; for the powers of vision, in a room completely darkened, will exert themselves in a very extraordinary manner. In some experiments on light, made at Bath, in the year 1780, I have often remarked, that after staying some time in a room fitted up for these experiments, where on entering I could not perceive any one object, I was no longer at a loss, in half an hour's time, to find every thing I wanted. It is however probable that the opening of the iris is not the only cause of seeing better after remaining long in the dark ; but that the tranquillity of the retina, which is not disturbed by foreign objects of vision, may render it fit to receive im- pressions such as otherwise would have been too faint to be perceived. This seems to be supported by telescopic vision ; for it has often happened to me, in a fine winter's evening, when, at midnight, and in the absence of the moon, I have taken sweeps of the heavens, of 4, 5, or 6 hours duration, that the sensibility of the eye, in consequence of the exclusion of light from surrounding objects, by means of a black hood which I wear on these occasions, has been very great; and it is evident, that the opening of the iris would have been of no service in these cases, on account of the diameter of the optic pencil, which in the 20 feet teles- cope, at the time of sweeping, was no more than .12 inch. The effect of this in- creased sensibility was such, that if a star of the 3d magnitude came towards the field of view, I found it necessary to withdraw the eye before its entrance, in order not to injure the delicacy of vision acquired by long continuance in the dark. The transit of large stars, unless where none of the 6th or 7th magnitude could be had, have generally been declined in my sweeps, even with the 20 feet telescope. And I remember, that after a considerable sweep with the 40 feet instrument, the appear- ance of Sirius announced itself, at a great distance, like the dawn of the morning, and came on by degrees, increasing in brightness, till this brilliant star at last en- tered the field of view of the telescope, with all the splendour of the rising sun, and forced me to take the eye from that beautiful sight. Such striking effects are a sufficient proof of the great sensibility of the eye, acquired by keeping it from the light. On taking notice, in the beginning of sweeps, of the time that passed, I found that the eye, coming from the light, required near 20m, before it could be sufficiently reposed to admit a view of very delicate objects in the telescope; and that the observation of a transit of a star of the 2d or 3d magnitude would disorder the eve again, so as to require nearly the same time for the re-establishment of its tranquillity. £84 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. The difficulty of ascertaining the greatest opening of the eye, arises from the impossibility of measuring it at the time of its extreme dilatation, which can only happen when every thing is completely dark; but, if the variation of a is not easily to be ascertained, we have, on the other hand, no difficulty to determine the quantity of light admitted through a telescope, which must depend on the diameter of the object-glass, or mirror; for its aperture a may at all times be had a2l by measurement. It follows therefore, that the expression — will always be accu- rate for the quantity of light admitted be the eye; and that — will be sufficiently so for the telescope. For it must be remembered, that the aperture of the eye is also concerned in viewing with telescopes; and that consequently, whenever the pencil of light transmitted to the eye by optical instruments exceeds the aperture of the pupil, much light must be lost. In that case, the expression a2/ will fail ; and therefore in general, if m by the magnifying power, - ought not to exceed a. As I have defined the brightness of an object to the eye of an observer at a a1 1 distance, to be expressed by — , it will be necessary to answer some objections that may be made to this theory. Optical writers have proved, that an object is equally bright at all distances. It may therefore be maintained against me, that since a wall illuminated by the sun will appear equally bright, at whatever distance the ob- server be placed that views it, the sun also, at the distance of Saturn, or still farther from us, must be as bright as it is in its present situation. Nay it may be urged, that in a telescope, the different distance of stars can be of no account with regard to their brightness, and that we must consequently be able to see stars which are many thousands of times farther than Sirius from us; in short, that a star must be infinitely distant not to be seen any longer. Now, objections such as these, ' which seem to be the immediate consequence of what has been demonstrated by mathematicians, and which yet apparently contradict what I assert in this paper, deserve to be thoroughly answered. It may be remembered, that I have dis- tinguished brightness into 3 different kinds. Two of these, which have been dis- criminated by intrinsic and absolute brightness, are, in common language, left without distinction. In order to show that they are so, I might bring a variety of examples from common conversation; but taking this for granted, it may be shown that all the objections I have brought against my theory have their foundation in this ambiguity. The demonstrations of opticians, with regard to what I call in- trinsic brightness, will not oppose what I affirm of absolute brightness; and I shall have nothing further to do than to show that what mathematicians have said, must be understood to refer entirely to the intrinsic brightness, or illumination of the picture of objects on the retina of the eye: from which it will clearly follow, that their doctrine and mine are perfectly reconcileable; and that they can be at variance only when the ambiguity of the word brightness is overlooked, and objections, such as I have made, are raised where the word brightness is used as absolute, when we should have kept it to the only meaning it can bear in the mathematicians' theorem. ▼OL. XC.J PHILOSOPHICAL TRANSACTIONS. 585 The first objection I have mentioned is, that the sun, to an observer on Saturn, must be as bright as it is here on earth. Now by this cannot be meant, that an inhabitant standing on the planet Saturn, and looking at the sun, should absolutely receive as much light from it as one on earth receives when he sees it; for this would be contrary to the well-known decrease of light at various distances. The objection therefore can only go to assert, that the picture of the sun, on the retina of the Saturnian observer, is as intensely illuminated as that on the retina of the terrestrial astronomer. To this I perfectly agree. But let those who would go far- ther, and say that therefore the sun is absolutely as bright to the one as to the other, remember that the sun on Saturn appears to be 100 times less than on the earth; and that consequently, though it may there be intrinsically as bright, it must here be absolutely 100 times brighter. The next objection relates to the fixed stars. What has been shown in the pre- ceding paragraph, with regard to the sun, is so entirely applicable to the stars, that it will be very easy to place this point also in its proper light. As I have assented to the demonstration of opticians with regard to the brightness of the sun, when seen at the distance of Saturn, provided the meaning of this word be kept to the intrinsic illumination of the picture on the retina of an observer, I can have no hesitation to allow that the same will hold good with a star placed at any assignable distance. But I must repeat, that the light we can receive from stars is truly ex- pressed by —^ and that therefore their absolute brightness must vary in the in- verse ratio of the squares of their distances. Hence I am authorised to conclude, and observation abundantly confirms it, that stars cannot be seen by the naked eye, when they are more than 7 or 8 times farther from us than Sirius; and that they become, comparatively speaking, very soon invisible with our best instruments. It will be shown hereafter, that the visibility of stars depends on the penetrating power of telescopes, which I must repeat falls indeed very short of showing stars that are many thousands of times farther from us than Sirius ; much less can we ever hope to see stars that are all but infinitely distant. If now it be admitted that the expressions we have laid down are such as agree with well-known facts, we may proceed to vision at a distance; and first with respect to the naked eye. Here the power of penetrating into space, is not only confined by nature, but is also occasionally limited by the failure in brightness of luminous objects. Let us see whether astronomical observations, assisted by mathematical reasoning, can give us some idea of the general extent of natural vision. Among the reflecting luminous objects, our penetrating powers are sufficiently ascertained. From the moon we may step to Venus, to Mercury, to Mars, to Jupiter, to Saturn, and last of all to the Georgian planet. An object seen by reflected light at a greater distance than this, it has never been allowed us to perceive; and it is indeed much to be admired, that we should see borrowed illumination to the amazing distance of more than 18 hundred millions of miles; especially when that light, in vol. xviii. 4 F 586 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. coming from the sun to the planet, has to pass through an equal space, before it can be reflected, by which it must be so enfeebled as to be above 368 times less intense on that planet than it is with us, and when probably not more than one- third part of that light can be thrown back from its disc* The range of natural vision with self-luminous objects, is incomparably more extended, but less accurately to be ascertained. From our brightest luminary, the sun, we pass immediately to very distant objects; for, Sirius, Arcturus, and the rest of the stars of the first magnitude, are probably those that come next; and what their distance may be, it is well known, can only be calculated imperfectly from the doctrine of parallaxes, which places the nearest of them at least 412530 times farther from us than the sun. In order to take a 2d step forwards, we must enter into some preliminary considerations, which cannot but be attended with con- siderable uncertainty. The general supposition, that stars, at least those which seem to be promiscuously scattered, are probably one with another of a certain magnitude, being admitted, it has already been shown in a former paper,'}- that after a certain number of stars of the first magnitude have been arranged about the sun, a farther distant set will come in for the 2d place. The situation of these may be taken to be, one with another, at about double the distance of the former from us. By directing our view to them, and thus penetrating one step farther into space, these stars of the 2d magnitude furnish us with an experiment that shows what phenomena will take place, when we receive the illumination of 2 very remote ob- jects, equally bright in themselves, of which one is at double the distance of the other. The expression for the brightness of such objects, at all distances, and with any aperture of the iris, according to our foregoing notation, will be — ; and a method of reducing this to an experimental investigation will be as follows. Let us admit that a Cygni, p Tauri, and others, are stars of the 2d magnitude, such as are here to be considered. We know, that in looking at them and the former, the aperture of the iris will probably undergo no change; since the difference in brightness, between Sirius, Arcturus, a Cygni, and (3 Tauri, does not seem to affect the eye so as to require any alteration in the dimensions of the iris; a there- fore becomes a given quantity, and may be left out. Admitting also, that the latter of these stars are probably at double the distance of the former, we have d2 in one case 4 times that of the other; and the 2 expressions for the brightness of the stars, will be / for those of the 1st magnitude, and ±1 for those of the 2d. The quantities being thus prepared, what I mean to suggest by an experiment is, that since sensations, by their nature, will not admit of being halved or quartered, we come thus to know by inspection what phenomenon will be produced by the 4th part of the light of a star of the 1st magnitude. In this sense, I think we must * According to Mr. Bouguer, the surface of the moon absorbs about \ of the light it receives from be sun. SeeTraitc d'Optique, p. 122. f p*"l. Trans, for the year 1796, P- 1&>, 1^7, 168.— Orig. VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 587 take it for granted, that a certain idea of brightness, attached to the stars which are generally denominated to be of the 2d magnitude, may be added to our expe- rimental knowledge; for, by this means, we are informed what we are to under- stand by the expressions — , . . ,z, -pp — ^.* We cannot wonder at the im- mense difference between the brightness of the sun and that of Sirius; since the first 2 expressions, when properly resolved, give us a ratio of brightness of more than 170 thousand millions to 1; whereas the latter 2, as has been shown, give only a ratio of 4 to 1 . What has been said will carry us, with very little addition, to the end of our unassisted power of vision to penetrate into space. We can have no other guide to lead us a 3d step than the same before-mentioned hypothesis; in consequence of which however it must be acknowledged to be sufficiently probable, that the stars of the 3d magnitude may be placed about 3 times as far from us as those of the 1st. It has been seen, by my remarks on the comparative brightness of the stars, that I place no reliance on the classification of them into magnitudes; but in the present instance, where the question is not to ascertain the precise brightness of any one star, it is quite sufficient to know that the number of the stars of the first 3 different magnitudes, or different brightnesses, answers, in a general way, sufficiently well to a supposed equally distant arrangement of a 1st, 2d, and 3d set of stars about the sun. Our 3d step forwards into space, may there- fore very properly be said to fall on the pole star, on y Cygni, t Bootis, and all those of the same order. As the difference, between these and the stars of the preceding order, is much less striking than that between the stars of the 1st and 2d aH Q.H magnitude, we also find that the expressions — = — ?—, and . . )tJ are not in the high ratio of 4 to 1 , but only as 9 to 4, or 2^ to 1 . Without tracing the brightness of the stars through any farther steps, I shall only remark, that the diminution of the ratios of brightness of the stars of the 4th, 5th, 6th, and 7th magnitudes, seems to answer to their mathematical expressions, as well as, from the first steps we have taken, can possibly be imagined. The cal- culated ratio, for instance, of the brightness of a star of the 6th magnitude, to that of one of the 7th, is but little more than 1 £ to 1 ; but still we find by expe- rience, that the eye can very conveniently perceive it. At the same time, the faint- ness of the stars of the 7th magnitude, which require the finest nights, and the best common eyes to be perceived, gives us little room to believe that we can pene- trate much farther into space, with objects of no greater brightness than stars. But, since it may be justly observed, that in the foregoing estimation of the pro- portional distance of the stars, a considerable uncertainty must remain, we ought to make a proper allowance for it, and, in order to see to what extent this should go, we must make use of the experimental sensations of the ratios of brightness we have now acquired, in going step by step forward; for, numerical ratios of * The names of the objects, ©, Sirius, 0Tauri, are here used to express their distance from us. — Orig. 4 P 2 588 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. brightness, and sensations of them, as has been noticed before, are very difFerent things. And since, from the foregoing considerations, it may be concluded, that as far as the 6th, 7th, or 8th magnitude, there ought to be a visible general dif- ference between stars of one order and that of the next following, I think, from the faintness of the stars of the 7th magnitude, we are authorized to conclude, that no star, 8, 9, or at most 10 times as far from us as Sirius, can possibly be per- ceived by the natural eye. The boundaries of vision, however, are not confined to single stars. Where the light of these falls short, the united lustre of sidereal systems will still be per- ceived. In clear nights, for instance, we may see a whitish patch in the sword- handle of Perseus, which contains small stars of various sizes, as may be ascer- tained by a telescope of a moderate power of penetrating into space. We easily see the united lustre of them, though the light of no one of the single stars could have affected the unassisted eye. Considerably beyond the distance of the former must be the cluster discovered by Mr. Messier, in lj64 ; north following H Gemi- norum. It contains stars much smaller than those of the former cluster; and a telescope should have a considerable penetrating power, to ascertain their brightness properly, such as my common 10-feet reflector. The night should be clear, in order to see it well with the naked eye, and it will then appear in the shape of a small nebula. Still farther from us must be the nebula between » and £ Herculis, discovered by Dr. Halley, in 17 14. The stars of it are so small that it has been called a nebula; and has been regarded as such, till my instruments of high pene- trating powers were applied to it. It requires a very clear night, and the absence of the moon, to see it with the natural eye. Perhaps, among the farthest objects that can make an impression on the eye, when not assisted by telescopes, may be reckoned the nebula in the girdle of Andromeda, discovered by Simon Marius, in 1612. It is however not difficult to perceive it, in a clear night, on account of its great extent. From the powers of penetrating into space by natural vision, we proceed now to that of telescopes. It has been shown, that brightness, or light, is to the naked eye truly represented by -; in a telescope therefore, the light admitted will be expressed by — • Hence it would follow, that the artificial power of penetrating into space should be to the natural one as a to a. But this proportion must be corrected by the practical deficiency in light reflected by mirrors, or transmitted through glasses; and it will in a great measure depend on the circumstances of the workmanship, materials, and construction of the telescope, how much loss of light there will be sustained. In order to come to some determination on this subject, I made many experi- ments with plain mirrors, polished like my large ones, and of the same composi- tion of metal. The method I pursued was that proposed by Mr. Bouguer, in his Traite d'Optique, page 16, fig. 3; but I brought the mirror, during the trial, as VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 58Q close to the line connecting the two objects as possible, in order to render the re- flected rays nearly perpendicular. The result was, that out of 100 thousand inci- dent rays, 67262 were returned; and therefore, if a double reflection takes place, only 45242 will be returned. Before this light can reach the eye, it will suffer some loss in passing through the eye-glass; and the amount of this I ascertained, by taking a highly polished plain glass, of nearly the usual thickness of optical glasses of small focal lengths. Then, by the method of the same author, page 21, fig. 5, I found, that out of 100 thousand incident rays, Q4825 were trans- mitted through the glass. Hence, if 2 lenses be used, 89918; and with 3 lenses, 85265 rays will be transmitted to the eye. Then by compounding we shall have, in a telescope of my construction with one reflection, 63796 rays, out of 100 thousand, come to the eye. In the Newtonian form, with a single eye lens, 42901 ; and with a double eye-glass 40681 will remain for vision. There must always re- main a considerable uncertainty in the quantities here assigned ; as a newly-polished mirror, or one in high preservation, will give more light than another that has not those advantages. The quality of metal also will make some difference; but if it should appear by experiments, that the metals or glasses in use will yield more or less light than here assigned, it is to be understood that the corrections must be made accordingly. We proceed now to find a proper expression for the power of penetrating into space, that we may be enabled to compare its effects, in different telescopes, with that of the natural eye. Since then the brightness of luminous objects is inversely as the squares of the distances, it follows, that the penetrating power must be as the square roots of the light received by the eye. In natural vision therefore, this power is truly expressed by Va2!; and, since we have now also obtained a proper correction x, we must apply it to the incident light with telescopes. In the New- tonian and other constructions, where 2 specula are used, there will also be some loss of light on account of the interposition of the small speculum; therefore, putting b for its diameter, we have a2 — U2 for the real incident light. This being corrected as above, will give the general expression */ {xl X (a* — U1)) for the same power in telescopes. But here we are to take notice, that in refractors, and in telescopes with 1 reflection, b will be = 0, and therefore is to be left out. Then, if we put natural light / = 1 , and divide by a> we have the general form ^' ^A """ il for the penetrating power of all sorts of telescopes, compared to that of the natural eye as a standard, according to any supposed aperture of the iris, and pro- portion of light returned by reflexion, or transmitted by refraction. In the following investigation we shall suppose a = 2 tenths of an inch, as being perhaps nearly the general opening of the iris, in star-light nights, when the eye has been some moderate time in the dark. The value of the corrections for loss of light will, stand as has been given before. We may now proceed to determine the powers of the instruments that have 5Q0 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. been used in my astronomical observations; but, as this subject will be best ex- plained by a report of the observations themselves, I shall select a series of them for that purpose, and relate them in the order which will be most illustrating. First, with regard to the eye, it is certain that its power, like all our other facul- ties, is limited by nature, and is regulated by the permanent brightness of objects, as has been shown already, when its extent with reflected light was compared to its exertion on self-luminous objects. It is further limited on borrowed light, by the occafional state of illumination ; for when that becomes defective at any time, the power of the eye will then be contracted into a narrower compass; an instance of which is the following. In the year 177^, when I had erected a telescope of 20 feet focal length, of the Newtonian construction, one of its effects by trial was, that when towards evening, on account of darkness, the natural eye could not penetrate far into space, the telescope possessed that power sufficiently to show, by the dial of a distant church steeple, what o'clock it was, notwithstanding the naked eye could no longer see the steeple itself. Here I only speak of the penetrating power; for though it might require magnifying power to see the figures on the dial, it could require none to see the steeple. Now the aperture of the telescope being 12 inches, and the construction of the Newtonian form, its penetrating power, when calculated according to the given formula, will be 4V (.429 X (120Q — 152)) = 38. 99, a, b, and a, being all expressed in tenths of an inch.* From the result of this computation it appears, that the circumstance of seeing so well, in the dusk of the evening, may be easily accounted for, by a power of this telescope to penetrate 39 times farther into space than the natural eye could reach, with objects so faintly illuminated. This observation completely refutes an objection to telescopic vision, that may be drawn from what has also been demonstrated by optical writers; namely, that no telescope can show an object brighter than it is to the naked eye. For, in order to reconcile this optical theory with experience, I have only to say, that the objection is entirely founded on the same ambiguity of the word brightness that has before been detected. It is perfectly true, that the intrinsic illumination of the picture on the retina, which is made by a telescope, cannot exceed that of natural vision; but the absolute brightness of the magnified picture by which telescopic vision is performed, must exceed that of the picture in natural vision, in the same ratio in which the area of the magnified picture exceeds that of the natural one; supposing the intrinsic brightness of both pictures to be the same. In our present instance, the steeple and clock-dial were rendered vfsible by this increased absolute brightness of the object, which in natural vision was 15 hun- dred times inferior to what it was in the telescope. And this establishes beyond a doubt, that telescopic vision is performed by the absolute brightness of objects; * 1 have given the figures, in all the following equations of the calculated penetrating powers, in order to show the constructions of my instruments to those who may wish to be acquainted with them.— Orig. VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 5QI for, in the present case, I find by computation, that the intrinsic brightness, so far from being equal in the telescope to that of natural vision, was inferior to it in the ratio of 3 to 7. The distinction between magnifying power, and a power of penetrating into space, could not but be felt long ago, though its theory has not been inquired into. This undoubtedly gave rise to the invention of those very useful short telescopes called night-glasses. When the darkness of the evening curtails the natural pene- trating power, they come in very seasonably, to the relief of mariners that are on the look-out for objects which it is their interest to discover. Night-glasses, such as they are now generally made, will have a power of penetrating 6 or 7 times farther into space than the natural eye. For, by the construction of the double eye-glass, these telescopes will magnify 7 or 8 times; and the object-glass being I viewed Saturn with the 20 and 40-feet telescopes. " 20- feet : The 5th satellite of Saturn is very small. The 1st, 2d, 3d, 4th, 5th, and the new 6th satellite, are in their calculated places." " 40-feet : I see the new 6th satellite much better with this instrument than with the 20-feet. The 5th is also much larger here than in the 20-feet ; in which it was nearly the same size as a small fixed star, but here it is considerably larger than that star." Here the supe- rior penetrating power of the 40-feet telescope showed itself on the 6th satellite of Saturn, which is a very faint object ; as it had also a considerable advantage in magnifying power, the disc of the 5th satellite appeared larger than in the 20-feet. But the small star, which may be said to be beyond the reach of magnifying power, could only profit by the superiority of the other power. Nov. 21, 1791, 40-feet reflector, ; power 370. " The black division on the ring is as dark as the heavens about Saturn, and of the same colour." " The sha- dow of the body of Saturn is visible on the ring, on the following side ; its colour is very different from that of the dark division. The 5th satellite is less than the 3d : it is even less than the 2d." 20-feet reflector ; power 300. " The 3d sa- tellite seems to be smaller than it was the last night but one. The 4th satellite seems to be larger than it was the 19th. This telescope shows the satellites not nearly so well as the 40-feet." Here the magnifying power being nearly alike, the superiority of the 40-feet telescope must be ascribed to its penetrating power. The different nature of the two powers above-mentioned being thus evidently established, I must now remark that, in some respects, they even interfere with each other; a few instances of which I shall give. August 24, 1783, I viewed 4 g2 5q6 philosophical transactions. [anno 1800. the nebula north preceding Flamsteed's 1 trianguli, discovered by Mr. Messier, in 1764. " 7-feet reflector ; power 57. There is a suspicion that the nebula con- sists of exceedingly small stars. With this low power it has a nebulous appear- ance ; and it vanishes when I put on the higher magnifying powers of 278 and 460." — Oct. 28, 1794, I viewed the same nebula with a 7-feet reflector. " It is large, but very faint. With 120 it seems to be composed of stars, and I think I see several of them ; but it will bear no magnifying power." In this experiment, magnifying power was evidently injurious to penetrating power. I do not account for this on the principle that by magnifying we make an object less bright ; for when opticians have also demonstrated that brightness is diminished by magnifying, it must again be understood as relating only to the intrinsic brightness of the mag- nified picture ; its absolute brightness, which is the only one that concerns us at present, must always remain the same *. The real explanation of the fact I take to be, that while the light collected' is employed in magnifying the object, it cannot be exerted in giving penetrating power. June 18, 1799> I viewed the planet Venus with a 10-feet reflector. " Its light is so vivid that it does not require, nor will it bear, a penetrating power of 29, neither with a low nor with a high magnifying power." This is not owing to the least imperfection in the mirror, which is truly parabolical, and shows with all its aperture open, and a magnifying power of f)00, the double star y Leonis in the greatest perfection. " It showed Venus perfectly well defined with a penetrating power as low as 14, and a magnifying power of 400, or 600." Here, penetrating power was injurious to magnifying power ; and that it necessarily must be so, when carried to a high pitch, is evident ; for, by enlarging the aperture of the telescope, we increase the evil that attends magnifying, which is, that we cannot magnify the object without magnifying the medium. Now since the air is very seldom of so homogeneous a disposition as to admit to be magnified highly, it follows that we must meet with impurities and obstructions, in proportion to its quantity. But the contents of the columns of air through which we look at the heavens by telescopes, being of equal lengths, must be as their bases, that is, as the squares of the apertures of the telescopes ; and this is in a much higher ratio than that of the increase of the power of penetrating into space. From my long experience in these matters, I am led to apprehend, that the highest power of mag- * This may be proved thus. The mean intrinsic brightness, or rather illumination, of a point of the picture on the retina, will be all the light that falls on the picture, divided by the number of its points ; or c = — . Now since, with a greater magnifying power m, the number of points n increases as the N squares of the power, the expression for the intrinsic brightness — , will decrease in the same ratio ; and / 1 m1 . it will consequent^ be in general n a m1, and — or c a — 3 that is, by compounding cn a — - = * = 1 5 Km2 "* or absolute brightness a given quantity. M. Bouguer has carefully distinguished intrinsic and absolute brightness, when he speaks of the quantity of light reflected from a wall, at different distances. Traitc d'Optique, page 39 and 40. — Orig. VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 5Q7 nifying may possibly not exceed the reach of a 20 or 25-feet telescope ; or may even lie in a less compass than either. However, in beautiful nights, when the outside of our telescope is dropping with moisture discharged from the atmosphere, there are now and then favourable hours, in which it is hardly possible to put a limit to magnifying power. But such valuable opportunites are extremely rare ; and, with large instruments, it will always be lost labour to observe at other times. As I have hinted at the natural limits of magnifying power, I shall venture also to extend my surmises to those of penetrating power. There seems to be room for a considerable increase in this branch of the telescope ; and, as the penetrating power of my 40- feet reflector already goes to 191.69, there can hardly be any doubt but that it might be carried to 500, and probably not much farther. The natural limit seems to be an equation between the faintest star that can be made visible, by any means, and the united brilliancy of star-light. For, as the light of the heavens, in clear nights, is already very considerable in my large telescope, it must in the end be so increased, by enlarging the penetrating power, as to become a balance to the light of all objects that are so remote as not to exceed in brightness the general light of the heavens. Now if p be put for penetrating power, we have /^- = a = 10 feet 5.2 inches, for an aperture of a reflector, on my construc- tion, that would have such a power of 500. But, to return to our subject ; from what has been said before, we may conclude, that objects are viewed in their greatest perfection when, in penetrating space, the magnifying power is so low as only to be sufficient to show the object well ; and when, in magnifying objects, by way of examining them minutely, the space-pene- trating power is no higher than what will suffice for the purpose ; for, in the use of either power, the injudicious overcharge of the other, will prove hurtful to perfect vision. It is remarkable that, from very different principles, I have formerly determined the length of the visual ray of my 20-feet telescope on the stars of the milky way, so as to agree nearly with the calculations that have been given.* The extent of what I then figuratively called my sounding line, and what now appears to answer to the power of penetrating into space, was shown to be not less than 415, 46 1, and 497 times the distance of Sirius from the sun. We now have calculated that my telescope, in the Newtonian form, at the time when the paper on the Con- struction of the Heavens was written, possessed a power of penetration, which ex- ceeded that of natural vision 6 1.1 8 times; and, as we have also shown, that stars at 8, 9, or at most 10 times the distance of Sirius, must become invisible to the eye, we may safely conclude, that no single star above 489, 551, or at most 612 times as far as Sirius, can any longer be seen in this telescope. Now the greatest length of the former visual ray, 497, agrees nearly with the lowest of these present num- bers, 489 5 and tne higher ones are all in favour of the former computation ; for * Phil. Trans, vol. 75, p. 217, 248.— Orig. 508 PHILOSOPHICAL TRANSACTIONS. [ANNO 1600. that ray, though taken from what was perhaps not far from its greatest extent might possibly have reached to some distance beyond the apparent bounds of the milky way: but if there had been any considerable difference in these determinations we should remember that some of the data by which I have now calculated are only assumed. For instance, if the opening of the iris, when we look at a star of the 7 th magnitude, should be only -^ of an inch and a half, instead of 2, then a, in our formula, will be = 1.5 ; which, when resolved, will give a penetrating power of 81.58 ; and therefore on this supposition, our telescope would easily have shown stars 571 times as far from us as Sirius ; and only those at 653, 734, or 8 16 times the same distance, would have been beyond its reach. My reason for fixing on T*T, rather than a lower quantity, was, that I might not run a risk of over-rating the powers of my instruments. I have it however in contemplation, to determine this quantity experimentally, and perceive already, that the difficulties which attend this subject may be overcome. It now only remains to show, how far the penetrating power, 192, of my large reflector, will really reach into space. Then, since this number has been calculated to be in proportion to the standard of natural vision, it follows, that if we admit a star of the 7th magnitude to be visible to the unassisted eye, this telescope will show stars of the 1342d magnitude. But, as we did not stop at the single stars above-mentioned, when the penetration of the natural eye was to be ascertained, so we must now also call the united lustre of sidereal systems to our aid in stretching forwards into space. Suppose therefore a cluster of 5000 stars to be at one of those immense distances, to which only a 40-feet reflector can reach, and our formula will give us the means of calculating what that may be. For, putting s for the number of stars in the cluster, and d for its distance, we have — ^-i = D;* which, on computation, comes out to be above 1 If millions of millions of millions of miles! A number which exceeds the distance of the nearest fixed star, at least 300000 times. From the above considerations it follows, that the range for observing, with a telescope such as my 40-feet reflector, is indeed very extensive, we have the inside of a sphere to examine, the radius of which is the immense distance just now as- signed to be within the reach of the penetration of our instruments, and of which all the celestial objects visible to the eye, put together, form as it were but the kernel, while all the immensity of its thick shell is reserved for the telescope. It follows, in the next place, that much time must be required for going through so extensive a range. The method of examining the heavens, by sweeping over space, instead of looking merely at places that are known to contain objects, is the only one that can be useful for discoveries. In order therefore to calculate how long a time it must take to sweep the heavens, as far as they are within the reach of my 40-feet telescope, charged with a magnifying power of 1000, I have had recourse to my journals, to find how many favourable hours we may annually hope for in * d = 1 1,765475,948678,678679 miles.— Orig. VOL. XC.] PHILOSOPHICAL TRANSACTIONS. QQQ this climate. It is to be noticed, that the nights must be very clear; the moon absent ; no twilight ; no haziness ; no violent wind ; and no sudden change of temperature ; then also, short intervals for filling up broken sweeps will occasion delays ; and, under all these circumstances, it appears that a year which will afford 90, or at most 100 hours, is to be called very productive. In the equator, with my 20-feet telescope, I have swept over zones of 2°, with a power of 157 ; but an allowance of 10 minutes in polar distance must be made, for lapping the sweeps over each other where they join. As the breadth of the zones may be increased towards the poles, the northern hemisphere may be swept in about 40 zones: to these we must add 19 southern zones ; then, 59 zones, which, on account of the sweeps lapping over each other about 5ra of time in right ascension, we must reckon of 25 hours each, will give 1475 hours. And, allowing 100 hours per year, we find that, with the 20-feet telescope, the heavens may be swept in about 14 years and -§-. Now the time of sweeping, with different magnifying powers, will be as the squares of the powers ; and, putting p and t for the power and time in the 20- feet telescope, and p = 1000 for the power in the 40, we shall have jb2 : t : : p2 : -j = 5Q840. Then, making the same allowance of 100 hours per year, it appears that it will require not less than 598 years, to look with the 40-feet reflector, charged with the above-mentioned power, only one single mo- ment into each part of space ; and even then, so much of the southern hemisphere will remain unexplored, as will take up 213 years more to examine. V. A Second Appendix to the Improved Solution of a Problem in Physical Astro- nomy, inserted in the Philos. Trans, for \7Q&, containing some further Remarks, and Improved Formula for computing the Co-efficients a and b ; by which the Arithmetical Work is considerably Shortened and Facilitated. By the Rev. John Hellins, B. D., F. R. S., &c. p. 86. It was shown, in art. 9, of the first appendix, how the common logarithm of the fraction *• ~ CC , when c is expressed in numbers, may be taken out from the best log. tables. Yet that method of obtaining the value of «, easy as it is, requires, first, a search in the table for the angle of which c is the sine, and generally a pro- portion for the fractional parts of a second ; then, a division of the degrees, minutes, and seconds contained in that angle, by 2 ; and, thirdly, another search for the logarithmic tangent of half the angle, and another proportion to find the fractional parts of a second. Mr. H. was therefore desirous of finding some easier and shorter method of performing the whole business, without the use of any trigonometrical tables, in which time is required, not only in searching for logarithms, but also in making proportions for the fractional parts of a second ; and, after some considera- tion, he discovered that which is here explained. This method then, together with some further observations made for facilitating and abridging the work of computing 600 PHILOSOPHICAL TRANSACTIONS. [ANNO 1 800. the values of the letters a and b. used in the former paper, make up the contents of this paper. The h.l. £-2 , which was denoted by a, both in the solution of the 2 cc 3 c* % *)C^ problem and in the appendix, is = h.l. -, — — — ^-^ — ' &c. and if, for the sake of distinction, the Roman letter a be put for h.l. - , we shall have x = a CC %C^ — — — — , &c. (of which series, the first 3 terms are sufficient for the present purpose) ; and this value of a being written for it in the expression « x 3.5 8.8 1 4- -re. 4- 8.8 ' " v 4 4#8 3 3 5 (1 + - cc -f- — '— c4), which occurs in the first theorem in art. 12, of the first ap- 3 3 5 cc 3 pendix, we have (l -f -cc -f Y~Tc4) X (a — — — TrT0*) '* tnat iS> by actual mul- tiplication, - zee 4- — — - ac 8 1 8.8 1 3 -cc — r 16 Now the terms — ±cc and — -^c4 may very easily be added to the terms fee and gcA, i.e. to 0*1 036802 cc and 0*o687064c4, which will then become — 0'1463J98cc, and — 0*11 87936V; and, by denoting the co-efficients of these new terms by the Roman letters — f and — g respectively, the first theorem in the art. before- mentioned, or the value of a, is ~~ *(a + b)% X J \- e — ice — gc* + a -f -ace + -g^ac4. o 1 'i 3 5 21 The expression a. (- + -rr7.ee + ■ ' ■ c4), which occurs in the value of a', in art. 12, of the first appendix, is = r 3 , 3.5 , 3.5.21 4-4 r 3 . 3.5 . 3.5.21 4 \Z + mcc + EH--S< I S ia + 47Tiacc + iTiTsI*' 1 1 3 . f — S 3 19. 3 19 Here again the terms — -~cc and — — ->c4 may very easily be added to the terms ice and kc*, i. e. to 00551 502 cc and 0*0408309 c4, and we have the two new terms — 01323498cc and — 0.1076091c4. Let the coefficients of these two new terms be denoted by the Roman letters — i and — k respectively, and the 2d theorem in art. 1 2 of the first appendix becomes L' = i x \ : + i- + h - ice - kc4 ■ CC ' 3 , 3.5 . 3.5.21 -a 4 ace 4- ac . 4 ' 4. 12 ~ 4. 12.32 The product of a. (2 4- \cc + -fVc4), which is found in the 3d theorem of the art. before referred to, is = VOL. XC.] PHILOSOPHICAL TBANSACTIONS. 601 5 2+hcc+^c' I = S 2a + ?•" + if**4 Here likewise, the terms — ±cc and — -jVc4 maybe added to 0'3465736cc and 0*1 793226c4, which are = Ice and *nc4 respectively; the co-efficients of which being denoted by the Roman letters 1 and m, the 3d theorem in the art. before re- ferred to becomes — Ice — mc4 *$ 2a 2 B~ ~A **(- + *)* X 1 +aa+ Iacc+ - 2 ' 2 . 16 These new forms, to which the theorems are now brought, it is evident are no less convenient, and on examination they will be found no less accurate, than the original ones ; and that the common logarithm of -, and consequently the hy- perbolic logarithm of it, is much more easily and expeditiously obtained than the 1 4- jk/(\ — cc) common logarithm of , is too obvious to need a description ; and therefore it follows, that a computation by these new formulae will be easier and shorter than by those in the first appendix. Mr. H. besides mentions some other subordinate expedients for facilitating the computations ; he then adds as follows. Having now described these short and easy methods of computing the values of a, b, and c, and of deriving the other logarithmic terras from them, and having in- troduced a new and more compendious notation of several of the terms in each of the first 3 theorems, it will be proper next to exhibit those theorems in this im- proved state, and, after that, to give an example or 2 of computing by them. 1 C "l+e-fcc-gc4 = *(« + 9i X I + a + |acc(=b) + j^{ac4(=c). -| \- h — ice — kc4 3c4 2a 2 _ 1 f 3. B = -r- A — — Ice — mc4 The ingenious author then concludes with an example or two, computed in numbers by these theorems. Vh Account of a Peculiarity in the Distribution of the Arteries sent to the Limbs of Slow-moving Animals ; with some other Similar Facts. By Mr. Anthony Carlisle, Surgeon, p. 98. The lemur tardigradus, in its injected state, accompanies this paper ; and, for VOL. xviii. 4 H 002 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. the kind of preparation, the vessels are filled with more than ordinary success. The arteries alone are injected ; and the peculiarity of their arrangement is to be ob- served in the axillary arteries, and in the iliacs. These vessels, at their entrance into the upper and lower limbs, are suddenly divided into a number of equal-sized cylinders, which occasionally anastomose with each other. They are exclusively distributed on the muscles ; while the arteries sent to all the parts of the body, excepting the limbs, divide in the usual arborescent form ; and even those arteries of the limbs which are employed on substances not muscular, branch off like the common blood-vessels. I counted 23 of these cylinders, parallel to each other, about the middle of the upper arm; and 17 in the inguinal fasci- culus. This fact appeared at first too solitary for the foundation of any physiological reasoning; but having since had an opportunity of prosecuting the inquiry among animals of similar habits and character, I have been encouraged to hope that the result may eventually assist in the elucidation of muscular motion. The bradypus tridactylus, or great American Sloth, has a similar distribution of the arteries of its limbs to that already described in the lemur tardigradus. The communications of these vessels with each other are more frequent than in the lemur tardigradus, and their number is considerably greater. I counted 42 separate cylinders on the superficies of the brachial fasciculus; and from the bulk of the fasciculus I estimate that there were 20, or more, concealed in the middle. The lower extremity has its arteries less divided, and they are of larger diameter. I observed only 34 branches in the middle of the thigh; and the first series of ramifications were larger than the subsequent ones. May not this have some relation to the greater distance of the lower limb from the heart? The extremely slow movements of the bradypus tridactylus are sufficiently known among natural historians. The bradypus didactylus has its arterial system distributed in some degree like the tridactylus; but the brachial artery in the upper limb is much less subdivided; and in the lower limb the arteries of the plexus afterwards divide a few times in the arborescent form. It may be worthy of remark, that this correspondence of arrangement, in the arteries of the lesser Sloth, bears a striking analogy with the structure and habits of the large American Sloth ; the movements of the bradypus didactylus being universally represented quicker than those of the bradypus tri- dactylus. The Lemur Loris was next examined, and its arterial system was found to resemble those already described ; but, as the animal had been preserved in very strong spirit, the vessels were so corrugated as not to admit of injection. The 2 bradypi were injected with quicksilver. The natural history of the Lemur Loris appears not to be very well ascertained; but it is a slow-moving animal, and has been confounded with the species called tardigradus, though doubtless a much more agile creature. In all the quadrupeds before mentioned, the other blood-vessels, as well as the VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 603 nerves, presented the common appearances. The size of the heads, and the in- terior capacity of the skulls, both in the bradypus tridactylus and the lemur tardi- gradus, seemed smaller in proportion than is usual among animals, so that the quantity of brain must be less than ordinary. The effect of this peculiar disposition of the arteries, in the limbs of these slow- moving quadrupeds, will be that of retarding the velocity of the blood. It is well known, and has been explained by various writers, that the blood moves quicker in the arteries near the heart, than in the remote branches; and also, that fluids move more rapidly through tubes which branch off suddenly from large trunks, than if they had been propelled for a considerable distance through small-sized cylinders; besides the frequent communications in the cylinders of the bradypus tridactylus must produce eddies, which will retard the progress of the fluid. From these and a variety of other facts, it will appear, that one effect on the animal economy, connected with this arrangement of vessels, must be, that of diminishing the velocity of the blood passing into the muscles of the limbs. It may be difficult to determine, whether the slow movement of the blood sent to these muscles be a subordinate convenience to other primary causes of their slow contraction, or whether it be of itself the immediate and principal cause. The facts at present ascertained, relative to muscular motion, do not authorize me to treat decidedly of the share which the vascular system holds in the operation of muscular contraction. Certain it is, that a larger proportion of arteries is sent to the muscles of qua- drupeds, than to the ordinary substances; and the extreme redness of these organs shows that their capillaries are of large diameter. A greater degree of redness is also observable in those muscles, of the same animal, which are most frequently called into action. The habits of life among the tardigrade animals, give occasion for the long continued contraction of some muscles in their limbs: these creatures are represented clinging to the boughs of trees, and remaining thus, without loco- motion, for several hours. The powers which require so long a time to determine the contraction of a series of muscles, are probably no less slow in restoring the parts to their former condition; or, if the restoration is to be affected by antagonist muscles under the same circumstances, then the flexion and extension of every part of the limbs will correspond, as to time. I have not met with any arrangement of blood-vessels analogous to those described, except in the carotid artery of the Lion. May not this peculiarity be subservient to the long continued exertion of the muscles of his jaws, while hold- ing a powerful animal, such as a horse or buffalo, and thus enable him to retain his prey, till it is wearied out by ineffectual struggles? I believe also, that those animals which chew the cud have a plexus of arteries in the neck, analogous to the rete mirabile: but this fact has not yet been verified in all the ruminating quadrupeds; and the effect of these arrangements seems rather to operate as sluices to the arteries of the masticating muscles, than directly as the means ot re- 4h 2 604 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. tarding the velocity of their fluids. It is however necessary to examine these subjects more accurately*. p. s. The Maucauco which Mr. John Symmons lately possessed, was sufficiently quick in the movements of its head to snap a person's finger, when touched in- cautiously; and the motion of its jaw, when chewing, was not slower than in other animals. A Maucauco of the same species, kept among the wild beasts in the Tower, was very apt to bite those who, calculating the movements of its head by those of its limbs, approached within the length of its neck : the chewing of this animal was similar to that of a cat. VII. Outlines of Experiments and Inquiries respecting Sound and Light. By Thos. Young, M. D., F. R. S. p. 106. It has long been my intention to lay before the r. s. a few observations on the subject of sound ; and I have endeavoured to collect as much information, and to make as many experiments, connected with this inquiry, as circumstances enabled me to do; but the further I have proceeded, the more widely the prospect of what lay before me has been extended ; and as I find that the investigation, in all its mag- nitude, will occupy the leisure hours of some years, or perhaps of a life, I am de- termined, in the mean time, lest any unforeseen circumstances should prevent my continuing the pursuit, to submit to the Society some conclusions which I have al- ready formed from the results of various experiments. Their subjects are, 1. The measurement of the quantity of air discharged through an aperture. 2. The de- termination of the direction and velocity of a stream of air proceeding from an orifice. 3. Ocular evidence of the nature of sound. 4. The velocity of sound. 5. Sonorous cavities. 6. The degree of divergence of sound. 7« The decay of sound. 8. The harmonic sounds of pipes. Q. The vibrations of different elastic fluids. 10. The analogy between light and sound. 11. The coalescence of mu- sical sounds. 12. The frequency of vibrations constituting a given note. 13. The vibrations of chords. 14. The vibrations of rods and plates. 15. The human voice. l6. The temparement of musical intervals. 1 . Of the quantity of air discharged through an aperture. — A piece of bladder was tied over the end of the tube of a large glass funnel, and punctured with a hot needle. The funnel was inverted in a vessel of water; and a gage, with a graduated glass tube, was so placed as to measure the pressure occasioned by the different levels of the surfaces of the water. As the air escaped through the puncture, it was supplied by a phial of known dimensions, at equal intervals of time; and according to the frequency of this supply, the average height of the gage was such as is expressed in the first table. It appears, that the quantity of air discharged by a given aperture, was nearly in the subduplicate ratio of the * There is a rete mirabie in the genus bos, and in some of the cervi which I have seen j but of these and the other pecora a fuller description will be given in a future paper. — Orig. VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 605 Table 1. A B c .00018 .25 3.9 .00018 .58 11.7 .10018 1. 15.6 .001 .045 7-8 .001 .2 15.6 .001 .7 31.2 .00* .35 46.8 A Table 2. B c .07 .07 1. 2. 2000. 2900. A B C D .0064 1.15 .2 46.8 .0064 10. .45 46.8 .0064 13.5 .35 31.2 .0064 1S.5 •7 46.8 pressure ; and that the ratio of the expenditures by different apertures, with the same pressure, lay between the ratio of their diameters and that of their areas. The 2d, 3d, and 4th tables show the result of similar experiments, made with some variations in the apparatus. It may be inferred, from comparing the ex- periments on a tube with those on a simple perforation, that the expenditure is in- creased, as in water, by the application of a short pipe. a is the area, in square inches of an aperture nearly circular, b, the pressure in inches, c, the number of cubic inches discharged in one minute. All numbers throughout this paper, where the contrary is not expressed, are to be understood of inches, linear, square, or cubic. a is the area of the section of a tube about 2 inches long, b, the pressure, c, the quan- tity of air discharged in a minute by estimation. a is the area of the section of a tube. b, its length, c, the pressure, d, the discharge in a minute. a is the area of an oval aperture, formed by flat- tening a glass tube at the end: its diameters were .025 and .152. b, the pressure, c, the discharge. 2. Of the direction and velocity of a stream of air. — An apparatus was contrived for measuring, by means of a water-gage communicating with a reservoir of air, the pressure by which a current was forced from the reservoir through a cylindrical tube; and the gage was so sensible that, a regular blast being supplied from the lungs, it showed the slight variation produced by every pulsation of the heart. The current of air issuing from the tube was directed downwards, on a white plate, on which a scale of equal parts was engraved, and which was thinly covered with a coloured liquid ; the breadth of the surface of the plate laid bare was observed at different distances from the tube, and with different degrees of pressure, gare being taken that the liquid should be so shallow as to yield to the slightest impression of air. The results are collected in tables 5 and 6, and are exhibited to the eye in plate 9, figs. 1 to 12. To measure with greater certainty and precision, the velo- city of every part of the current, a 2d cavity, furnished with a gage, was provided, and pieces perforated with apertures of different sizes were adapted to its orifice: the axis of the current was directed as accurately as possible to the centres of these apertures, and the result of the experiments, with various pressures and distances, are inserted in tables 7, 8, 9. The velocity of a stream being, both according to the commonly received opinion and to the experiments already related, nearly in the subduplicate ratio of the pressure occasioning it, it was inferred, that an equal .003 Table 4. B .28. 46.8 606 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. pressure would be required to stop its progress, and that the velocity of the current, where it struck against the aperture, must be in the subduplicate ratio of the pressure marked by the gage. The ordinates of the curves in figs. 1 3 to 23, were therefore taken reciprocally in the subduplicate ratio of the pressure marked by the 2d gage to that indicated by the first, at the various distances represented by the abscisses. Each figure represents a different degree of pressure in the first cavity. The curve nearest the axis, is deduced from observations in which the aperture opposed to the tube was not greater than that of the tube itself; and shows what would be the diameter of the current, if the velocities of every one of its particles in the same circular section, including those of the contiguous air, which must have acquired as much motion as the current has lost, were equal among themselves. As the central particles must be supposed to be less impeded in their motion than the superficial ones, of course the smaller the aperture opposed to the centre of the current, the greater velocity ought to come out, and the ordinate of the curve the smaller; but where the aperture was not greater than that of the tube, the difference of the velocities at the same distance was scarcely perceptible. When the aperture was larger than that of the tube, if the distance was very small, of course the average velocity came out much smaller than that which was inferred from a smaller aperture; but where the ordinate of the internal curve became nearly equal to this aperture, there was but little difference between the velocities indicated with different apertures. Indeed, in some cases, a larger aperture seemed to indicate a greater velocity: this might have arisen in some degree from the smaller aperture not having been exactly in the centre of the current; but there is greater reason to suppose, that it was occasioned by some resistance derived from the air returning between the sides of the aperture and the current entering it. Where this took place, the external curves, which are so constructed as that their ordinates are re- ciprocally in the subduplicate ratio of the pressure observed in the 2d cavity, with apertures equal in semidiameter to their initial ordinate, approach, for a short dis- tance, nearer to the axis than the internal curve: after this, they continue their course very near to this curve. Hence it appears, that no observable part of the motion diverged beyond the limits of the solid which would be formed by the re- volution of the internal curve, which is seldom inclined to the axis in an angle so great as 10°. A similar conclusion may be made, from observing the flame of a candle subjected to the action of a blow-pipe: there is no divergency beyond the narrow limits of the current; the flame on the contrary, is every where forced by the ambient air towards the current, to supply the place of that which it has carried away by its friction. The lateral communication of motion, very ingeniously and accurately observed in water by Professor Venturi, is exactly similar to the motion here shown to take place in air; and these experiments fully justify him in rejecting the tenacity of water as its cause: no doubt it arises from the relative situation of the particles of the fluid, in the line of the current, to that of the particles in the contiguous strata, which is such as naturally to lead to a commu- VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 607 nication of motion nearly in a parallel direction ; and this may properly be termed friction. The lateral pressure which urges the flame of a candle towards the stream of air from a blow-pipe, is probably exactly similar to that pressure which causes the inflection of a current of air near an obstacle. Mark the dimple which a slender stream of air makes on the surface of water; bring a convex body into contact with the side of the stream, and the place of the dimple will immediately show that the current is inflected towards the body ; and if the body be at liberty to move in every direction, it will be urged towards the current, in the same manner as, in Venturi's experiments, a fluid was forced up a tube inserted into the side of a pipe through which water was flowing. A similar interposition of an ob- stacle in the course of the wind, is probably often the cause of smoky chimneys. One circumstance was observed in these experiments, which it is extremely difficult to explain, and which yet leads to very important consequences: it may be made distinctly perceptible to the eye, by forcing a current of smoke very gently through a fine tube. When the velocity is as small as possible, the stream proceeds for many inches without any observable dilatation ; it then immediately diverges at a considerable angle into a cone, fig. 24; and, at the point of divergency, there is an audible and even visible vibration. The blow-pipe also affords a method of ob- serving this phenomenon: as far as can be judged from the motion of the flame, the current seems to make something like a revolution in the surface of the cone, but this motion is too rapid to be distinctly discerned. When the pressure is in- creased, the apex of the cone approaches nearer to the orifice of the tube, figs. 25, 26; but no degree of pressure seems materially to alter its divergency. The distance of the apex from the orifice is not proportional to the diameter of the current; it rather appears to be the greater the smaller the current, and is much better defined in a small current than in a large one. Its distance in one experiment is expressed in table 10, from observations on the surface of a liquid; in other experiments, its respective distances were sometimes considerably less with the same degrees of pressure. It may be inferred, from the numbers of tables 7 and 8, that in several instances a greater height of the first gage produced a less height of the 2d: this arose from the nearer approach of the apex of the cone to the orifice of the tube, the stream losing a greater portion of its velocity by this divergence than it gained by the increase of pressure. At first sight, the form of the current bears some resemblance to the vena contracta of a jet of water: but Venturi has observed, that in water an increase of pressure increases, instead of diminishing, the distance of the contracted section from the orifice. Is it not possible, that the facility with which some spiders are said to project their fine threads to a great distance, may depend on the small degree of velocity with which they are thrown out, so that, like a minute current, meeting with little interruption from the neighbouring air, they easily continue their course for a considerable time? 608 Table 5. A 1. 2. 3. 3-8 B c c c c 1. .1 .1 .1 2. .12 .12 .2 3. •17 .25 .3 4. .2 .4 .4 5. .25 .5 6. .3 .52 7- .35 .54 .5 8. •37 .56 9- •39 .58 10. .40 .6 .6 .5 15. .7 18. .50 20. PHILOSOPHICAL TRANSACTIONS. Table 7. [anno 1800. Table 6. A •• 2. B c c 1. .1 .1 2- .13 3. .2 .2 4. .25 .3 6. .3 .4 7- .35 .5 10. .35 .6' 15. .35 .7 20. .35 7 A 5 B .06 .15 C D D .1 .083 •2 .16 •3 .25 .1 •4 .35 .5 .45 .6 .53 .2 •7 .6 .8 .3 1. .5 1.2 .4 •4 1.5 .6 2. .67 .55 4. 1.3 1. 8. 2. 9. .3 14. .5 The diameter of the tube in tab. 5, is 0.7. a is the distance of the liquid from the orifice, b, the pressure, c, the diameter of the surface of the liquid displaced. In tab. 6, the diameter of the tube, .1, a, b, and c, as in tab. 5. In tab. 7, the diameter of the tube .06. a is the distance of the opposite aperture, from the orifice of the tube, b, the diameter of the aperture, c, the pressure, indi- cated by the first gage, d, the height of the second gage. Table 8. A I j .5 1. i >. A ,. 1 B .06 .15 .3 .5 .06 .15 .3 .5 .06 15. 3. 5. .06 .15 .3 .5 C D D D D D D D D D D D D D D D D .1 .05 .05 .03 .017 •2 .1 .1 .12 .08 .02 .034 .5 .2 .22 ,1 .00 .00 1. .32 .36 .1 .17 .1 .1 .05 .04 2. .52 .6 .2 .28 .22 .21 .08 ■07 3. .8 .9 .3 .4 .36 .32 .12 .12 .1 .1 4. 1.1 1.2 .4 .58 .52 .42 .16 .18 .15 .14 5. 1.5 .5 .8 .68 ■ .52 .2 .23 .2 .18 .04 .04 .05 6. 1.7 .6 1. .83 .63 .25 .3 .25 .22 .05 .05 .06 7. 19 •7 1.2 1. .75 .3 .35 .3 .26 .06 .06 •07 8. 2.1 .8 1.5 1.2 .88 .34 .4 .34 .3 •07 •07 .07 9- 2.3 •9 1.7 1.4 1. .37 .45 .37 .34 .08 .08 .08 10. 2.6 1. 1.9 1.6 1.1 .4 .5 .4 .37 .09 •09 •09 Diameter of the tube .1. a, b, c, and d, as in table 7. Table 9. A 1.15 3.3 4. B .15 .3 .5 1. .06 .15 1. .06 C D D D D D D D D .5 .1 .1 .1 1. .2 .2 .2 2. .4 .35 .34 .13 .1 .1 .125 3. .6 .5 .5 .2 .15 .15 .18 .1 Tabli . 10. A B .4 6. .8 3. 1.2 1.5 1.8 1. 2. .5 4. .0 In tab. 9, the diameter of the tube .3. a, b, c, and d, as in tab. 7. In tab. 10, a is the pressure, b the distance of the apex of the cone from the orifice of a tube, . 1 in diameter. VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 60Q 3. Ocular Evidence of the Nature of Sound. — A tube about the 10th of an inch in diameter, with a lateral orifice half an inch from its end, filed rather deeper than the axis of the tube, fig. 27, was inserted at the apex of a conical cavity containing about 20 cubic inches of air, and luted perfectly tight; by blowing through the tube, a sound nearly in unison with the tenor c was produced. By gradually increasing the capacity of the cavity as far as several gallons, with the same mouth-piece, the sound, though faint, became more and more grave, till it was no longer a musical note. Even before this period a kind of trembling was distinguishable; and this, as the cavity was still further increased, was changed into a succession of distinct puffs, like the sound produced by an explosion of air from the lips; as slow, in some instances, as 4 or 3 in a second. These were un- doubtedly the single vibrations, which, when repeated with sufficient frequency, impress on the auditory nerve the sensation of a continued sound. On forcing a current of smoke through the tube, the vibratory motion of the stream, as it passed out at the lateral orifice, was evident to the eye; though, from various circumstances, the quantity and direction of its motion could not be subjected to exact mensuration. This species of sonorous cavity seems susceptible of but few harmonic sounds. It was observed, that a faint blast produced a much greater frequency of vibrations than that which was appropriate to the cavity : a circum- stance similar to this obtains also in large organ pipes; but several minute observa- tions of this kind, though they might assist in forming a theory of the origin of vibrations, or in confirming such a theory drawn from other sources, yet, as they are not alone sufficient to afford any general conclusions, are omitted at present, for the sake of brevity. 4. On the Velocity of Sound. — It has been demonstrated, by M. De La Grange and others, that any impression whatever communicated to one particle of an elastic fluid, will be transmitted through that fluid with a uniform velocity, depending on the constitution of the fluid, without reference to any supposed laws of the conti- nuation of that impression. Their theorem for ascertaining this velocity is the same as Newton has deduced from the hypothesis of a particular law of continua- tion : but it must be confessed, that the result differs somewhat too widely from experiment, to give us full confidence in the perfection of the theory. Corrected by the experiments of various observers, the velocity of any impression trans- mitted by the common air, may, at an average, be reckoned 1 130 feet in a second. 5. Of Sonorous Cavities. — M. De la Grange has also demonstrated, that all im- pressions are reflected by an obstacle terminating an elastic fluid, with the same velocity with which they arrived at that obstacle. When the walls of a passage, or of an unfurnished room, are smooth and perfectly parallel, any explosion, or a stamping with the foot, communicates an impression to the air, which is reflected from one wall to the other, and from the 2d again towards the ear, nearly in the same direction with the primitive impulse: this takes place as frequently in a vol. xviii. 4 I 6iO PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. second, as double the breadth of the passage is contained in 1130 feet, and the ear receives a perception of a musical sound, thus determined in its pitch by the breadth of the passage. On making the experiment, the result will be found ac- curately to agree with this explanation. If the sound is predetermined, and the frequency of vibrations such as that each pulse, when doubly reflected, may coin- cide with the subsequent pulse proceeding directly from the sounding body, the intensity of the sound will be much increased by the reflection; and also in a less degree, if the reflected pulse coincides with the next but 1, the next but 2, or more, of the direct pulses. The appropriate notes of a room may readily be dis- covered by singing the scale in it; and they will be found to depend on the pro- portion of its length or breadth to 1 1 30 feet. The sound of the stopped diapason pipes of an organ is produced in a manner somewhat similar to the note from an explosion in a passage ; and that of its reed pipes to the resonance of the voice in a room : the length of the pipe in one case determing the sound, in the other, in- creasing its strength. The frequency of the vibration does not at all immediately depend on the diameter of the pipe. It must be confessed, that much remains to be done in explaining the precise manner in which the vibration of the air in an organ pipe is generated. M. Daniel Bernoulli has solved several difficult problems relating to the subject; yet some of his assumptions are not only gratuitous, but contrary to matter of fact. 6. On the Divergence of Sound. — It has been generally asserted, chiefly on the authority of Newton, that if any sound be admitted through an aperture into a chamber, it will diverge from that aperture equally in all directions. The chief arguments in favour of this opinion are deduced from considering the phenomena of the pressure of fluids, and the motion of waves excited in a pool of water. But the inference seems to be too hastily drawn : there is a very material difference between impulse and pressure; and, in the case of waves of water, the moving force at each point is the power of gravity, which, acting primarily in a perpen- dicular direction, is only secondarily converted into a horizontal force, in the direction of the progress of the waves, being at each step disposed to spread equally in every direction : but the impulse transmitted by an elastic fluid, acts primarily in the direction of its progress. It is well known, that if a person calls to another with a speaking trumpet, he points it towards the place where his hearer stands: and I am assured by a very respectable member of the r. s., that the report of a cannon appears many times louder to a person towards whom it is fired, than to one placed in a contrary direction. It must have occurred to every one's observation, that a sound such as that of a mill, or a fall of water, has appeared much louder after turning a corner, when the house or other obstacle no longer intervened; and it has been already remarked by Euler, on this head, that we are not acquainted with any substance perfectly impervious to sound. Indeed, as M. Lambert has very truly asserted, the whole theory of the speaking trumpet, supported as it is by practical experience, would fall to the ground, if it were demonstrable that VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 6*1 1 sound spreads equally in every direction. In windy weather it may often be ob- served, that the sound of a distant bell varies almost instantaneously in its strength, so as to appear at least twice as remote at one time as at another. Now if sound diverged equally in all directions, the variation produced by the wind could never exceed Tv of the apparent distance; but, on the supposition of a motion nearly rectilinear, it may easily happen that a slight change in the direction of the wind may convey the sound, either directly or after reflection, in very different degrees of strength, to the same spot. From the experiments on the motion of a current of air, already related, it would be expected that a sound, admitted at a con- siderable distance from its origin through an aperture, would proceed, with an almost imperceptible increase of divergence, in the same direction ; for, the actual velocity of the particles of air, in the strongest sound, is incomparably less than that of the slowest of the currents in the experiments related, where the beginning of the conical divergence took place at the greatest distance. Dr. Matthew Young has objected, not without reason, to M. Hube, that the existence of a condensation will cause a divergence in sound: but a much greater degree of condensation must have existed in the currents described than in any sound. There is indeed one difference between a stream of air and a sound; that, in sound, the motions of different particles of air are not synchronous: but it is not demonstrable that this circumstance would affect the divergency of the motion, except at the instant of its commencement, and perhaps not even then in a material degree; for, in general, the motion is communicated with a very gradual increase of intensity. 7. On the Decay of Sound. — Various opinions have been entertained respecting the decay of sound. M. De la Grange has published a calculation, by which its force is shown to decay nearly in the simple ratio of the distances; and M. Dan. Bernoulli's equations for the sounds of conical pipes lead to a similar conclusion. The same inference would follow from a completion of the reasoning of Dr. Helsham, Dr. Mat. Young, and Mr. Venturi. It has been very elegantly de- monstrated by Maclaurin, and may also be proved in a much more simple manner, that when motion is communicated through a series of elastic bodies increasing in magnitude, if the number of bodies be supposed infinitely great, and their difference infinitely small, the motion of the last will be to that of the first in the subduplicate ratio of their respective magnitudes; and since, in the case of con- centric spherical laminae of air, the bulk increases in the duplicate ratio of the distance, the motion will in this case be directly, and the velocity inversely, as the distance. But, however true this may be of the first impulse, it will appear, by pursuing the calculation a little further, that every one of the elastic bodies, except the last, receives an impulse in a retrograde direction, which ultimately impedes the effect of the succeeding impulse, as much as a similar cause promoted that of the preceding one: and thus, as sound must be conceived to consist of an infinite number of impulses, the motion of the last lamina will be precisely equal to that of the first; and, as far as this mode of reasoning goes, sound must decay in the 4 1 2 6l2 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. duplicate ratio of the distance. Hence it appears, that the proposal for adopting the logarithmic curve for the form of the speaking trumpet, was founded on falla- cious reasoning. The calculation of M. de la Grange is left for future examination ; and it is intended, in the mean time, to attempt to ascertain the decay of sound as nearly as possible by experiment: should the result favour the conclusions from that calculation, it would establish a marked difference between the propagation of sound and of light. 8. On the Harmonic Sounds of Pipes. — In order to ascertain the velocity with which organ pipes of different lengths require to be supplied with air, according to the various appropriate sounds they produce, a set of experiments was made, with the same mouth-piece, on pipes of the same bore, and of different lengths, both stopped and open. The general result was, that a similar blast produced as nearly the same sound as the length of the pipes would permit; or at least that the excep- tions, though very numerous, lay equally on each side of this conclusion. The particular results are expressed in table 1 1, and in fig. 28. They explain how a note may be made much louder on a wind instrument by a swell, than it can pos- sibly be by a sudden impression of the blast. It is proposed, at a future time, to ascertain by experiment, the actual compression of the air within the pipe under different circumstances; from some very slight trials, it seemed to be nearly in the ratio of the frequency of vibrations of each harmonic. a, is the length of the pipe Tablk n> from the lateral orifice to the end. c, the pressure at which the sound began, b, its ter- mination, by lessening the pressure; d, by increasing it. e, the note answering to the first sound of each pipe, ac- cording to the German method of notation, f, the number showing the place of each note in the regular series of harmo- nics. The diameter of the pipe was .35; the air duct of the mouth-piece measured, where smallest, .25 by .035; the lateral orifice .25 by .125. The apparatus was not calcu- lated to apply a pressure of above 22 inches. Where no number stands under c, a sud- den blast was required to pro- duce the note. OPEN. STOPPED. ' A B C D E F A B c D 1 F 4.5 0.7 8.8 d* 1 4.5 0.3 1.8 d 1 4.1 8.8 2 1.2 5-0 1.7 9.0 10.0 3 5 0.3 0.9 7 1 9-4 — 0.8 8.0 2 9.4 0.2 0.4 / 1 2.0 18.0 3 0.45 1.6 3 5.0 8.0 20.0 4 1.1 1.6 8.5 5 l6.5 19-0 18.0 20.0 5 6 7-0 8.0 7 16.1 0.4 0.6 d* — ; 3 16.1 0.4 1.0 g* 2 0.6 0.65 1.1 S 0.8 1.0 2.2 3 0.9 1.1 2.4 7 1.2 2.2 4.7 4 1.6 2.4 4.9 9 2.2 4.7 11.5 5 2.5 4.8 9.0 11 3.4 4.0 6.5 13.5 15.0 6 7 8 6.0 7.0 13 10.0 gg 20.5 0.8 1.1 1.1 3.8 c%& 7 9 = 1 0 20.5 0.6 0.8 b 3 1.8 3.8 11 0.8 1-9 4 3.2 3.8 12. 17 l.l 19 5.7 5 12. 0 00 4.5 5.7 8 VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 6l3 g. On the Vibrations of different Elastic Fluids. — All the methods of finding the velocity of sound agree in determining it to be, in fluids of a given elasticity, reciprocally in the subduplicate ratio of the density: hence, in pure hydrogen gas it should be s/ 13 = 3.6 times as great as in common air; and the pitch of a pipe should be a minor 14th higher in this fluid than in the common air. It is there- fore probable that the hydrogen gas used in Professor Chladni's late experiments was not quite pure. It must be observed, that in an accurate experiment of this nature, the pressure causing the blast ought to be carefully ascertained. There can be no doubt but that, in the observations of the French academicians on the velocity of sound, which appear to have been conducted with all possible attention, the dampness and coldness of the night air must have considerably increased its density: hence the velocity was found to be only 1109 feet in a second; while Derham's experiments, which have an equal appearance of accuracy, make it amount to 1 142. Perhaps the average may, as has been already mentioned, be safely estimated at 1130. It may here be remarked, that the well-known eleva- tion of the pitch of wind instruments, in the course of playing, sometimes amounting to half a note, is not, as is commonly supposed, owing to any expan- sion of the instrument, for this should produce a contrary effect, but to the in- creased warmth of the air in the tube. Dr. Smith has made a similar observation, on the pitch of an organ in summer and winter, which he found to differ more than twice as much as the English and French experiments on the velocity of sound. Bianconi found the velocity of sound, at Bologna, to differ at different times, in the ratio of 152 to 157. 10. Of the Analogy between Light and Sound. — Ever since the publication of Sir Isaac Newton's incomparable writings, his doctrines of the emanation of par- ticles of light from lucid substances, and of the formal pre-existence of coloured rays in white light, have been almost universally admitted in this country, and but little opposed in others. Leonard Euler indeed, in several of his works, has ad- vanced some strong objections against them, but not sufficiently powerful to justify the dogmatical reprobation with which he treats them ; and he has left that system of an ethereal vibration, which after Huygens and some others he adopted, equally liable to be attacked on many weak sides. Without pretending to decide positively on the controversy, it is conceived that some considerations may be brought for- wards, which may tend to diminish the weight of objections to a theory similar to the Huygenian. There are also one or two difficulties in the Newtonian system, which have been little observed. The first is, the uniform velocity with which light is supposed to be projected from all luminous bodies, in consequence of heat, or otherwise. How happens it that, whether the projecting force is the slightest transmission of electricity, the friction of 2 pebbles, the lowest degree of visible ignition, the white heat of a wind furnace, or the intense heat of the sun itself, these wonderful corpuscles are always propelled with one uniform velocity? For, if they differed in velocity, that difference ought to produce a different refraction. 6l4 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. But a still more insuperable difficulty seems to occur, in the partial reflection from every refracting surface. Why, of the same kind of rays, in every circumstance precisely similar, some should always be reflected, and others transmitted, appears in this system to be wholly inexplicable. That a medium resembling, in many properties, that which has been denominated ether, does really exist, is undeniably proved by the phenomena of electricity ; and the arguments against the existence of such an ether throughout the universe have been pretty sufficiently answered by Euler. The rapid transmission of the electrical shock shows that the electric medium is possessed of an elasticity as great as is necessary to be supposed for the propagation of light. Whether the electric ether is to be considered as the same with the luminous ether, if such a fluid exists, may perhaps at some future time be discovered by experiment; hitherto I have not been able to observe that the refrac- tive power of a fluid undergoes any change by electricity. The uniformity of the motion of light in the same medium, which is a difficulty in the Newtonian theory, favours the admission of the Huygenian; as all impressions are known to be trans- mitted through an elastic fluid with the same velocity. It has been already shown that sound, in all probability, has very little tendency to diverge: in a medium so highly elastic as the luminous ether must be supposed to be, the tendency to diverge may be considered as infinitely small; and the grand objection to the system of vibration will be removed. It is not absolutely certain, that the white line visible in all directions on the edge of a knife, in the experiments of Newton and of Mr. Jordan, was not partly occasioned by the tendency of light to diverge. Euler's hypothesis of the transmission of light, by an agitation of the particles of the refracting media themselves, is liable to strong objections; according to this suppo- sition, the refraction of the rays of light, on entering the atmosphere from the pure ether which he describes, ought to be a million times greater than it is. For explaining the phenomena of partial and total reflection, refraction, and inflection, nothing more is necessary than to suppose all refracting media to retain, by their attraction, a greater or less quantity of the luminous ether, so as to make its den- sity greater than that which it possesses in a vacuum, without increasing its elasti- city; and that light is a propagation of an impulse communicated to this ether by luminous bodies: whether this impulse is produced by a partial emanation of the ether, or by vibrations of the particles of the body, and whether these vibrations are, as Euler supposed, of various and irregular magnitudes, or whether they are uniform, and comparatively large, remains to be hereafter determined. Now, as the direction of an impulse transmitted through a fluid, depends on that of the particles in synchronous motion, to which it is always perpendicular, whatever alters the direction of the pulse, will inflect the ray of light. If a smaller elastic body strike against a larger one, it is well-known that the smaller is reflected more or less powerfully, according to the difference of their magnitudes: thus, there is. always a reflection when the rays of light pass from a rarer to a denser stratum of ether; and frequently an echo when a sound strikes against a cloud. A greater VOL XC.] PHILOSOPHICAL TRANSACTIONS. 6l5 body striking a smaller one, propels it, without losing all its motion: thus, the particles of a denser stratum of ether do not impart the whole of their motion to a rarer, but, in their effort to proceed, they are recalled by the attraction of the refracting substance with equal force; and thus a reflection is always secondarily produced, when the rays of light pass from a denser to a rarer stratum. Let ab, pi. 9. fig. 29, be a ray of light falling on the reflecting surface fg; cd the direc- tion of the vibration, pulse, impression, or condensation. When d comes to h, the impression will be, either wholly or partly, reflected with the same velocity as it arrived, and eh will be equal to dh; the angle eih to dih or cif; and the angle of reflection to that of incidence. Let pg, fig. 30, be a refracting surface. The portion of the pulse ie, which is travelling through the refracting medium, will move with a greater or less velocity in the sub-duplicate ratio of the densities, and he will be to ki in that ratio. But he is, to the radius ih, the sine of the angle of refraction ; and ki that of the angle of incidence. This explanation of refrac- tion is nearly the same as that of Euler. The total reflection of a ray of light by a refracting surface, is explicable in the same manner as its simple refraction; he, fig. 31, being so much longer than ki, that the ray first becomes parallel to fg, and then, having to return through an equal diversity of media, is reflected in an equal angle. When a ray of light passes near an inflecting body, surrounded, as all bodies are supposed to be, with an atmosphere of ether denser than the ether of the ambient air, the part of the ray nearest the body is retarded, and of course the whole ray inflected towards the body, fig. 32. The repulsion of inflected rays has been very ably controverted by Mr. Jordan, the ingenious author of a late pub- lication on the Inflection of Light. It has already been conjectured by Euler, that the colours of light consist in the different frequency of the vibrations of the lumi- nous ether: it does not appear that he has supported this opinion by any argument; but it is strongly confirmed, by the analogy between the colours of a thin plate and the sounds of a series of organ pipes. The phenomena of the colours of thin plates, require, in the Newtonian system, a very complicated supposition, of an ether, anticipating by its motion the velocity of the corpuscles of light, and thus pro- ducing the fits of transmission and reflection; and even this supposition does not much assist the explanation. It appears, from the accurate analysis of the pheno- mena which Newton has given, and which has by no means been superseded by any later observations, that the same colour recurs whenever the thickness answers to the terms of an arithmetical progression. Now this is precisely similar to the production of the same sound, by means of a uniform blast, from organ-pipes which are different multiples of the same length. Supposing white light to be a continued impulse or stream of luminous ether, it may be conceived to act on the plates as a blast of air does on the organ-pipes, and to produce vibrations regulated in frequency by the length of the lines which are terminated by the two refracting surfaces. It may be objected that, to complete the analogy, there should be tubes, to answer to the organ-pipes: but the tube of an organ-pipe is only necessary to 6l6 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. prevent the divergence of the impression, and in light there is little or no tendency to diverge; and indeed, in the case of a resonant passage, the air is not prevented from becoming sonorous by the liberty of lateral motion. It would seem, that the determination of a portion of the track of a ray of light through any homo- geneous stratum of ether, is sufficient to establish a length as a basis for colorific vibrations. In inflections, the length of the track of a ray of light through the inflecting atmosphere may determine its vibrations: but, in this case, as it is probable that there is a reflection from every part of the surface of the surround- ing atmosphere, contributing to the appearance of the white line in every direction, in the experiments already mentioned, so it is possible that there may be some 2d reflection at the immediate surface of the body itself, and that, by mutual reflec- tions between these 2 surfaces, something like the anguiform motion suspected by Newton may really take place ; and then the analogy to the colours of thin plates will be still stronger. A mixture of vibrations, of all possible frequencies, may easily destroy the peculiar nature of each, and concur in a general effect of white light. The greatest difficulty in this system is, to explain the different degree of refraction of differently coloured light, and the^separation of white light in refrac- tion: yet, considering how imperfect the theory of elastic fluids still remains, it cannot be expected that every circumstance should at once be clearly elucidated. It may hereafter be considered how far the excellent experiments of Count Rum- ford, which tend very greatly to weaken the evidence of the modern doctrine of heat, may be more or less favourable to one or the other system of light and co- lours. It does not appear that any comparative experiments have been made on the inflection of light by substances possessed of different refractive powers; undoubt- edly some very interesting conclusions might be expected from the inquiry. II. On the Coalescence of Musical Sounds. — It is surprizing that so great a ma- thematician as Dr. Smith could have entertained for a moment, an idea that the vibrations constituting different sounds should be able to cross each other in all directions, without affecting the same individual particles of air by their joint forces: undoubtedly they cross, without disturbing each other's progress; but this can be no otherwise affected than by each particle's partaking of both motions. If this assertion stood in need of any proof, it might be amply furnished by the pheno- mena of beats, and of the grave harmonics observed by Romieu and Tartini; which M. De la Grange has already considered in the same point of view. In the first place, to simplify the statement, let us suppose, what probably never precisely happens, that the particles of air, in transmitting the pulses, proceed and return with uniform motions ; and, in order to represent their position to the eye, let the uniform progress of time be represented by the increase of the absciss, and the distance of the particle from its original position, by the ordinate, fig. 33 to 38. Then, by supposing any 2 or more vibrations in the same direction to be com- bined, the joint motion will be represented by the sum or difference of the ordi- nates. When 2 sounds are of equal strength, and nearly of the same pitch, as VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 6\? in fig. 36, the joint vibration is alternately very weak and very strong, producing the effect denominated a beat, pi. 10, fig. 43, b and c; which is slower and more marked, as the sounds approach nearer to each other in frequency of vibrations; and, of these beats there may happen to be several orders, according to the peri- odical approximations of the numbers expressing the proportions of the vibrations. The strength of the joint sound is double that of the simple sound only at the middle of the beat, but not throughout its duration; and it may be inferred, that the strength of sound in a concert will not be in exact proportion to the number of instruments composing it. Could any method be devised for ascertaining this by experiment, it would assist in the comparison of sound with light. In pi. 9, fig. 33, let p and a be the middle points of the progress or regress of a particle in 2 successive compound vibrations: then, cp being = pd, kr = rn, gq= qh, and ms = so, twice their distance, 2rs = 2rn + 2nm + 2ms = kn -f- NM + nm + mo = km -f- no, is equal to the sum of the distances of the corresponding parts of the simple vibrations. For instance, if the 2 sounds be as 80 to 81, the joint vibration will be as 80.5, the arithmetical mean between the periods of the single vibrations. The greater the difference in the pitch of 2 sounds, the more rapid the beats, till at last, like the distinct puffs of air in the experiments already related, they communicate the idea of a continued sound ; and this is the fundamental har- monic described by Tartini. For instance, in pi. 9, fig. 34 — 37, the vibrations of sounds related as 1 to 2, 4 to 5, 9 to 10, and 5 to 8, are represented; where the beats, if the sounds be not taken too grave, constitute a distinct sound, which cor- responds with the time elapsing between 2 successive coincidences, or near ap- proaches to coincidence; for, that such a tempered interval still produces a har- monic, appears from pi. 9, fig. 38. But, besides this primary harmonic, a secondary note is sometimes heard, where the intermediate compound vibrations occur at a certain interval, though interruptedly; for instance, in the coalescence of 2 sounds related to each other as 7 to 8, 5 to 7, or 4 to 5, there is a recurrence of a similar state of the joint motion, nearly at the interval of T5T, -V* or -?- of the whole period; hence, in the concord of a major 3d, the 4th below the key note is heard as distinctly as the double octave, as is seen in some degree in pi. 9, fig. 35 ; ab being nearly ■§- of cd. The same sound is sometimes produced by taking the minor 6th below the key note; probably because this 6th, like every other note, is almost always attended by an octave, as a harmonic. If the angles of all the figures resulting from the motion thus assumed be rounded off, they will approach more nearly to a representation of the actual circumstances; but, as the laws by which the motion of the particles of air is regulated, differ according to the different origin and nature of the sound, it is impossible to adapt a demonstration to them all ; however, if the particles be supposed to follow the law of the harmonic curve, derived from uniform circular motion, the compound vibration will be the harmonic instead of the arithmetical mean; and the secondary sound of the interrupted vibrations will be more accurately formed, and more strongly marked, pi. 10, figs. vol. win, 4 K 6 1 8 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. 41, 42 ; the demonstration is deducible from the properties of the circle. It is remarkable, that the law by which the motion of the particles is governed, is capable of some singular alterations by a combination of vibrations. By adding to a given sound other similar sounds, related to it in frequency as the series of odd numbers, and in strength inversely in the same ratios, the right lines indicating a uniform motion may be converted very nearly into figures of sines, and the figures of sines into right lines, as in pi. 9, figs. 39, 40. 12. Of the Frequency of Vibrations contituting a given Note. — The number of vibrations performed by a given sound in a second, has been variously ascertained; first, by Sauveur, by a very ingenious inference from the beats of 2 sounds; and since, by the same observer and several others, by calculation from the weight and tension of a chord. It was thought worth while, as a confirmation, to make an experiment suggested, but coarsely conducted, by Mersennus, on a chord 200 inches in length, stretched so loosely as to have its single vibrations visible; and, by holding a quill nearly in contact with the chord, they were made audible, and were found, in one experiment, to recur 8.3 times in a second. Ey lightly pressing the chord at -f of its length from the end, and at other shorter aliquot distances, the fundamental note was found to be £ of a tone higher than the respective octave of a tuning-fork marked c : hence the fork was a comma and a half above the pitch assumed by Sauveur, of an imaginary c, consisting of I vibration in a second. 13. Of the Vibrations of Chords. — By a singular oversight in the demonstration of Dr. Brook Taylor, adopted as it has been by a number of later authors, it is asserted, that if a chord be once inflected into any other form than that of the harmonic curve, it will, since those parts which are without this figure are impelled towards it by an excess of force, and those within it by a deficiency, in a very short time arrive at or very near the form of this precise curve. It would be easy to prove, if this reasoning were allowed, that the form of the curve can be no other than that of the axis, since the tending force is continually impelling the chord to- wards this line. The case is very similar to that of the Newtonian proposition respecting sound. It may be proved, that every impulse is communicated along a tended chord with a uniform velocity ; and this velocity is the same which is in- ferred from Dr. Taylor's theorem ; just as that of sound, determined by other me- thods, coincides with the Newtonian result. But, though several late mathema- ticians have given admirable solutions of all possible cases of the problem, yet it has still been supposed, that the distinctions were too minute to be actually ob- served ; especially, as it might have been added, since the inflexibility of a wire would dispose it, according to the doctrine of elastic rods, to assume the form of the harmonic curve. The theorem of Euler and De la Grange, in the case where the chord is supposed to be at first at rest, is in effect this : continue the figure each way, alternately on different sides of the axis, and in contrary positions ; then, from any point of the curve, take an absciss each way, in the same proportion to the length of the chord as any given portion of time bears to the time of 1 semi- YOL. XC.] PHILOSOPHICAL TRANSACTIONS. 6lQ vibration, and the half sum of the ordinates will be the distance of that point of the chord from the axis, at the expiration of the time given. If the initial figure of the chord be composed of 2 right lines, as generally happens in musical instru- ments and experiments, its successive forms will be such as are represented in plate 10, figs. 47, 48 : and this result is fully confirmed by experiment. Take one of the lowest strings of a square piano-forte, round which a fine silvered wire is wound in a spiral form ; contract the light of a window, so that, when the eye is placed in a proper position, the image of the light may appear small, bright, and well defined, on each of the convolutions of the wire. Let the chord be now made to vibrate, and the luminous point will delineate its path, like a burning coal whirled round, and will present to the eye a line of light, which, by the assistance of a microscope, may be very accurately observed. According to the different ways by which the wire is put in motion, the form of this path is no less diversified and amusing, than the multifarious forms of the quiescent lines of vibrating plates, discovered by Professor Chladni ; and is indeed in one respect even more interest- ing, as it appears to be more within the reach of mathematical calculation to deter- mine it; though hitherto, excepting some slight observations of Busse and Chladni, principally on the motion of rods, nothing has been attempted on the subject. For the present purpose, the motion of the chord may be simplified, by tying a long fine thread to any part of it, and fixing this thread in a direction perpendicu- lar to that of the chord, without drawing it so tight as to increase the tension : by these means, the vibrations are confined nearly to one plane, which scarcely ever happens when the chord vibrates at liberty. If the chord be now inflected in the middle, it will be found, by comparison with an object which marked its quiescent position, to make equal excursions on each side of the axis ; and the figure which it apparently occupies will be terminated by 2 lines, the more luminous as they are nearer the ends, plate 10, fig. 49. But if the chord be inflected near one of its extremities, fig. 50, it will proceed but a very small distance on the opposite side of the axis, and will there form a very bright line, indicating its longer continuance in that place ; yet it will return on the former side nearly to the point from which it was let go, but will be there very faintly visible, on account of its short delay. In the middle of the chord, the excursions on each side the axis are always equal ; and beyond the middle, the same circumstances take place as in the half where it was inflected, but on the opposite side of the axis ; and this appearance continues unaltered in its proportions, as long as the chord vibrates at all : fully confirming the non-existence of the harmonic curve, and the accuracy of the construction of Euler and La Grange. At the same time, as M. Bernoulli has justly observed, since every figure may be infinitely approximated, by considering its ordinates as composed of the ordinates of an infinite number of trochoids of different magni- tudes, it may be demonstrated, that all these constituent curves would revert to their initial state, in the same time that a similar chord bent into a trochoidal curve would perform a single vibration ; and this is in some respects a convenient and 4k2 fj'20 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. compendious method of considering the problem. But when a chord vibrates freely, it never remains long in motion, without a very evident departure from the plane of the vibration ; and, whether from the original obliquity of the impulse, or from an interference with the reflected vibrations of the air, or from the inequa- bility of its own weight or flexibility, or from the immediate resistance of the par- ticles of air in contact with it, it is thrown into a very evident rotatory motion, more or less simple and uniform according to circumstances. Some specimens of the figures of the orbits or chords are exhibited in plate 10, fig. 44. At the middle of the chord, its orbit has always 2 equal halves, but seldom at any other point. The curves of fig. 46, are described by combining together various circular motions, supposed to be performed in aliquot parts of the primitive orbit : and some of them approach nearly to the figures actually observed. When the chord is of unequal thickness, or when it is loosely tended and forcibly inflected, the apsides and double points of the orbits have a very evident rotatory motion. The compound rotations seem to demonstrate to the eye the existence of secondary vibrations, and to account for the acute harmonic sounds which generally attend the fundamental sound. There is one fact respecting these secondary notes, which seems entirely to have escaped observation. If a chord be inflected at ±, or -£-, or any other aliquot part of its length, and then suddenly left at liberty, the harmo- nic note which would be produced by dividing the chord at that point is entirely lost, and is not to be distinguished during any part of the continuance of the sound. This demonstrates, that the secondary notes do not depend on any inter- ference of the vibrations of the air with each other, nor on any sympathetic agi- tation of auditory fibres, nor on any effect of reflected sound on the chord, but merely on its initial figure and motion. If it were supposed that the chord, when inflected into right lines, resolved itself necessarily into a number of secondary vibrations, according to some curves which, when properly combined, would ap- proximate to the figure given, the supposition would indeed in some respects cor- respond with the phenomenon related ; as the co-efficients of all the curves sup- posed to end at the angle of inflection would vanish. But whether we trace the constituent curves of such a figure through the various stages of their vibrations, or whether we follow the more compendious method of Euler to the same purpose, the figures resulting from this series of vibrations are in fact so simple, that it seems inconceivable how the ear should deduce the complicated idea of a number of heterogeneous vibrations, from a motion of the particles of air which must be extremely regular, and almost uniform ; a uniformity which, when proper precau- tions are taken, is not contradicted by examining the motion of the chord with the assistance of a powerful magnifier. This difficulty occurred very strongly to Euler; and La Grange even suspects some fallacy in the experiment, and that a musical ear judges from previous association. But, besides that these sounds are discoverable to an ear destitute of such associations, and, when the sound is produced by 2 strings in imperfect unison, may be verified by counting the number of their beats, VOL. XC.] FHILOSOPHICAL TRANSACTIONS. 621 the experiment already related is an undeniable proof that no fallacy of this kind exists. It must be confessed, that nothing fully satisfactory has yet occurred to account for the phenomena; but it is highly probable that the slight increase of tension produced by flexure, which is omitted in the calculations, and the unavoid- able inequality of thickness or flexibility of different parts of the same chord, may, by disturbing the isochronism of the subordinate vibrations, cause all that variety of sounds which is so inexplicable without them. For, when the slightest differ- ence is introduced in the periods, there is no difficulty in conceiving how the sounds may be distinguished; and indeed, in some cases, a nice ear will discover a slight imperfection in the tune of harmonic notes; it is also often observed, in tuning an instrument, that some of the single chords produce beating sounds, which un- doubtedly arise from their want of perfect uniformity. It may be perceived that any particular harmonic is loudest, when the chord is inflected at about 4- of the corresponding aliquot part from one of the extremities of that part. An observa- tion of Dr. Wallis seems to have passed unnoticed by later writers on harmonics. If the string of a violin be struck in the middle, or at any other aliquot part, it will give either no sound at all, or a very obscure one. This is true, not of inflec- tion, but of the motion communicated by a bow; and may be explained from the circumstance of the successive impulses, reflected from the fixed points at each end, destroying each other: an explanation nearly analogous to some observations of Dr. Matthew Young on the motion of chords. When the bow is applied not exactly at the aliquot point, but very near it, the corresponding harmonic is ex- tremely loud; and the fundamental note, especially in the lowest harmonics, scarcely audible : the chord assumes the appearance, at the aliquot points, of as many lucid lines as correspond to the number of the harmonic, more nearly ap- proaching to each other as the bow approaches more nearly to the point, pi. JO, fig. 51. According to the various modes of applying the bow, an immense variety of figures of the orbits are produced, fig. 45, more than enough to account for all the difference of tone in different performers. In observations of this kind, a series of harmonics is frequently heard in drawing the bow across the same part of the chord: these are produced by the bow; they are however not proportionate to the whole length of the bow, but depend on the capability of the portion of the bowstring, intercepted between its end and the chord, of performing its vibrations in times which are aliquot parts of the vibration of the chord: hence it would seem, that the bow takes effect on the chord but at one instant during each fundamental vibration. In these experiments, the bow was strung with the 2d string of a violin: and, in the preparatory application of resin, the longitudinal sound of Chladni was sometimes heard; but it was observed to differ at least a note in different parts of the string. 14. Of the Vibrations of Rods and Plates. — Some experiments were made, with the assistance of a most excellent practical musician, on the various notes pro- duced by a glass tube, an iron rod, and a wooden ruler; and, in a case where the 6'11 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. tube was as much at liberty as possible, all the harmonics corresponding to the numbers from 1 to 13, were distinctly observed; several of them at the same time, and others by means of different blows. This result seems to differ from the cal- culations of Euler and Riccati, confirmed as they are by the repeated experiments of Chladni; it is not therefore brought forward as sufficiently controverting those calculations, but as showing the necessity of a revision of the experiments. Scarcely any note could ever be heard when a rod was loosely held at its extre- mity ; nor when it was held in the middle, and struck f of the length from one end. The very ingenious method of Chladni, of observing the vibrations of plates by strewing fine sand over them, and discovering the quiescent Jines by the figures into which it is thrown, has hitherto been little known in this country: his treatise on the phenomena is so complete, that no other experiments of the kind were thought necessary. Glass vessels of various descriptions, whether made to sound by percussion or friction, were found to be almost entirely free from harmonic notes; and this observation coincides with the experiments of Chladni. 15. Of the Human Foice. — The human voice, which was the object originally pro- posed to be illustrated by these researches, is of so complicated a nature, and so imperfectly understood, that it can be on this occasion but superficially considered. No person, unless we except M. Ferrein, has published any thing very important on the subject of the formation of the voice, before or since Dodart ; his reasoning has fully shown the analogy between the voice and the voix humaine and regal organ-pipes: but his comparison with the whistle is unfortunate; nor is he more happy in his account of the falsetto. A kind of experimental analysis of the voice may be thus exhibited. By drawing in the breath, and at the same time properly contracting the larynx, a slow vibration of the ligaments of the glottis may be produced, making a distinct clicking sound ; on increasing the tension, and the velocity of the breath, this clicking is lost, and the sound becomes continuous, but of an extremely grave pitch : it may, by a good ear, be distinguished 2 octaves be- low the lowest a of a common bass voice, consisting in that case of about 2(5 vibra- tions in a second. The same sound may be raised nearly to the pitch of the com- mon voice ; but it is never smooth and clear, except perhaps in some of those per- sons called ventriloquists. When the pitch is raised still higher, the upper orifice of the larynx, formed by the summits of the arytaenoid cartilages and the epiglottis, seems to succeed to the office of the ligaments of the glottis, and to produce a re- trograde falsetto, which is capable of a very great degree of acuteness. The same difference probably takes place between the natural voice and the common falsetto : the rimula glottidis being too long to admit of a sufficient degree of tension for xery acute sounds, the upper orifice of the larynx supplies its place ; hence, taking a note within the compass of either voice, it may be held, with the same expanse of air, 2 or 3 times as long in a falsetto as in a natural voice ; hence too, the difficulty of passing smoothly from the one voice to the other. It has been remarked, that the larynx is always elevated when the sound is acute : but this elevation is only VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 02S necessary in rapid transitions, as in a shake ; and then probably because, by the contraction of the capacity of the trachea, an increase of the pressure of the breath can be more rapidly effected this way, than by the action of the abdominal muscles alone. The reflection of the sound thus produced from the various parts of the cavity of the mouth and nostrils, mixing at various intervals with the portions of the vibrations directly proceeding from the larynx, must, according to the temporary form of the parts, variously affect the laws of the motion of the air in each vibra- tion, or, according to Euler's expression, the equation of the curve conceived to correspond with this motion, and thus produce the various characters of the vowels and semi-vowels. The principal sounding board seems to be the bony palate : the nose, except in nasal letters, affords but little resonance ; for the nasal passage may be closed, by applying the finger to the soft palate, without much altering the sound of vowels not nasal. A good ear may distinctly observe, especially in a loud bass voice, besides the fundamental note, at least 4 harmonic sounds, in the order of the natural numbers ; and the more reedy the tone of the voice, the more easily they are heard. Faint as they are, their origin is by no means easy to be explained. This observation is precisely confirmed, in a late dissertation of M. Knecht, pub- lished in the musical newspaper of Leipsic. Perhaps by a close attention to the harmonics entering into the constitution of various sounds, more may be done in their analysis than could otherwise be expected. l6. Of the Temperament of Musical Intervals. — It would have been extremely convenient for practical musicians, and would have saved many warm controversies among theoretical ones, if 3 times the ratio of 4 to 5, or 4 times that of 5 to 6, had been equal to the ratio of 1 to 2. As it happens to be otherwise, it has been much disputed in what intervals the imperfection should be placed. The Aristoxe- nians and Pythagoreans were in some sense the beginners of the controversy. Sauveur has given very comprehensive tables of a great number of systems of temperament; and his own now ranks among the many that are rejected. Dr. Smith has written a large and obscure volume, which, for every purpose but for the use of an impracticable instrument, leaves the whole subject precisely where it found it. Kirnberger, Marpurg, and other German writers, have disputed with great bitterness, almost every one for a particular method of tuning. It is not with any confidence of success, that one more attempt is made, which rests its chief claim to preference, on the similarity of its theory to the actual practice of the best instrument-makers. However we estimate the degree of imperfection of 1 tempered concords of the same nature, it will appear, that the manner of dividing the temperament between them does not materially alter its aggregate sum; for instance, the imperfection of a comma in a major-third, occasions it to beat very nearly twice as fast as that of half a comma. If indeed the imperfection were great, it might affect an interval so materially as to destroy its character; as, in some methods of temperament, a minor 3d diminished by 1 commas approaches more nearly to the ratio 6 to 7> than to 5 to 6; but, with this limitation, the sum 624 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. of harmony is nearly equal in all systems. Hence, if every one of the 12 major and minor 3ds occurred equally often in the compositions which are to be performed on an instrument, it would be of no great consequence, to the sum of the imper- fections, among which of the 3ds they were divided: and even in this case the opi- nion of the best practical authors is, that the difference of character produced by a difference of proportions in various keys, would be of considerable advantage in the general effect of modulation. But when it is considered, that on an average of all the music ever composed, some particular keys occur at least twice as often as others, there seems to be a very strong additional reason for making the harmony the most perfect in those keys which are the most frequently used; since the aggre- gate sum of all the imperfections which occur in playing, must by this means be diminished in the greatest possible degree, and the diversity of character at the same time preserved. Indeed in practice this method, under different modifica- tions, has been almost universal; for though many have pretended to an equal tem- perament, yet the methods which they have employed to attain it have been evi- dently defective. It appears to me, that every purpose may be answered, by making c to e too sharp by a quarter of a comma, which will not offend the nicest ear; e to g*, and a* to c, equal; p* to a* too sharp by a comma; and the major 3ds of all the intermediate keys more or less perfect, as they approach more or less to c in the order of modulation. The 5ths are perfect enough in every system. The results of this method are shown in table 12. In practice, nearly the same effect may be very simply produced, by tuning from c to f, b*, e', g*, c*, f* 6 perfect 4ths; and c, g, d, a, e, b, f*, 6 equally imperfect 5ths, pi. 10, fig. 52. If the unavoidable imperfections of the 4ths be such as to incline them to sharp- ness, the temperament will approach more nearly to equality, which is preferable to an inaccuracy on the other side. An easy method of comparing different systems of temperament is exhibited in fig. 53, which may easily be extended to all the systems that have ever been invented. Table 12 A shows the division of a monochord corresponding to each note, in the system proposed, b, the logarithm of the temperament of each of the major 3ds. c, of the minor 3ds. n, of the 5ths; c and d being both negative. Thus I have endeavoured to advance a few steps only in the investigation of some very obscure but interesting subjects. As far as I know most of these observations are new ; but if they should be found to have been already made by any other per- c 50000 B 53224 B» 56131 A 59676 G* 63148 6 66822 F* 71041 F 74921 E 79752 %" 83810 D 89304 G* 94723 C 100000 1 C + .0013487 1 a, E — .0023603 2 G, F .0019006 2 D, B .0029122 3 D, Bfc .0024525 3 G, yjjfc .0034641 4 A, E* .0034641 4 c, C* .0044756 5 E, A* .0044756 5 F, G* .0049353 6 B, C* .0049353 6 B*, E4 .0053950 7 F* .0053950 D 1 *», G#, C*, F* - 2 F, B6, E, B 3 C, G, D, A .0000000 .0004597 .001156*2 VOL. XC.] PHILOSOPHICAL TRANSACTIONS. ()25 son, their repetition in a connected chain of inference may still be excusable. I am persuaded also, that at least some of the positions maintained are incontrover- tibly consistent with truth and nature; but should further experiments tend to con- fute any opinions here suggested, I shall relinquish them with as much readiness as I have long since abandoned the hypothesis which I once took the liberty of sub- mitting to the R. s., on the functions of the crystalline lens. Explanation of the Figures in Plates 9 and 10. — Figs. 1 — 6 ; The section of a stream of air from a tube .07 inch in diameter, as ascertained by measuring the breadth of the impression on the surface of a liquid. The pressure impelling the current, was in fig. 1, 1 inch. Fig. 2, 2. Fig. 3, 3. Fig. 4, 4. Fig. 5, 7. Fig. 6, 10. Figs. 7 — 12; A similar section, where the tube was .1 in diameter, compared with the section as in- ferred from the experiments with 2 gages, which is represented by a dotted line. From this comparison it appears, that where the velocity of the current was small, its central parts only displaced the liquid; and that where it was great, it displaced, on meeting with resistance, a surface somewhat greater than its own section. The pressure was in fig. 7, 1. Fig. 8, 2. Fig. 9, 3. Fig. 10, 4. Fig. 11, 7. Fig. 12, 10. Figs. 13 — 20; a, the half section of a stream of air from a tube .1 in diameter, as inferred from ex- periments with 2 water gages. The pressure was in fig. 13, .1. Fig. 14, .2. Fig. 15, .5. Fig 16, 1. Fig. 17, 3. Fig. 18, 5. Fig. 19, 7. Fig. 20, 10. The fine lines, marked b, show the result of the observations with an aperture .15 in diameter opposed to the stream; c with .3; and d with .5. Figs. 21 — 23; a, the half section of a current from a tube .3 in diameter, with a pressure of .5, of 1, and of 3. b shows the course of a portion next the axis of the current, equal in diameter to those represented by the last figures. Fig. 24 ; The appearance of a stream of smoke forced very gently from a fine tube. Fig. 25 and 26, the same appearance when the pressure is gradually increased. Fig. 27; see section 3. Fig. 28, the perpendicular lines over each division of the horizontal line show, by their length and distance from that line, the extent of pressure capable of producing, from the respective pipes, the harmonic notes indi- cated by the figures placed opposite the beginning of each, according to the scale of 22 inches parallel to them. The larger numbers, opposite the middle of each of these lines, show the number of vibrations ©f the corresponding sound in a second. Figs. 29 — 33; see section 10. Fig. 34, the combination of 2 equal sounds constituting the interval of an octave, supposing the progress and regress of the particles of air equable. Figs. 35, 36, 37, a similar representation of a major 3d, major tone, and minor 6th. Fig. 38, a 4th, tempered about 2 commas. Fig. 39, a vibration of a similar nature, combined with subordinate vibrations of the same kind in the ratios of 3, 5, and 7 . Fig. 40, a vibration represented by a curve of which the ordinatesare the sines of circular arcs increasing uniformly, corresponding with the motion of a cycloidal pendulum, combined with similar subordinate vibrations in the ratios of 3, 5, and 7. Figs. 41 and 42 ; Two different positions of a major 3d, composed of similar vibrations, as represented by figures of sines. Fig. 43; a contracted representation of a series of vibrations, a, a simple uniform sound, b, the beating of 2 equal sounds nearly in unison, as derived from rectilinear figures, c, the beats of 2 equal sounds, derived from figures of sines, d, a musical consonance, making by its fre- quent beats a fundamental harmonic, e, the imperfect beats of 2 unequal sounds. Fig. 44, various forms of the orbit of a musical chord, when inflected, and when struck. Fig. 45, forms of the orbit, when the sound is produced by means of a bow. Fig. 46, epitrochoidal curves, formed by combining a simple rotation or vibration with other subordinate rotations or vibrations. Figs. 47 and 48, the succes- sive forms of a tended chord, when inflected and let go, according to the construction of La Grange and Euler. Fig. 49, the appearance of a vibrating chord which had been inflected in the middle, the strongest lines representing the most luminous parts Fig. 50, the appearance of a vibrating chord, when inflected at any other point than the middle. Fig. 51, the appearance of a chord, when put in VOL. XVIII. 4 L 626 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. motion by a bow applied nearly at % of the length from its end. Fig. 52, the method of tuning recom- mended for common use. Fig. 53 ; A comparative view of different systems of temperament. The whole circumference repre- sents an octave. The inner circle l is divided into 30103 parts, corresponding with the logarithmical parts of an octave. The next circle n shows the magnitude of the simplest musical and other ratios, q is divided into 12 equal parts, representing the semitones of the equal temperament described by Zarlino, differing but little from the system of Aristoxenus, and warmly recommended by Marpurg and other late writers, y exhibits the system proposed in this paper as the most desirable ; and p the practical me- thod nearly approaching to it, which corresponds with the 11th method in Marpurg' s enumeration, ex- cept that, by beginning with c instead of b, the practical effect of the temperament is precisely inverted. k is the system of Kirnberger and Sulzer; which is derived from 1 perfect 3d, 10 perfect and 2 equally imperfect 5ths. m is the system of mean tones, the sistema participato of the old Italian writers, still frequently used in tuning organs, approved also by Dr. Smith for common use. s shows the result of all the calculations in Dr. Smith's harmonics, the system proposed for his changeable harpsichord, but nei- ther in that nor any other form capable of practical application. VIII. On the Effects which take place from the Destruction of the Membrana Tympani of the Ear. By Mr. Astley Cooper, p. 151. Anatomists have endeavoured to ascertain, by experiments on quadrupeds, the loss of power which the organ of hearing would sustain by perforating the membrana tympani: dogs have been made the subject of these trials; but the results have not been clear or satisfactory. Mr. Cheselden had conceived the design of making the human organ itself the subject of direct experiment; and a condemned criminal was pardoned, on condition of his submitting to it; but, a popular outcry being raised, the idea was relinquished. Though denied the aid of experiment, the changes pro- duced by disease frequently furnish a clue equally satisfactory. It often happens, that some parts of an organ are destroyed by disease, while other's are left in their natural state ; and hence, by the powers retained by such organ, after a partial destruction, we are enabled to judge of the functions performed by those parts when the whole was in health. Guided by this principle, I have made the human ear the subject of observation, and have endeavoured to ascertain the degree of loss it sustains in its powers by the want of the membrana tympani ; a membrane which has been generally considered, from its situation in the meatus, and its connection with the adjacent parts by a beautiful and delicate structure, as essentially necessary to the sense of hearing ; but which, as appears by the fol- lowing observations, may be lost, with little prejudice to the functions of the organ. Mr. P , a medical student aged 20, applied to me, in the winter of 1797, while he was attending a course of anatomical lectures, requesting my opinion on the nature of a complaint in his ear, which had long rendered him slightly deaf. On inquiring into the nature of the symptoms which had preceded, and of those which now accompanied the disease, he informed me, that he had been subject from his infancy to pains in the head, and was attacked, at the age of 10, with an inflammation and suppuration in the left ear, which continued discharging matter VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 6^7 for several weeks: about 12 months after the first attack, symptoms of a similar kind took place in the right ear, from which also matter issued for a considerable time. The discharge in each instance was thin, and extremely offensive to the smell ; and, in the matter, bones or pieces of bones were observable. The im- mediate consequence of these attacks was a total deafness, which continued for 3 months ; the hearing then began to return, and, in about 10 months from the last attack, was restored to the state in which it at present remains. Having thus described the disease and its symptoms, he gave me the following satisfactory proof of each membrana tympani being imperfect. Having filled his mouth with air, he closed the nostrils, and contracted his cheeks : the air, thus compressed, was heard to rush through the meatus auditorius, with a whistling noise, and the hair hanging from the temples became agitated by the current of air which issued from the ear. To determine this with greater precision, I called for a lighted candle, which was applied in turn to each ear, and the flame was agitated in a similar manner. Struck with the novelty of these phenomena, I wished to have many witnesses of them, and therefore requested him, at the conclusion of the lecture on the organ of hearing, to exhibit them to his fellow students ; with which request he was so obliging as to comply. It was evident from these experiments, that the membrana tympani of each ear was incomplete, and that the air issued from the mouth, by the Eustachian tube, through an opening in that membrane, and escaped by the external meatus. To determine the degree in which the membrana tympani had been injured, I passed a probe into each ear, and found that the membrane on the left side was entirely destroyed ; since the probe struck against the petrous portion of the tem- poral bone, at the interior part of the tympanum, not by passing through a small opening ; for, after an attentive examination, the space usually occupied by the membrana tympani was found to be an aperture, without one trace of membrane remaining. On the right side also, a probe could be passed into the cavity of the tympanum ; but here, by conducting it along the sides of the meatus, some re- mains of the circumference of the membrane could be discovered, with a circular opening in its centre, about \ of an inch in diameter. From such a destruction of this membrane, partial indeed in one ear, but complete in the other, it might be expected that a total annihilation of the powers of the organ would have followed : but the deafness was inconsiderable. This gentleman, if his attention were exerted, was capable, when in company, of hearing whatever was said in the usual tone of conversation; and it is worthy of remark, that he could hear with the left ear better than with the right, though in the left no traces of the membrana tympani could be perceived. When attending the anatomical lectures also, he could hear, even at the most distant part of the theatre, every word that was delivered ; though, to avoid the regular and constant exertion which it required, he preferred placing himself near the lecturer. I found however, that when a note was struck on the piano- forte, he could hear it only at -*-ds of the distance at which I could hear it myself; 4 l 2 ()28 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. and he informed me, that in a voyage to the East Indies, while others, when ships were hailed at sea, could catch words with accuracy, his organ of hearing received only an indistinct impression. But the most extraordinary circumstance in this case is, that the ear was nicely susceptible of musical tones ; for he played well on the flute, and had frequently borne a part in a concert. I speak this from the authority of his father, who is a judge of music, and plays well on the violin : he told me, that his son, besides playing on the flute, sung with taste, perfectly in tune. The slight degree of deafness of which Mr. P complained, was always greatly increased by his catching cold : an effect which seems to have arisen from the meatus being closed by an accumulation of the natural secretion of the ear ; for it frequently happened to him, after he had been some time deaf from cold, that a large piece of hardened wax, during a fit of coughing, was forced from the ear, by the air rushing from the mouth through the Eustachian tube, and his hearing was instantly restored. From bathing too, he suffered inconvenience, unless his ears were guarded against the water, by cotton being previously forced into the meatus. When this precaution was neglected, the water, as he plunged in, by rushing into the interior parts of the ears, occasioned violent pain, and brought on a deafness, which continued till the cause was removed, that is, till the water was discharged : but he had acquired the habit of removing it, by forcing air from the mouth through the ear. In a healthy ear, when the meatus auditorius is stopped by the finger, or is otherwise closed, a noise similar to that of a distant roaring of the sea is produced : this arises from the air in the meatus being compressed on the membrana tympani. In the case here described, no such sensation was produced : for, in Mr. P.'s ear, the air, meeting with no impediment, could suffer no compression; since it found a passage, through the open membrane, to the mouth, by means of the Eustachian tube. Mr. P was liable to the sensation commonly called the teeth being on edge, in the same degree as it exists in others ; and it was produced by similar acute sounds, as by the filing of a saw, the rubbing of silk, &c. Its occurring in him seems to disprove the idea which has been entertained of its cause ; for it has been thought, that the close connection of the nerve called the chorda tympani with the membrana tympani, exposed it to be affected by the motions of the malleus ; and that, as it passes to nerves connected with the teeth, they would suffer from the vibratory state of the nerve, produced by the agitations of the membrane. But in this case, as the membrane was destroyed on that side on which the sensation was produced, some other explanation must be resorted to ; and 1 see no reason why this effect should not be referred to that part of the auditory nerve which lines the labyrinth of the ear, which, being impressed by acute and disagreeable sounds, would convey the impression to the portio dura of the same nerve, and to the teeth with which that nerve is connected. The external ear, though 2 distinct muscles are inserted into it, is capable, in its natural state, of little motion ; however, when VOL. XC.l PHILOSOPHICAL TRANSACTIONS. 629 an organ becomes imperfect, every agent which can be employed to increase its powers is called into action ; and, in the case here described, the external ear had acquired a distinct motion upward and backward, which was observable whenever Mr. P listened to any thing which he did not distinctly hear. This power over the muscles was so great, that when desired to raise the ear, or to draw it back- wards, he was capable of moving it in either direction. This case is not the only one of this description which has come under my ob- servation ; for another gentleman, Mr. A — , applied to me under a similar com- plaint, but in one ear only, proceeding from suppuration, and producing the same effects. This gentleman has the same power of forcing air through the imperfect ear; suffers equally from bathing, if the meatus auditorius be unprotected; and feels, even from exposure to a stream of cold air, very considerable pain. The only difference I could observe was, that in Mr. A.'s case, the defect of hearing in the diseased organ was somewhat greater than in the former ; for though, when his sound ear was closed, he could hear what was said in a common tone of voice, yet he could not distinguish the notes of a piano-forte at the same distance: a difference which might have in part arisen from the confused noise which is always produced by closing the sound ear ; or because, as he heard well on one side, the imperfect ear had remained unemployed, and consequently had been enfeebled by disuse. From these observations it seems to follow, that the loss of the membrana tympani in both ears, far from producing total deafness, occasions only a slight diminution of the powers of hearing. Anatomists who have destroyed this mem- brane in dogs, have asserted, that at first the effect on the sense of hearing was trivial ; but that after a few months a total deafness ensued. Haller also has said, that if the membrane of the tympanum be broken, the person becomes at first hard of hearing, and afterwards perfectly deaf. But in these instances the destruction must have extended further than the membrana tympani ; and the labyrinth must have suffered from the removal of the stapes, and from the consequent discharge of water contained in the cavities of the internal ear ; for it has been very constantly observed, that when all the small bones of the ear have been discharged, a total deafness has ensued. It is probable, that in instances in which the membrana tympani is destroyed, the functions of this membrane have been carried on by the merrflbranes of the fenestra ovalis and fenestra rotunda : for as they are placed over the water of the labyrinth, they will, when agitated by the impressions of sound, convey their vibrations to that fluid in a similar manner, though in somewhat an inferior degree, to those which are conveyed by means of the membrana tympani and the small bones which are attached to it; and thus, in the organ of hearing, each part is admirably adapted, not only to the purpose for which it is designed, but also as a provision against ac- cident or disease; so that, whenever any particular part is destroyed, another is substituted for it, and the organ, from this deprivation, surfers but little injury in its functions. It seems that the principal use of the membrana tympani is, to modify 630 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. the impressions of sound, and to proportion them to the powers and expectation of the organ. Mr. P — had lost this power for a considerable period after the de- struction of the membrane ; but in process of time, as the external ear acquired the additional motions I have described, sounds were rendered stronger or weaker by them. When therefore he was addressed in a whisper, the ear was seen immedi- ately to move ; but when the tone of voice was louder, it then remained altogether motionless. Some additional Remarks to the foregoing, on the Mode of Hearing in Cases where the Membrana Tympani has been destroyed. By Evd. Home, Esq. p. 159. After having communicated to the r. s. the curious facts contained in Mr. Cooper's paper, which prove that the organ of hearing is capable of receiving all the different impressions of sound, when the membrana tympani has been destroyed, it may not be improper to explain, from the observations contained in a former paper on this subject, in what manner this may take place. It is there stated, that any vibrations communicated directly to the bones of the skull, are as accurately im- pressed on the organ, as through the medium of the membrana tympani. The office of that membrane is therefore to afford an extended surface, capable of re- ceiving impressions from the external air, and of communicating them to the small bones of the ear ; which a membrane would be incapable of doing, unless it had a power of varying its tension, to adapt it to different vibrations. In the above cases, in which this membrane, the malleus, and the incus, had been destroyed, it would appear that the stapes was acted on by the air received into the cavity of the tympanum, and communicated the impressions immediately to the internal organ. This not happening for some months after the membrane was de- stroyed, probably arose from the inflammation of the tympanum confining the stapes, and rendering its vibrations imperfect. That sounds can be communicated with accuracy by the bones of the skull, to the internal organ, when received from solid or liquid substances, has long been well understood. That the membrana tympani is incapable of perfectly answering this purpose, when sounds are propa- gated through air, has been a generally received opinion ; to refute which, was the object of my former paper. That in cases in which the membrana tympani has been destroyed, the air is capable of acting with sufficient force on the stapes to communicate vibrations to it, and to produce on the internal organ the necessary effect for perfect hearing, is completely ascertained by Mr. Cooper's observations. IX. Experiments and Observations on the Light which is Spontaneously emitted, ivith some Degree of Permanency, from various Bodies. By Nath. Hulme,* M. D., F.R.S. and A.S. p. 161. The discoveries which have been made with respect to light, as it proceeds im- * Dr. Hulme was a native of Yorkshire, where he was born, in 1732 j and he died in the Charter- VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 631 mediately from the sun, are many and important ; but the observations on that species of light which is spontaneously emitted from various bodies, are not only few in number, but in general very imperfect. The author is therefore desirous of drawing the future attention of the philosopher more particularly to this subject, and of communicating his own experiments and observations on it, to the r. s. By the spontaneous emission of this light, the author wishes to distinguish it from atf kinds of artificial phosphorus ; which, as he apprehends, differ essentially, in some of their properties, from that light of which he means to treat. And, by its ad- hesion to bodies with some degree of permanency, he distinguishes it from that transient sort of light which is observable in electricity, in meteors, and in other lucid emanations. The light which is the subject of this paper, he therefore dis- criminates by the name of spontaneous light. The substances from which such light is emitted, are principally the following. Marine animals, both in a living state, and when deprived of life. As instances of the first may be mentioned, the shell-fish called pholas, the medusa phosphorea, and various other mollusca. When deprived of life, marine fishes in general seem to abound with this kind of light. The hon. Mr. Boyle commonly obtained light, for his use, from the whiting, as appears from many parts of his works : Dr. H. pro- cured his fish light chiefly from the herring and the mackerel. The flesh of qua- drupeds has also been observed to emit light. Instances of this are mentioned by Fabricius ab Aquapendente ; by T. Bartholin ; by Mr. Boyle ; and by Dr. Beale ; for which, see T. Bartholin, de luce animalium, p. 183; Boyle's works, vol. 3, p. 304 ; Phil. Trans, vol. 1 1, p. 5QQ. In the class of insects are many which emit light very copiously, particularly several species of fulgora or lantern-fly, and of lampyris or glow-worm; also the scolopendra electrica; and a species of crab, called cancer fulgens. Rotten wood is well known to emit light spontaneously. Peat earth also has the same property. Of the effects of the latter, a remarkable instance is related in Plot's Nat. Hist, of Staffordshire, p. 115. The place where the following experiments were made, was a dark wine-vault, which, for distinction's sake, the author calls the laboratory. The heat of this la- boratory varied, throughout the year, from about 40 degrees of temperature to 64°. The thermometer made use of was that of Fahrenheit. The weight is always to be supposed that called Troy weight. The liquid measure employed, was that used for wine in this country : the ounce containing 8 dr. avoirdupois ; and the pint, house, London, in 1807. It would seem that he studied physic at Edinburgh, as we find published there an inaugural dissertation, " DeScorbuto," 176*5, afterwards reprinted in 1768, both in Latin and English. He published also a treatise on the Puerperal Fever, Lond. 1772. Dr. H. practised medicine during a long course of years in London, with considerable reputation, and was elected physician to the Charter- house, in 1774, which appointment he held to the time of his death. He lost his life in consequence of the chimney of his house being blown down ; when, getting up through the trap-door to the roof, to see what damage had been done, he fell from the steps, so as to cause a violent concussion of the brain> which in a few days terminated fatally. 632 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. 16 oz. The water used in general for the experiments, was pure spring water, drawn up from under ground by means of a pump ; and it was always employed cold, unless otherwise expressed. Section 1 . The Quantity of Light emitted by Putrescent Animal Substances, is not in Proportion to the Degree of Putrefaction in such Substances as is com- monly supposed ; but, on the contrary, the greater the Putrescence, the less is the Quantity of Light emitted. The truth of this proposition is proved by 7 different experiments, made partly on dead herrings and partly on dead mackerel. The light which they emitted dimi- nished after the 2d or 3d day, and was nearly extinct on the 4th or 5 th day. n. b. In experiments of this kind, for the production of light, the fishes should always be gutted, the roes taken out ; and the scales, if any, carefully removed. As the roes are likewise very productive of light, they should be preserved. Obser. 1 . These experiments clearly prove, that light begins to be emitted by marine fishes, before any signs of putrefaction appear: they likewise demonstrate, that as soon as a great degree of putrescence has taken place, the luminous pro- perty of the fishes is destroyed, and the light extinguished. Obser. 2. In the instance of light proceeding spontaneously from animal flesh, recorded by Aquapendente, the flesh emitted light before any sensible putrescence had taken place, the meat being hung up in the larder for use. In that also men- tioned by Bartholin, in l641, the flesh must have been fresh and sweet, for it was not intended to be dressed till the next day. Mr. Boyle, in his report of light issuing from flesh, expressly says, that neither he, nor any of those who were about him, could perceive in it any offensive smell, whence to infer any putrefac- tion; the meat being judged very fresh, and well conditioned, and fit to be dressed. And lastly Dr. Beale, in his account of a luminous neck of veal, says, that when it was dressed, on Feb. the 27th, some of the neighbours, who saw it shining, were invited to eat of it, and all esteemed it as good as they had ever tasted; that a part of it was kept for Feb. 28th and 29th, in which time it lost nothing of its sweetness. Obser. 3. Whenever I wish to obtain a plentiful supply of light from fishes, for the purpose of experiments, I always endeavour to procure the freshest that can be had: long experience and frequent disappointments have taught me to adopt such a precaution. Section 2. The Light here treated of is a constituent Principle of some Bodies, particularly of Marine Fishes, and may be separated from them, by a peculiar Process ; may be retained, and rendered permanent for some Time. It seems to be incorporated with their whole Substance, and to make a Part of it, in the same manner as any other constituent Principle. Exper. 1. A fresh herring was split, or divided longitudinally, by a knife, into 2 parts. Then, about 4 dr. of it, being cut across, were put into a solution, com- posed of 2 dr. of Epsom salt or vitriolated magnesia, and 2 oz. of cold spring water VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 633 drawn up by the pump. The liquid was contained in a wide-mouthed 3 oz. phial, which was placed in the laboratory. On carefully examining the liquid, on the 2d evening after the process was begun, I could plainly perceive a lucid ring (for the phial was round) floating at the top of the liquid, the part below it being dark; but on shaking the phial, the whole at once became beautifully luminous, and con- tinued in that state. On the 3d evening, the light had again risen to the top; but the lucid ring appeared less vivid, and on shaking the phial as before, the liquid was not so luminous as on the preceding night. — Exper. 2. The same expe- riment was repeated. On the 2d night, the liquid, being agitated, was very lumi- nous; on the 3d, not so lucid; and on the 4th the light was extinguished. — Exper. 3. With sea salt or muriated natron \ dr., and 2 oz. of water. On the 2d night, the liquid, when agitated, was dark ; on the 3d, lucid ; on the 4th, very luminous; on the 5th, it began to lose light; on the 6th, it continued to decrease; and on the 7th it was quite gone. Neither the liquid, nor the herring, had con- tracted any putrid smell. Exper. 4. With sea-water 2oz. -On the 2d night, dark ; on the 3d, 4th, and 5th, luminous ; on the 6th, nearly extinct ; and on the 7th, totally. The piece of herring, when taken out and examined, was re- markably sweet. Exper. 5. Roe of herring,* with Epsom salt 2 dr., and water 2oz. On the 2d night, the liquid was pretty luminous ; on the 3d and 4th, still luminous ; and on the 5th its light was extinct — .Exper. 6. With Glauber's salt or vitriolated natron 2 dr., to 2 oz. of water. On the 2d night, when the phial was shaken,, as usual in all these experiments, the liquid was pretty luminous ; on the 3d, less so ; and on the 4th the light was scarcely visible. — Exper. 7 . With sea-water 2 oz. On the 2d night, dark ; on the 3d, the liquid was moderately luminous ; on the 4th and 5th, it had extracted much light ; and on the 7th it was still shining. After this process, both the roe and the sea-water remained perfectly sweet. The Flesh of Mackerel. — Exper. 8. With Epsom salt 2 dr., and water 2 oz. On the 2d night, the liquid was finely illuminated ; on the 3d, a similar appear- ance; on the 4th, a diminution of light; on the 5th, it continued lucid in a small degree ; and on the 6th the light was extinguished. Roe of Mackerel. — Exper. Q. With Epsom salt 2 dr., and water 2 oz. On the 2d night, the liquid, when agitated, was exceedingly bright ; on the 3d, the same ; and on the 4th and 5th, still lucid. The Tadpole. — Exper. 10. It occurred to my mind, in 1797, to try what effect a saline menstruum would have on the tadpole. Accordingly, I procured some tadpoles on the 10th of June, and put 6 of them into a solution of 2 dr. of Glau- ber's salt in 2 oz. of water. On the 11th, in the evening, the menstruum was dark; on the 12th, after shaking the phial, I was agreeably surprized to find it impregnated with light ; on the 13th, the light was so abundant as to float on the top of the menstruum ; on the 14th, the same phenomenon appeared ; on the * The quantity used in each experiment was about i drams.— Orig. VOL. XVIII. 4 M 634 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. 15th and l6th, it was still present; on the 17th, the lucidness began to diminish; on the 18th, it was faint; and on the 19th it had vanished. — Exper. 11. June 11th, 6 other tadpoles were dropped into a solution of 1 dr. of common salt in 3 oz. of water. On the 12th and 13th, the menstruum was dark; on the 14th, it had extracted from the tadpoles a very beautiful bright light; on the 15th, the menstruum was exceedingly luminous; on the 16th and 17th, nearly the same: the light then gradually faded, so that on the 21st it was merely visible; and on the 22d it disappeared. — Exper. 12. On the 21st of June, the above 2 experiments were repeated; when the tadpoles remained in the menstruums till the 27th, but no light was emitted. What was the cause of this failure in these 2 last experi- ments ? Was it 10 days' increased growth of the animal, which was taken from the same pond, that made the difference ? — Exper. 13. The above experiments were repeated, when the tadpole had just put on the state of a frog, but without producing any lucid appearance. The Light is incorporated with the whole Substance of Marine Fishes. Exper. 14. A fine fresh herring, being gutted, was divided longitudinally into 2 parts, both of which were hung up, by pieces of string, in the laboratory. On the 2d night, they were very lucid on the skinny side, but not on the fleshy or inward part; on the 3d, the fleshy or central parts of the fish were thickly covered with a rich azure light ; on the 4th, they continued exceedingly luminous; and on the 5th and 6th they were still lucid. It is surprizing to think what a profusion of light was emitted from the interior substance of this single fish. — Exper. 15. A similar experiment was made with a mackerel, and with similar effects. These 2 experiments were frequently repeated. — Exper. 16. But the soft-roe, of both the herring and the mackerel, abounds more with light than even the flesh. When it is in its most luminous state, which generally happens about the 3d or 4th night, it wiH sometimes shine so very splendidly, as to appear like a complete body of light. It is remarkable that the hard-roe in general does not emit so much light as the soft-roe. When the roes were used, they were laid on plates, and deposited in the laboratory. Obser. 1. The above experiments clearly prove, as I apprehend, that this light is a constituent principle of marine fishes : and that it is separated, by the men- struum employed on this occasion, in the same way that the principles of any other body are separated, by the menstruum fitted to decompose it. They like- wise show, that it is not partially but wholly incorporated with every part of their substance, and makes a part of it, in the same manner as any other constituent principle. Obser. 2. Light is probably the first constituent principle that escapes, after the death of marine fishes. The experiments of the first $. teach us that it appears soon after death, even in fishes which, to the eye, seem quite fresh and sweet ; or at least long before any sensible putrescence takes place. And we have seen that VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 635 the flesh and roes, infused in the saline menstruums, continued to emit light for several days, without undergoing any apparent putrefactive change. Obser. 3. The experiments likewise render it probable, that no offensive putre- faction takes place in the sea, after the death of such myriads of animals as must needs daily perish in the vast ocean, quite contrary to what happens on land ; and that the flesh of marine fishes remains pretty sweet for some time, and may become wholesome food for many kinds of those which still remain alive. An eminent instance this, of the wisdom of the Creator, in the construction of the aqueous part of the world, which comprehends, by far, the greatest portion of the terra- queous globe, and is the most replete with animal life ! Section 3. Some Bodies or Substances have a Power of extinguishing spontaneous Light, when it is applied to them. Expers. The luminous matter proceeding from the herring and the mackerel, was quickly extinguished when mixed with the following substances: 1. Water alone. 2. Water impregnated with quick-lime. 3. Water impregnated with car- bonic acid gas. 4. Water impregnated with hepatic gas. 5. Fermented liquors. 6. Ardent spirits. 7. Mineral acids, both in a concentrated and diluted state. 8. Vegetable acids. Q. Fixed and volatile alkalis, when dissolved in water. ]0. Neutral salts : viz. saturated solutions of Epsom salt, of common salt, and of sal ammonia. 1 1 . Infusions of chamomile flowers, of long pepper, and of cam- phor, made with boiling-hot water, but not used till quite cool. 12. Pure honey, if used alone. Section 4. Other Bodies or Substances have a Power of preserving spontaneous Light for some Time, when it is applied to them. Eocper. 1 . Some luminous matter scraped from the herring, was mixed with a solution of 2 dr. of Epsom salt in 2oz. of cold pump water: after shaking very well for some time the phial which contained them, the whole liquid became richly impregnated with light, and continued shining above 24 hours. This experiment was frequently repeated, and with the same effect. — Exper. 2. Two dr. of Glau- ber's salt and 2 oz. of water being mixed with herring light, the solution was quickly made very lucent, and remained so till the succeeding evening. — Exper. 3. Mackerel-light, being mixed with 2 dr. of Rochelle salt or tartarized natron, and 2 oz. of water, caused the fluid to be very luminous. — Exper. 4. Two dr. of soda phosphorata and 2 oz. of water, mixed with herring-light, formed a very lucent fluid, which retained the light for a long time. — Exper. 5. Herring-light, with 1 dr. of saltpetre or nitrated kali, and 2 oz. of water, made the solution pretty luminous. — Exper. 6. Half a dr. of common salt dissolved in 2 oz. of water, with the addition of mackerel-light, composed a very shining mixture, which retained its splendour for the space of a day or 2. The same effect was produced by herring light. — Exper. 7. Two oz. of sea-water, being agitated with the light of a mackerel, soon obtained a brilliant illumination. The sea-water preserved its luminousness for several days. The experiment was successfully repeated. — Exper. 4 m 2 636 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. 8. Two dr. of pure honey, that had not been clarified, or exposed to heat were dissolved in 2 oz. of water ; and, after the admission of some mackerel-light and shaking the phial, the solution was fully impregnated with light, which was visible the next evening. — Exper. Q. Two dr. of purified or refined sugar being dissolved in 2 oz. of water, and mixed with the shining matter of a herring, the fluid ac- quired a great degree of lucidness. The same effect took place when the experi- riment was made with soft brown sugar. Obser. These experiments enable us to take light, and diffuse it through water so as to render the whole liquid most brilliantly luminous, or in other words to impregnate water with light. By these means, the light is so extended in its sur- face, and combined in such a manner, as to become exceedingly convenient and useful for various other experiments. Section 5. When spontaneous Light is extinguished by some Bodies or Substances it is not lost, but may be again revived in its former Splendour, and that by the most simple Means. Exper. 1. June 1, 1795, the following experiments were made, to know what was the best proportion of Epsom salt to water, in order to produce the most luminous liquid. Some shining matter was taken from a mackerel, and mixed with a solu- tion of 7 dr. of the salt in 1 oz. of water; and its light was immediately extin- guished. The same effect ensued, but in a less degree, with a solution of 6 and one of 5 dr. In a solution of 2 dr., in the same quantity of water, the liquid was luminous ; but much more so when only I dr. of salt was used. Observing the extinction of light to take place, as above, in the more saturated solutions, while the diluted solutions were luminous, it occurred to endeavour to discover what became of the extinguished light, in the former case, and whether it might not be revived by dilution. For this purpose, I took the solution of 7 dr. of salt in 1 oz. of water, in which the lucid matter from a mackerel had been extinguished, and diluted it with 6 oz. of cold pump water; when, to my great astonishment, light in a moment burst out of darkness, and the whole liquid became beautifully luminous ! This revived light remained above 48 hours, that is, as long as other light in general does, which has never been extinguished. Hence, it had lost nothing of its vivid luminous powers by its extinction. — Exper. 2. The last expe- riment was then reversed. A solution of 1 dr. of Epsom salt in 1 oz. of water, was brilliantly illuminated with mackerel light. Then, 6 dr. of the salt were put into this luminous liquid ; and after shaking the phial very well for a little time, to promote the solution of the salt, the light was totally extinguished. But the same light was again recovered by the addition of 6 oz. of water. In this manner the light may be frequently extinguished, and as often revived. In one instance, the same light, by a repetition of this method, was made to undergo 1 0 extinctions. — Exper. 3. A good quantity of herring-light being mixed with a solution of 4 dr. of common salt, in 2 oz. of water, was immediately extinguished. Then 14 oz. of cold pump water were added ; when the whole liquid was at once finely illumi- VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 637 nated. The next evening it appeared still very lucid ; as also on the succeeding night. — Exper. 4. The experiment was reversed. Half a dr. of the salt being dis- solved in 2 oz. of water, had herring-light mixed, so as to be made very luminous. On the addition of 2 dr. more of the salt, the lucidness was instantly destroyed ; but the light was again recovered, by pouring 8 oz. of cold water on the extin- guished luminous fluid. The revived light was very vivid the next evening. — Exper. 5. Two oz. of sea-water were illuminated with mackerel-light, and then extinguished by adding 2 dr. of common salt. The light was again restored, by diluting the solution with 8 oz. of cold spring water. n. B. If the illuminated liquid be uncommonly brilliant, it may sometimes require more salt to extinguish the light completely, than is here specified ; in that case, the measure of water for dilution must be always calculated in exact propor- tion to the weight of salt employed. Section 6. Spontaneous Light is rendered more vivid by Motion. The truth of this proposition is proved by 2 experiments in which the liquid became more luminous on being shaken or stirred. Section 7. Spontaneous Light is not accompanied with any Degree of sensible Heat, to be discovered by a Thermometer. The truth of this proposition is proved by 5 different experiments made on dead herrings, dead mackerel, rotten wood, &c. Section 8. The Effects of Cold on Spontaneous Light. The Light of Fishes. — Exper. 1. Five small gallipots, containing 3 pieces of soft-roe of herring, and 2 of the herring itself, all very luminous, were placed in a frigorific mixture, composed of snow and sea-salt ; in about an hour and a half the light was quite extinct, and the bodies totally frozen. The gallipots were then removed into a vessel of cold water, that their contents might be gradually thawed; which being done, they all recovered their pristine luminous state. The pieces were afterwards observed to shine during 3 succeeding nights. — Exper. 2. A small phial, containing 3 or 4 drams of liquid impregnated with light, was placed in a frigorific mixture. As the liquid froze, its lucidness gradually diminished ; and when it quit© congealed the light perfectly disappeared. The phial was then taken out, and put into cold water, at about 49° temperature, that the ice might be gra- dually liquified ; after which, the whole fluid became as luminous as before. The Light of shining Wood. — Exper. 3. A fragment of shining wood was put into a small wide-mouthed phial, which was plunged into a frigorific mixture. As the cold affected the wood, the light gradually faded, and at last was totally im- perceptible. The phial was then taken out, and placed in water at about 62° ; by this change of temperature, the frozen wood gradually thawed, and then regained its former lustre. The Light of Glow-worms. — Exper. 4. A small phial, containing a luminous dead glow-worm, was exposed to the cold of the frigorific mixture ; as the cold- ness penetrated the phial, the light diminished, and at length was totally extinct. 638 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. But, by placing the phial in water at about 620, the glowing property of the insect soon returned. In this experiment, the glow-worm was evidently congealed ; for it adhered to the side of the glass, and was covered with a hoar-frost. This expe- riment was frequently repeated, and with the same result. Obser. By these experiments we learn, that cold extinguishes spontaneous light in a temporary manner, but not durably, as the substances of the 3d ^. do ; be- cause the light revived again in its full splendour, as soon as it was exposed to a moderate temperature. Section 9. The Effects of Heat on Spontaneous Light. The Light of Fishes. — Exper. 1. One side of a luminous herring was held before the fire, for a short space of time, but so as to receive its heat very strongly. It was then conveyed into the laboratory ; when that side which had been exposed to the fire was found quite dark, but the other continued still luminous. The fish was preserved till the next evening, but the extinguished light did not re-appear. — Exper. 2. A whole herring, finely shining, was thrown into a quantity of boiling- hot water, and the light was immediately extinguished: after keeping it there for some time, it was taken out, but the light did not revive. The Light of shining Wood. — Exper. 3. A piece of shining wood, its light being very faint, was put into tepid water at about go degrees of temperature, and it became in a short time much more lucid. Another piece, at 960, was rendered beautifully luminous. — Exper. 4. A pretty thick piece of shining wood was put into a gallipot, and sunk under water by means of a weight, together with a ther- mometer, at the temperature of 64°. Boiling-hot water was then added by spoon- fuls; and the light, at first, was rendered much mere vivid, but soon after began to decrease, and was apparently extinct at about 110°. I say apparently, because on the next evening the light had somewhat revived; which shows, that the heat of 110° was not sufficient to extinguish totally all the light inherent in this piece of wood. — Exper. 5. Finding that 1 10° of heat did not wholly extinguish the light of shining wood, a good many fragments, of different sizes, were then submitted to the power of boiling water, and detained therein for some time, in order that the heat might penetrate them thoroughly. The effect was, that the light became quickly extinct, and did not, as before, re-appear on the following evening. The Light of Glow-worms. — Exper. 6. A dead shining glow-worm was put on 2 ounces of water, contained in a wide-mouthed phial, at the temperature of 58°. The phial was then sunk, about 2 or 3 inches deep, in boiling-hot water; and, as the heat communicated itself to the contents of the phial, the light of the glow-worm became much more vivid. — Exper. 7 . Another lucid dead glow- worm was put into warm water, at 114°, to see if that degree of heat would ex- tinguish the light; but, on the contrary, its glowing property was augmented. All the water was then poured off, yet the insect continued to shine for some length of time. — Exper. 8. The effect of that heat which is obtained from dry solid bodies by friction, was next tried on the light of the glow-worm. Two VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 639 living glow-worms were put into a one-ounce phial, with a glass stopple; and though they were perfectly dark at the time, yet, if the phial was briskly rubbed with a silken or linen handkerchief, till it became pretty warm, it seldom failed to make them display their light very finely. This experiment was very frequently repeated. It had the same illuminating effect on the light of a dead glow-worm. — Exper. Q. The complete influence of 212 degrees of heat was now applied to the light of a glow-worm, by pouring on one when dead, but in a luminous state, some boiling water. Its light was instantly extinguished, and did not revive. The experiment was repeated, and with the same result. Any of the saline Solutions mentioned in the 4 th Section, being impregnated with luminous matter, and left some time at rest, are rendered more lucid by a mo- derate Degree of Heat. This is proved by 3 different experiments. Their Light is extinguished by a great Degree of Heat. This is also proved by 3 separate experiments. The luminous property was destroyed by a degree of heat from q6 to 100. If much Heat be applied to the Bottom of a Tube filled with illuminated Liquid, which has been some Time at rest, the Light will descend in luminous Streams, from the Top of the Tube to the Bottom, and be gradually extinguished. Exper. 10*. A glass cylindrical tube, closed at one end, being 9 inches long, with a bore of l^V inch, when used, was put into a gallipot 34- inches deep, and 3-|- wide, which held about 12 oz. of boiling water, and was placed in another larger vessel, to receive the overflowing water on the immersion of the tube. The tube being filled over night with some very luminous liquid, was placed in the laboratory till the next evening. The light had then ascended plentifully to the top of the fluid, the rest being dark, and, taking the circular shape of the tube, formed a very lucid ring. The vessels with the boiling-hot water were then carried into the dark laboratory; and the tube being gently and carefully placed, without shaking, in the gallipot, the light was, generally in about -§- a minute, seen plainly to descend in streams from the top to the bottom, illuminating the whole fluid in its descent in a beautiful manner, and then was gradually extinguished. The ex- tinction of the light began at the top of the tube, and ended at the bottom. — Exper. 17. The experiment was also made with a tube 19 inches high, 4- an inch in bore, having several curvatures, and sealed hermetically at its lower end. Both the extremities were made straight for a few inches; the one to be immersed in the water, and the other to prevent the liquid running out. The luminous ring being formed as above-mentioned, the tube was put into the gallipot of boiling-hot water; in a short time the light began to descend from the top, and came waving down, in a pleasing manner, to the bottom of the tube in the hot water, and then was by degrees extinguished. The whole length of the tube, including the curvatures, was 26 inches. The most eligible solutions for this curious experiment, are those made with 640 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. Epsom salt, Glauber's salt, sea-salt, and sal ammonia: if either of the 2 former be used, the proper proportion is, 1 dr. of salt to each oz of water ; if either of the 2 latter, 1 5 gr. to each oz. of water will be sufficient. n. b. The experimentalist, before he views the descent of the light in the tube, should always remain in the dark for some little time, in order to get rid of all ex- traneous light adhering to the organs of vision, and to accommodate the eye to darkness. Section 10. The Effects of the Human Body, and of the Animal Fluids, on Spontaneous Light. The living Body. — Exper. 1 . On touching the luminous matter of fishes, the light adhered to the fingers and different parts of the hands; remained very lucid for some little time, and then gradually disappeared. But the same kind of matter being applied to pieces of wood, stone, and the like, of the same temperature as the laboratory, continued luminous on these substances for many hours. — Exper. 2. A piece of red blotting-paper, about 1 inch square, and 4 times doubled, was finely illuminated by matter from a herring, and applied to the upper part of the inside of the thigh. After the expiration of 1 5 or 20 minutea, it was taken off; when the light was quite extinguished. The experiment was repeated several times, and with the same effect. Another piece of the like paper was illuminated at the same time, and placed in the laboratory ; where it retained its light above 48 hours. — Exper. 3. A piece of shining wood was placed on the palm of the hand, and in- closed there for some time; on inspection, it was found to be more lucid than before. Many trials of this kind were made, with the like success. — Exper. 4. A dead glow-worm, being but slightly luminous, was breathed on several times; and its light increased both in magnitude and brightness. The experiment was fre- quently repeated, with the same result. minimal Fluids. — Blood. Exper. 5. A person having received a contusion, but otherwise in health, was bled. The next day some herring-light was mixed with about 2 oz. of the crassamentum or red coagulated part of the blood, by stirring them well together with a knife: it caused it to be slightly luminous, but the light was not of long duration. Nearly the same result followed the mixture of lucid matter with the recent crassamentum of persons labouring under inflammatory diseases, as the pleurisy and rheumatism. — Exper. 6. But when mixed with cras- samentum that had been kept for some time, and become black and somewhat offensive to the smell, the light seemed to be more quickly extinguished. — Exper. 7. A singular phenomenon happened several times, on mixing fish-light with pru- trescent bloody serum. It would not incorporate, but was ejected in globules, like quicksilver when rubbed with any unctuous substance, and afterwards adhered to the side of the vessel in which the mixture was made, in the form of a lucid ring. — Exper. 8. The luminous matter of a herring was mixed with about 2 oz. of pure serum, from the healthy subject of the 5th experiment: it soon became finely il- luminated, and retained its shining appearance for a long time, whenever it was TOL. XC.] PHILOSOPHICAL TRANSACTIONS. 641 stirred or agitated. — Exper. Q. The recent serum, drawn from patients afflicted with inflammatory complaints, was illuminated pretty much in the same manner as in the 8th experiment; and often retained light above 48 hours. Urine. — Exper. 10. Mackerel-light being mixed, by strong agitation, with some fresh urine from a healthy person, a glimpse of light was retained at first, and then was gradually extinguished. But stale and pungent urine, being incorporated with luminous matter, had a still greater extinguishing effect. Bile. — Exper. 1 1 . Some bile, taken from a person who died of a suppression of urine, had herring-light mixed with it, which soon became extinct. Another trial was made with a different bile, and with the same result. Milk. — Exper. 12. Human milk not being easily obtained, some mackerel-light was incorporated, by agitation, with 2 oz. of fresh cow's milk, which was thus rendered finely luminous, and continued shining above 24 hours. Fresh cream also retained some light; though it was not so visible as with milk, owing probably to its thickness. But, when either milk or cream turn sour, they contract a very extinguishing property. A quart of milk was kept 5 days, in a moderately cool place, in June ; by that time it was changed into a mixture somewhat resembling curds and whey, that is, into a soft smooth coagulated part, and a very thin one, both which were acidulous. Some fine mackerel-light was mixed with 2 oz. of each of them, in separate phials, and they extinguished it immediately. X. Experiments for Decomposing the Muriatic Acid. By Mr. Wm. Henry, p. 188. One of the first objects, in the analysis of a compound body, should be its complete separation from all other substances, which, by their presence, may tend to introduce uncertainty into the results of the processes that are employed. But it is seldom that a simplicity so desirable can be attained in the objects of chemical research; for, agreeably to a known law of affinity, the last portions of any sub- stance are separated with peculiar difficulty; the force of attraction appearing to increase, as we recede from the point of saturation. In a liquid state, the muriatic acid is a totally unfit subject for analytic experiment; for, in the strongest form under which it can be procured, it still contains a large proportion of water. This watery portion, besides the complexity which it introduces into the results of experiments, prevents any combustible substance that may be applied, from acting on the truly acid part; because that class of bodies, having less difficulty in at- tracting oxygen from the water than from the acid, will necessarily take it from the former source. The state of gas therefore is the only one in which the mu- riatic acid can become a proper object of analysis. In the series of experiments on this gas, which I am now about to describe, I employed the electric fluid, as an agent much preferable to artificial heat. This mode of operating enables us to confine accurately the gases submitted to experi- ment; the phenomena that occur during the process may be distinctly observed and the comparison of the products with the original gases may be instituted with VOL. XVIII. 4 N 642 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. great exactness. The action of the electric fluid itself, as a decomponent, is ex- tremely powerful; for it is capable of separating from each other, the constituent parts of water, of the nitric and sulphuric acids, of the volatile alkali, of nitrous gas, and of several other bodies, whose components are strongly united. I began therefore with examining attentively the effects of the electric fluid on the muriatic acid gas, without admixture*. § J . On the Effects of Electricity on Muriatic Acid Gas. When strong electrical shocks were passed through a portion of muriatic acid gas, confined in a glass tube over mercury, the following appearances took place. The bulk of the gas, after 20 or 30 shocks, was considerably diminished; and a white deposit appeared on the inner surface of the tube, which considerably obscured its transparency. In some instances, both the contraction and deposit were much more remarkable than in others. The gas which issued from muriate of soda, soon after the affusion of sulphuric acid, and while the charge was yet warm, ex- hibited these appearances in an eminent degree. Of this gas, 307 measures were reduced, by 20 shocks, to 227, or were contracted nearly \. Gas from the same materials, after they had continued working for some hours, was diminished, by similar treatment, only about a 12th. These effects therefore it seemed probable depended in some measure on the presence of moisture; and I accordingly found that muriatic acid gas, after more than a week's exposure to muriate of lime, brought into contact with it immediately after cooling from a state of fusion, was scarcely -diminished at all; and that the deposit, though it still occurred, was less copious in quantity. This deposit was not, like corrosive sublimate, soluble in water; but had every property of the less saturated salt, calomel. The mercury by which the muriatic acid was confined, was therefore evidently oxidated; and to the combination of a part of the gas with the oxide thus produced, the diminution of bulk was doubtless to be ascribed. But it was uncertain from whence this oxygen was derived. It might either result from the decomposition of the acid gas, or of the water chemically combined with it. The following experiments were therefore made, to determine this point. Exper. 1. Through 1457 measures of muriatic acid gas, 300 electrical shocks were passed. There remained, after the admission of water, 100 measures of permanent gas, or not quite 7 from each 100 of the original gas, which on trial, appeared to be purely hydrogenous. — Exper. 2. Of the gas, dried by muriate of lime, 176 measures received 120 shocks. The residue of hydrogenous gas amounted to 1 1 measures, or rather more than 6 per cent. These experiments, and other similar ones, made on comparative portions of * The gases submitted to the action of electricity, in the following experiments, were confined in straight glass tubes of various diameters, armed at the sealed end with a conductor of gold, or platina, but generally of the latter metal. The shocks were as strong as could be given without breaking the tubes, which, notwithstanding every precaution, were often shaitered by the force of the explosion. Each measure of gas is equal to the bulk occupied by 1 gr. of mercury. — Orig. VOL. XC.1 PHILOSOPHICAL TRANSACTIONS. 643 muriatic acid gas, in its recent state, and after exposure to muriate of lime, con- vinced me that it was impossible, by this method, wholly to deprive the muriatic gas of water. The recent gas however, when electrified in smaller quantity than in exper. I, gave a larger proportion of hydrogenous gas; which shows, that some portion of its moisture was removed by exposure to muriate of lime. In order, if possible, to procure the gas perfectly dry, another mode of preparing it was re- sorted to. Alum and common salt were first well calcined, separately, to expel their water of crystallization, and, being then mixed, were distilled together in an earthen retort. The gas proceeding from these materials was received over dry mercury ; but though only the last portion that came over was reserved for experi- ment, it still, after the usual electrization, afforded a product of hydrogenous gas. In the course of the preceding experiments, I observed that the diminution of the muriatic acid gas stopped always at a certain point, beyond which it could not be carried by continuing the shocks. Gas also, which had been thus treated, when transferred to another tube, and again electrified, did not exhibit any further deposit. It became interesting therefore to know, whether the production of hydrogenous gas had a similar limitation; because the decision of this question would go far towards ascertaining its source. If the evolved hydrogenous gas arose from the decomposition of the acid, it might be expected to be produced, as long as any acid remained undecomposed. But if water were the origin of this gas, it would cease to be evolved, when the whole of the water contained in the gas had been resolved into its constituent principles. Exper. 3 and 4. Into 2 separate tubes, I passed known quantities of muriatic acid gas. Through the one portion 200 discharges were taken ; and through the other 400. On comparing the quantities of hydrogenous gas produced, it proved to bear exactly the same proportion, in each tube, to the gas originally submitted to experiment. Hence it may be inferred, that the hydrogenous gas, evolved by electrifying the muriatic acid, has its origin, not from the acid, but from the water which is intimately attached to it. The agency of the electric fluid appears also, from the following experiments, to be exerted, not only in disuniting the elements of water, but in promoting the union of the evolved oxygen with muriatic acid. Exper. 5. A mixture of common air and muriatic acid gas, in the proportion of 143 of the former to ll6 of the latter, was rapidly diminished by electrical shocks; 30 of which reduced the whole to 111*. The remainder consisted of muriatic acid and azotic gases, with a small proportion of oxygenous gas. The deposit formed on the tube was of the same kind as before, but much more abundant. Exper. 6. The same appearances were occasioned, much more remarkably, by electrifying muriatic acid with oxygenous gas; and the contraction continued till the mercury rose so as to touch the extremity of the platina conductor. At each * This experiment suggests an additional reason, to that already given, for the greater diminution of the first, than of the subsequent portions of muriatic acid gas ; for the former may be presumed to have been much more adulterated than the latter, with the atmospherical air of the vessels. — Orig. 4 N2 044 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. explosion, a dense white cloud was seen in the tube, which soon settled on its inner surface, and was of exactly the same chemical composition as the one already described. Nitrous gas and muriatic gas, when electrified together, underwent a similar change. In order to ascertain whether the mercury by which the gases were confined, in the above experiments, had any influence on their results, they were repeated in an instrument made, purposely for the occasion, by Mr. Cuthbertson, of London. It consisted of a glass tube, ground at each end, with the view of receiving 2 stoppers, each perforated with platina wire, which projected into the cavity of the tube. When the stoppers were in their places, the extremities of the wires were at the distance of about half an inch ; and, by properly disposing the apparatus, electrical shocks might be passed through any gas or mixture of gases, with the contact only of glass and platina. Exper. 7. In this tube I electrified the muriatic acid gas, and then admitted to it an infusion of litmus. The sudden destruction of its colour evinced the for- mation of oxygenated muriatic acid. Not the smallest deposit appeared on the tube. Exper. 8 and 9. The same phenomenon took place, when an infusion of litmus was brought into contact with a mixture of common air and muriatic acid, and of oxygenous gas and muriatic acid, after electrization in this instrument; oxygenated muriatic acid being produced in both cases. The above facts prove, that the combination of oxygen with muriatic acid, in these experiments, is not occasioned by a pre-disposing affinity in the mercury to combine with oxygenated muriatic acid; but that the electric fluid serves actually as an intermedium, in combining the muriatic acid with oxygen. From the re- lation of these experiments it appears, that not the smallest progress had been made by them, towards the decomposition of the muriatic acid. I resolved there- fore to attempt its analysis, in a similar manner, with the aid of combustible gases. $ 2. Effects of electrifying the Muriatic Acid Gas with inflammable Substances. In a memoir read before the r. s., and inserted in their Trans, for 1797, I have shown, that when electrical shocks are passed repeatedly through a confined portion of carbonated hydrogenous gas, the water held in solution by the gas is decomposed by the carbon, which forms a constituent part of it; that carbonic acid is formed; and an addition made of hydrogenous gas. Hence the bulk of the carbonated hy- drogen gas is considerably enlarged by this process; which shows, by its results, that the affinity of carbon for oxygen is rendered much more powerful and efficient by the electric fluid. I have since found that other oxygenated substan- ces are decomposed, by electrifying them with carbonated hydrogen gas. Nitrous gas, for example, is speedily destroyed by this process, and carbonic acid and azotic gases are obtained. Every attempt to decompose the muriatic acid must be founded on the pre- VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 6l5 sumption that it is an oxygenated substance; as those bodies promise to be the most successful agents that possess a strong affinity for oxygen. Now, of all known bodies, charcoal most strongly attracts oxygen ; I have therefore repeatedly attempted the destruction of this acid, by passing it over red-hot charcoal. But in a series of experiments, which I made some time since, with this view, in con- junction with Mr. Rupp, we soon found reason to be dissatisfied with the difficulty and uncertainty of this process. An immense production of hydrogenous gas took place; but it was not easy to determine whether it had its origin from real acid, or from water. Our experiments however, though insufficient to furnish de- cisive proof, induced us to believe that it had the latter origin. It next occurred to me, that the comparative affinities of the muriatic radical, whatever it may be, and of charcoal, for oxygen, would be elegantly and satis- factorily ascertained, by electrifying together the carbonated hydrogen and muriatic gases. If the muriatic acid be capable of decomposition by carbon, it might be expected to be destroyed by this process ; and the exact quantity of acid decomposed, and the nature and quantity of the products would thus be easily determined. I electrified therefore, the muriatic acid and carbonated hydrogen gases, with the most scrupulous attention to the phenomena and results. That the electric fluid might not be misapplied, in decomposing the water of the carbonated hydrogen gas, it was kept more than a week, before use, over quick-lime, introduced to it while yet hot. Exper. 10. Of this carbonated hydrogenous gas, 186 measures were expanded, by 130 shocks, to 21 1 ; that is, the gas was increased about \ its bulk. Exper. 11. Of the same gas, 84 measures were mixed with 116 of muriatic acid gas, dried by muriate of lime. By 120 shocks, the mixture was a little dilated. After the admission of a drop or two of water, there remained Ql measures; i. e. the addition of permanent gas was 7 measures, or about as much as might have been expected from the muriatic gas alone. Exper. 12. Eighty-three measures of dry carbonated hydrogenous gas, with 89 of muriatic acid gas, received 200 shocks. The permanent residue, after the ad- mission of water, was 101 measures: the addition therefore amounted to 18. Of the added 18, 6 may be accounted for by the decomposition of the water of the muriatic gas, and 10 by that of the carbonated hydrogenous gas. There remain therefore only 2 measures that can be supposed to be produced from the muriatic acid gas; a quantity too small to afford grounds for supposing them to arise from decomposed acid. Exper. 13. Dry carbonated hydrogenous gas 132 measures, mixed with dry muriatic gas 108 making 240 by 200 shocks, expanded to 208. Part of this gas was then transferred to another tube, and the proportion of per- manent gas ascertained. Through the remainder, 150 additional shocks were 646 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. passed, before the amount of the gas thus evolved was determined. In both, it bore exactly the same proportion to the original gas ; which shows, that by con- tinuing the electrization, no further effects were produced. A great variety of similar experiments convinced me, that by electrifying to- gether the carbonated hydrogenous and muriatic gases, not the smallest progress was made towards the decomposition of the latter. All that was thus effected, consisted in the decomposition of the water of the 2 gases, by the carbon of the combustible gas; and when this was completely accomplished, no further effect ensued from continuing the electrization. The generation of carbonic acid was proved by the following experiment. Exper. 14. To a mixture of carbonated hydrogen and muriatic gases, after having received above 100 shocks, a drop of water was admitted, which absorbed the muriatic acid. The liquid was then taken up by blotting-paper; and the re- siduary gas, being transferred into another tube, was brought into contact with a solution of pure barytic earth. The precipitation of this solution evinced the presence of carbonic acid. It was desirable however that the effects should be ascertained, of electrifying together pure muriatic acid and pure carbonated hydrogenous gas, both perfectly free from water. Now, from the experiments related in § 1, it appears highly probable, that a complete purification from moisture is produced, in both gases, by the action of the electric fluid ; all the water they before contained being thus decomposed. In the following experiments therefore the 2 gases were separately electrified, before they were submitted to this process conjointly. Exper. 15. To a portion of muriatic acid, diminished by the action of electricity from 144 to 121 measures, 27 measures of carbonated hydrogenous gas, expanded as far as possible, were added, and 200 shocks passed through the mixture. The addition of permanent gas amounted to 14 measures; 10 of which may be traced to the muriatic acid, and were evolved by its separate electrization. The remaining 4 measures, which remain to be accounted for, are too small a quantity to be ascribed to the decomposition of the acid. Exper. l6. To a quantity of carbonated hydrogenous gas, which had received 400 shocks, and occupied the space of 212 measures, were added 232 of muriatic acid, through which 200 shocks had been previously passed. The electrization of the mixture was next continued, till 800 discharges had taken place. On examining the mixture of gases, during this operation, no change whatever took place; and after its close no more muriatic acid had disappeared, than would have been deficient after the first electrization; nor was there any further production of per- manent gas. Exper. L7« The same result was obtained, by electrifying together 280 measures of carbonated hydrogenous gas, previously expanded by 600 shocks, and 114 of muriatic acid, after 400 shocks. The additional discharge through this mixture, of 1 000 shocks, did not evince the smallest progress towards the decomposition of the muriatic acid. VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 647 Exper. 18. In the naturally moist state of these gases it follows, from the 14th experiment, that carbonic acid is produced by electrifying them in conjunction. It appeared of some importance to ascertain whether, after a previous decomposition of their moisture, carbonic acid would continue to be generated. But the electrified car- bonated hydrogenous gas itself contains carbonic acid, which, unless removed, would render the result of the experiment undecisive. This was accomplished by passing up, to a portion of electrified gas, a bubble or two of dry ammoniacal gas, which, uniting with the carbonic acid, would condense any portion of it that might be present. The remainder was transferred into another tube; and to this car- bonated hydrogenous gas, perfectly deprived both of moisture and carbonic acid, muriatic acid gas, previously electrified, was added, and electrical shocks were passed through the mixture. A drop of water was then admitted ; and the residuary gas, after having been dried, was transferred into another tube. On passing up barytic water, not the smallest trace of carbonic acid could be discovered. From the preceding experiments, the following conclusions may be deduced. 1 . The muriatic acid gas, in the driest state in which it can be procured, still contains a portion of water. From a calculation founded on the experiments described in § 1, the grounds of which are too obvious to require being stated, it follows, that 100 cubical inches of muriatic gas, after exposure to muriate of lime still hold in combination 1 .4 grain of water. 2. When electrical shocks are passed through this gas, the watery portion is decomposed. The hydrogen of the water, uniting with the electric matter, constitutes hydrogenous gas, and the oxygen unites with the muriatic acid; which last, acting on the mercury, composes muriate of mercury. 3. The electric fluid serves as an intermedium, in combining oxygen with muriatic acid. 4. The really acid portion of muriatic gas does not sustain any decomposition by the action of electricity. 5. When electric shocks are passed through a mixture of carbonated hydrogen and muriatic acid gases, the water held in solution by these gases is decomposed by the carbon of the compound inflammable gas; and carbonic acid and hydrogenous gases are the result. 6. When all the water of the two gases has been decomposed, no effect ensues from con- tinuing the electrization ; or, if the water of each gas has been previously destroyed, by electrifying them separately, no further effect ensues from electrifying them conjointly. 7- Since therefore carbon, though placed under the most favourable circumstances for abstracting from the muriatic acid, and combining with its oxygen, evinces no such tendency, it may be inferred, that if the muriatic acid be an oxygenated substance, its radical has a stronger affinity for oxygen than charcoal possesses. Though the first impressions excited in my mind by the total failure of the above experiments, in accomplishing one of the greatest objects of modern che- mistry, have induced me for some time to withhold them from the society, I am satisfied by reflection that this communication is not without expediency. The means employed in attempting the analysis of the muriatic acid, were such as, 648 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. after mature deliberation, appeared to me most to promise success; and the expe- riments were attended with a degree of labour, which can only be estimated by those who have been engaged in similar pursuits ; not one-third of those which were really made having been described, in the foregoing account of them. It may spare therefore to others a fruitless application of time and trouble, to be made acquainted with what I have done ; and the collateral facts, which have presented themselves in the inquiry, are perhaps not without curiosity or value. From the result of these experiments, I apprehend all hope must be relin- quished, of effecting the decomposition of the muriatic acid, in the way of single elective affinity. They furnish also a strong probability, that the basis of the muriatic acid is some unknown body; for, no combustible substance with which we are acquainted, can retain oxygen, when submitted, in contact with charcoal, to the action of electricity, or of a high temperature. The analysis of this acid must, in future, be attempted with the aid of complicated affinities. Thus, in the masterly experiment of Mr.Tennant, phosphorus, which attracts oxygen less strongly than charcoal, by the intermediation of lime decomposes the carbonic acid. Yet, led by the analogy of this fact, its discoverer found that a similar artifice did not suc- ceed in decomposing the muriatic acid. " As vital air," he observes, " is attracted by a compound of phosphorus and calcareous earth, more powerfully than by char- coal, I was desirous of trying their efficacy on those acids which may from analogy be supposed to contain vital air, but which are not affected by the application of charcoal. With this intention, I made phosphorus pass through a compound of marine acid and calcareous earth, and also of fluor acid and calcareous earth, but without producing in either of them any alteration. Since the strong attraction which these acids have for calcareous earth tends to prevent their decomposition, it might be thought, that in this manner they were not more disposed to part with vital air than by the attraction of charcoal : but this however does not appear to be the fact. I have found, that phosphorus cannot be obtained by passing marine acid through a compound of bones and charcoal when red-hot. The attraction therefore of phosphorus and lime for vital air, exceeds the attraction of charcoal, by a greater force than that arising from the attraction of marine acid for lime."* By means similar to those employed in attempting the analysis of the muriatic acid, I tried to effect that of the fluoric acid. When electrified alone, in a glass tube coated internally with wax, it sustained a diminution of bulk, and there remained a portion of hydrogenous gas. But neither in this mode, nor by sub- mitting it, mixed with carbonated hydrogenous gas, to the action of electricity, was any progress made towards its analysis. These experiments however render it probable, that the fluoric acid, like the muriatic, is susceptible of still further oxygenation, in which state it becomes capable of acting on mercury. The car- bonic acid, on the contrary, appears not to admit of different degrees of oxygena- tion. When the electric shock has been repeatedly passed through a portion of this * Phil. Trans., vol.81, p. 184.— Orig. VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 04g acid gas, its bulk is enlarged, and a permanent gas is produced, which is evidently a mixture of oxygenous and hydrogenous gases ; for when an electrical spark is passed through the gas that remains after the absorption of the carbonic acid by caustic alkali, it immediately explodes. These results even take place on electrify- ing carbonic acid from marble, previously calcined in a low red-heat, to expel its water, and then distilled in an earthen retort.* XI. On a New Fulminating Mercury. By Edw. Howard, Esq. F. R. S. p. 204. § 1. The mercurial preparations which fulminate, when mixed with sulphur, and gradually exposed to a gentle heat, are well known to chemists: they were discovered, and have been fully described, by Mr. Bayen.-f- MM. Brugnatelli and Van Mons have also produced fulminations by concussion, as well with nitrate of mercury and phosphorus, as with phosphorus and most other nitrates. J Cinnabar also is among the substances which, according to MM. Fourcroy and Vauquelin, detonate by concussion with oxymuriate of pot-ash. § Mr. Ameilon had, accord- ing to Mr. Berthollet, observed, that the precipitate obtained from nitrate of mer- cury by oxalic acid, fuses with a hissing noise || § 2. But mercury, and most if not all its oxides, may, by treatment with nitric acid and alcohol, be converted into a whitish crystallized powder, possessing all the inflammable properties of gunpowder, as well as many peculiar to itself. — I was led to this discovery, by a late assertion, that hydrogen is the basis of the muriatic acid : it induced me to attempt to combine different substances with hydrogen and oxygen. With this view, I mixed such substances with alcohol and nitric acid, as I thought, by pre-disposing affinity, favour as well as attract an aeid combination, of the hydrogen of the one, and the oxygen of the other. The pure red oxide of mercury appeared not unfit for this purpose; it was therefore intermixed with alcohol, and nitric acid was affused on both. The acid did not act on the alcohol, so immediately as when these fluids are alone mixed together, but first gradually dissolved the oxide: however, after some minutes had elapsed, a smell of ether was perceptible, and a white dense smoke, much resembling that from the liquor fumans of Libavius, was emitted with ebullition. The mixture then threw down a dark-ooloured precipitate, which by degrees became nearly white. This precipi- tate I separated by filtration; and observing it to be crystallized in small acicular crystals, of a saline taste, and also finding a part of the mercury volatilized in the white fumes, I must acknowledge I was not altogether without hopes that muriatic * Messrs. Landriani and Van Marum (Annates de Chimie, torn. 2, p. 270), obtained only hydroge- nous gas, by electrifying the carbonic acid gas. But the conductor of their apparatus was an iron one ; which metal would combine with the oxygen of the water, and prevent it from appearing in a gaseous state. In my experiments, the conductors were of platina. — Orig. + Opuscules Chimique de Bayen, torn. 1, p. 346", and note in p. 344. % Annales de Chimie, torn. 27, p. 74 and 79. § Ibid. torn. 21, p. 238. || This fact has been misrepresented, in the introduction to a work entitled The chemical Principles of the metallic Arts, by W. Richardson, sur- geon, f a.s., Sc. (p. 57). — Orig. VOL. XVIII. 4 O 650 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. acid had been formed, and united to the mercurial oxide. I therefore, for obvious reasons, poured sulphuric acid on the dried crystalline mass, when a violent effer- vescence ensued, and, to my great astonishment, an explosion took place. The singularity of this explosion induced me to repeat the process several times ; and finding that I always obtained the same kind of powder, I prepared a quantity of it, and was led to make the following series of experiments. § 3. I first attempted to make the mercurial powder fulminate by concussion; and for that purpose laid about 1 gr. of it on a cold anvil, and struck it with a hammer, likewise cold : it detonated slightly, not being, as I suppose, struck with a flat blow ; for, on using 3 or 4 gr., a very stunning disagreeable noise was pro- duced, and the faces both of the hammer and the anvil were much indented. Half a grain or 1 gr., if quite dry, is as much as ought to be used on such an occasion. The shock of an electrical battery, sent through 5 or 6 gr. of the pow- der, produces a very similar effect: it seems indeed that a strong electrical shock generally acts on fulminating substances like the blow of a hammer. Messrs. Fourcroy and Vauquelin found this to be the case with all their mixtures of oxy- muriate of pot-ash.* To ascertain at what temperature the mercurial powder explodes, 2 or 3 gr. of it were floated on oil, in a capsule of leaf tin ; the bulb of a Fahrenheit's thermo- meter was made just to touch the surface of the oil, which was then gradually heated till the powder exploded, as the mercury of the thermometer reached the 368th degree. § 4. Desirous of comparing the strength of the mercurial compound with that of gunpowder, I made the following experiment, in the presence of my friend Mr. Abernethy. Finding that the powder could be fired by flint and steel, with- out a disagreeable noise, a common gunpowder proof, capable of containing 1 1 gr. of fine gunpowder, was filled with it, and fired in the usual way: the report was sharp, but not loud. The person who held the instrument in his hand felt no recoil ; but the explosion laid open the upper part of the barrel, nearly from the touch-hole to the muzzle, and struck off the hand of the register, the surface of which was evenly indented, to the depth of 0.1 of an inch, as if it had received the impression of a punch. — The instrument used in this experiment being famili- arly known, it is therefore scarcely necessary to describe it; suffice it to say, that it was of brass, mounted with a spring register, the moveable hand of which closed up the muzzle to receive and graduate the violence of the explosion. The barrel was £ an inch in caliber, and nearly -; an inch thick, except where a spring of the lock impaired -^ its thickness. $ 5. A gun belonging to Mr. Keir, an ingenious artist of Camden-town, was next charged with 1 7 gr. of the mercurial powder, and a leaden bullet. A block of wood was placed at about 8 yards from the muzzle, to receive the ball, and the gun was fired by a fuse. No recoil seemed to have taken place ; as the barrel was * Annale de Chimie, torn. 21, p. 239. — Orig. VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 65] not moved from its position, though it was in no ways confined. The report was feeble : the bullet, Mr. Keir conceived, from the impression made on the wood, had been projected with about half the force it would have been by an ordinary charge, or 68 gr., of the best gunpowder. We therefore re-charged the gun with 34 gr. of the mercurial powder ; and, as the great strength of the piece removed any apprehension of danger, Mr. Keir fired it from his shoulder, aiming at the same block of wood. The report was like the first in § 4, sharp, but not louder than might have been expected from a charge of gunpowder. Fortunately, Mr. Keir was not hurt, but the gun was burst in an extraordinary manner. The breech was what is called a patent one, of the best forged iron, consisting of a chamber 0.4 of an inch thick all round, and 0.4 of an inch in caliber ; it was torn open and flawed in many directions, and the gold touch-hole driven out. The barrel, into which the breech was screwed, was 0.5 of an inch thick ; it was split by a single crack 3 inches long ; but this did not appear to me to be the imme- diate effect of the explosion, I think the screw of the breech, being suddenly en- larged, acted as a wedge on the barrel. The ball missed the block of wood, and struck against a wall, which had already been the receptacle of so many bullets, that we could not satisfy ourselves about the impression made by this last. § 6. As it was pretty plain that no gun could confine a quantity of the mercu- rial powder sufficient to project a bullet, with a greater force than an ordinary charge of gunpowder, I determined to try its comparative strength in another way. I procured 1 blocks of wood, very nearly of the same size and strength, and bored them with the same instrument to the same depth. The one was charged with 4/ oz. of the best Dartford gunpowder, and the other with 4. oz. of the mer- curial powder ; both were alike buried in sand, and fired by a train communicating with the powders by a small touch-hole. The block containing the gunpowder was simply split into 3 pieces : that charged with the mercurial powder was burst in every direction, and the parts immediately contiguous to the powder were abso- lutely pounded, yet the whole hung together, whereas the block split by the gun- powder had its parts fairly separated. The sand surrounding the gunpowder was undoubtedly most disturbed: in short, the mercurial powder appeared to have acted with the greatest energy, but only within certain limits. § 7. The effects of the mercurial powder, in the last experiments, made me believe that it might be confined, during its explosion, in the centre of a hollow glass globe. Having therefore provided such a vessel, 7 inches in diameter, and nearly half an inch thick, mounted with brass caps, and a stop cock, (see pi. 11, fig. l), I placed 10 gr. of the mercurial powder on very thin paper, laid an iron wire 149th of an inch thick across the paper, through the midst of the powder, and, closing the paper, tied it fast at both extremities, with silk, to the wire. As the inclosed powder was now attached to the middle of the wire, each end of which was connected with the brass caps, the packet of powder became, by this disposition, fixed in the centre of the globe. Such a charge of an electrical bat- 4 o 2 652 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. tery was then sent along the wire, as a preliminary experiment had shown me would, by making the wire red-hot, inflame the powder. The glass globe with- stood the explosion, and of course retained whatever gases were generated ; its interior was thinly coated with quicksilver in a very divided state. A bent glass tube was now screwed to the stop-cock of the brass cap, which being introduced under a glass jar standing in the mercurial bath, the stop-cock was opened. Three cubical inches of air rushed out, and a 4th was set at liberty when the apparatus was removed to the water-tub. The explosion being repeated, and the air all received over water, the quantity did not vary. To avoid an error from change of temperature, the glass globe was, both before and after the explosion, immersed in water of the samel temperature. It appears therefore, that the JOgr. of powder, produced 4 cubical inches only of air. To continue the comparison between the mercurial powder and gunpowder, 10 gr. of the best Dartford gunpowder were in a similar manner set fire to in the glass globe : it remained entire. The whole of the powder did not explode, for some complete grains were to be observed adhering to the interior surface of the glass. Little need be said of the nature of the gases generated during the com- bustion of gunpowder : they must have been, carbonic acid gas, nitrogen gas, sulphureous acid gas, and, according to Lavoisier,* perhaps hydrogen gas. As to the quantity of these gases, it is obvious that it could not be ascertained ; because the 2 first were, at least in part, speedily absorbed by the alkali of the nitre, left pure after the decomposition of its nitric acid. ^ 8. From the experiments related in the 4th and 5th §, in which the gun- powder proof and the gun were burst, it might be inferred, that the astonishing force of the mercurial powder is to be attributed to the rapidity of its combustion ; and, a train of several inches in length being consumed in a single flash, it is evident that its combustion must be rapid. From the experiments of the 6th and 7th §, it is sufficiently plain that this force is restrained to a narrow limit; both because the block of wood charged with the mercurial powder was more shattered than that charged with the gunpowder, while the sand surrounding it was least disturbed; and also because the glass globe withstood the explosion of lOgr. of the powder fixed in its centre : a charge I have twice found sufficient to destroy old pistol barrels, which were not injured by being fired when full of the best gun- powder. It also appears, from the last experiment, that lOgr. of the powder, produced by ignition 4 cubical inches only of air ; and it is not to be supposed that the generation, however rapid, of 4 cubical inches of air, will alone account for the described force ; neither can it be accounted for by the formation of a little water, which, as will hereafter be shown, happens at the same moment : the quan- tity formed from 10 gr. must be so trifling, that I cannot ascribe much force to the expansion of its vapour. The sudden vaporization of a part of the mercury, seems to me a principal cause of this immense, yet limited force ; because its limi- * See Lavoisier, Traitc elementaire, p. 527. — Orig. VOL. XC.l PHILOSOPHICAL TRANSACTIONS. 653 tation may then be explained, as it is well known that mercury easily parts with caloric, and requires a temperature of 600 degrees of Fahrenheit, to be main- tained in the vaporous state. That the mercury is really converted into vapour, by ignition of the powder, may be inferred from the thin coat of divided quick- silver, which, after the explosion in the glass globe, covered its interior surface; and also from the quicksilver with which a tallow candle, or a piece of gold, may be evenly coated, by being held at a small distance from the inflamed powder. These facts certainly render it more than probable, though they do not demon- strate, that the mercury is volatilized ; because it is not unlikely that many mer- curial particles are mechanically impelled against the surface of the glass, the gold, and the tallow. As to the force of dilated mercury, Mr. Baume relates a remarkable instance of it, as follows. " Un alchymiste se presenta a Mr. GeoiTroy, et l'assura qu'il avoit trouve le moyen de fixer le mercure par une operation fort simple. II fit con- struire six boltes rondes en fer fort epais, qui entroient les imes dans les autres ; la derniere etoit assujettie par deux cercles de fer qui se croisoient en angles droits. On avoit mis quelques livres de mercure dans la capacite de la premiere : on mit cet appareil dans un fourneau assez rempli de charbon pour faire rougir a blanc les boites de fer; mais, lorsque la chaleur eut penetre suffisamment le mercure, les boites creverent, avec une telle explosion qu'il se fit un bruit epouvantable : des morceaux de boites furent lances avec tant de rapidite, qu'il y en eut qui passerent au travers de deux planchers ; d'autres firent sur la muraille des effets semblables a ceux des eclats de bombes."* Had the alchemist proposed to fix water by the same apparatus, the nest of boxes must, I suppose, have likewise been ruptured; yet it does not follow that the explosion would have been so tremendous ; indeed it is probable that it would not, for if, as Mr. Kirwan remarked to me, substances which have the greatest specific gravity, have likewise the greatest attraction of cohesion, the supposition that the vapour of mercury exceeds in expansive force the vapour of water, would agree with a position of Sir Isaac Newton, that those particles recede from each other with the greatest force, and are most difficultly brought together, which on contact cohere most strongly. -J- § g. Before attempting to investigate the constituent principles of this powder, it will be proper to describe the process and manipulations which, from frequent trials, seem to me best calculated to produce it. 100 gr., or a greater proportional quantity, of quicksilver, not exceeding 500 gr.,^ are to be dissolved, with heat, in a measured ounce and a half of nitric acid. § This solution being poured cold on 2 measured oz. of alcohol, 1 1 previously introduced into any convenient glass vessel, a moderate heat is to be applied till an effervescence is excited. A white fume then * Chymie experimentale et raisonnee, torn. 2, p. 393. Paris, 8°, 1773. f Newton's Optics, p. 372, 4th ed. Lond. 1730. % The reason of this limitation is not on account of any danger attending the process ; but because the quantities of nitric acid and alcohol required for more than 500 gr., would ;excite a degree of heat detrimental to the preparation. § Of the specific gravity of about 1.3. || Of the specific gravity of about .849. — Orig. 654 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. begins to undulate on the surface of the liquor ; and the powder will be gradually precipitated, on the cessation of action and re-action. The precipitation is to be immediately collected on a filter, well washed with distilled water, and carefully dried in a heat not much exceeding that of a water bath. The immediate edulco- ration of the powder is material, because it is liable to the re-action of the nitric acid ; and while any of that acid adheres to it, it is very subject to the influence of light. Let it also be cautiously remembered, that the mercurial solution is to be poured on the alcohol. I have recommended quicksilver to be used in preference to an oxide, because it seems to answer equally, and is less expensive ; otherwise, not only the pure red oxide, bui the red nitrous oxide and turpeth may be substituted ; neither does it seem essential to attend to the precise specific gravity of the acid, or the alcohol. The rectified spirit of wine and the nitrous acid of commerce, never failed to pro- duce a fulminating mercury. It is indeed true, that the powder prepared without attention, is produced in different quantities, varies in colour, and probably in strength. From analogy, I am disposed to think the whitest is the strongest; for it is well known, that black precipitates of mercury approach the nearest to the metallic state. The variation in quantity is remarkable ; the smallest quantity I ever obtained from 100 gr. of quicksilver being 120 gr, and the largest 132 gr. Much depends on very minute circumstances. The greatest product seems to be obtained, when a vessel is used which condenses and causes most ether to return into the mother liquor ; besides which, care is to be had in applying the requisite heat, that a speedy, and not a violent action be effected. 1 00 gr. of an oxide are not so productive as 100 gr. of quicksilver. As to the colour, it seems to incline to black, when the action of the acid on the alcohol is most violent, and vice versi. § 10. I need not observe, that the gases which were generated during the com- bustion of the powder in the glass globe, were necessarily mixed with atmospheric air; the facility with which the electric fluid passes through a vacuum, made such a mixture unavoidable. The cubical inch of gas received over water was not readily absorbed by it : and as it soon extinguished a taper, without becoming red, or being itself inflamed, barytes let up to the 3 cubical inches received over mer- cury, when a carbonate of barytes was immediately precipitated. The residue of several explosions, after the carbonic acid had been separated, was found, by the test of nitrous gas, to contain nitrogen or azotic gas; which does not proceed from any decomposition of atmospheric air, because the powder may be made to explode under the exhausted receiver of an air-pump. It is therefore manifest that the gases, generated during the combustion of the fulminating mercury, consist of carbonic acid and nitrogen gases. $11. The principal re-agents which decompose the mercurial powder, are the nitric, the sulphuric, and the muriatic acids. The nitric changes the whole into nitrous gas, carbonic acid gas, acetous acid, and nitrate of mercury. I resolved it into these different principles, by distilling it pneumatically with nitric acid : VOL. XC.J PHILOSOPHICAL TRANSACTIONS. 655 this acid, on the application of heat, soon dissolved the powder, and extricated a quantity of gas, which was found, by well known tests, to be nitrous gas mixed with carbonic acid gas. The distillation was carried on till gas no longer came over. The liquor of the retort was then mixed with the liquor collected in the receiver, and the whole saturated with pot-ash ; which precipitated the mercury in a yellowish-brown powder, nearly as it would have done from a solution of nitrate of mercury. This precipitate was separated by a filter, and the filtrated liquor evaporated to a dry salt, which was washed with alcohol. A portion of the salt being refused by this menstruum, it was separated by filtration, and recognized by all its properties, to be nitrate of pot-ash. The alcoholic liquor was likewise eva- porated to a dry salt, which, on the affusion of a little concentrate sulphuric acid, emitted acetous acid, contaminated with a feeble smell of nitrous acid, owing to the solubility of a small portion of the nitre in the alcohol. § 12. The sulphuric acid acts on the powder in a remarkable manner, as already has been noticed. A very concentrate acid produces an explosion nearly at the instant of contact, on account, I presume, of the sudden and copious disengage- ment of caloric from a portion of the powder which is decomposed by the acid. An acid somewhat less concentrate likewise extricates a considerable quantity of caloric, with a good deal of gas ; but, as it effects a complete decomposition, it causes no explosion. An acid diluted with an equal quantity of water, by the aid of a little heat, separates the gas so much less rapidly, that it may with safety be collected in a pneumatic apparatus. But, whatever be the density of the acid, provided no explosion be produced, there remains in the sulphuric liquor, after the separation of the gas, a white uninflammable and uncrystallized powder, mixed with some minute globules of quicksilver. To estimate the quantity, and observe the nature, of this uninflammable sub- stance, I treated 100 gr. of the fulminating mercury with sulphuric acid a little diluted. The gas being separated, I decanted off the liquor as it became clear, and freed the insoluble powder from acid, by edulcoration with distilled water; after which I dried it, and found it weighed only 84 gr.; consequently had lost 16 gr. of its original weight. Suspecting, from the operation of the nitric acid in the former experiment, that these 84 gr., with the exception of the quicksilver globules, were oxalate of mercury, I digested them in nitrate of lime, and found my suspicion just. The mercury of the oxalate united to the nitric acid, and the oxalic acid to the lime. A new insoluble compound was formed; it weighed, when washed and dry, 48.5 gr. Carbonate of pot-ash, separated the lime, and formed oxalate of pot-ash, capable of precipitating lime-water, and muriate of lime; though it had been depurated from excess of alkali, and from carbonic acid, by a previous addition of acetous acid. That the mercury of the oxalate in the 84 gr., had united to the nitric acid of the nitrate of lime, was proved by dropping muriatic acid into the liquor from which the substance demonstrated to be oxalate of lime had been separated; for a copious precipitation of calomel instantly ensued. 656 PHILOSOPHICAL TRANSACTIONS. [ANNO 1600. The sulphuric liquor, decanted from the oxalate of mercury, was now added to that with which it was edulcorated, and the whole saturated with carbonate of pot-ash. As effervescence ceased, a cloudiness and precipitation followed; and the precipitate, being collected, washed, and dried, weighed 3.4 gr.: it appeared to be a carbonate of mercury. On evaporating a portion of the saturated sulphuric liquor, I found nothing but sulphate of pot-ash ; nor had it any metallic taste. There then remains, without allowing for the weight of the carbonic acid united to the 3.4 gr., a deficit from the JOOgr. of mercurial powder, of 12.6gr., which I ascribe to the gas separated by the action of the sulphuric acid. To ascertain the quantity, and examine the nature, of the gas so separated, I introduced into a very small tubulated retort, 50 gr. of the mercurial powder, and poured on it 3 dr., by measure, of sulphuric acid, diluted with an equal quantity of water, and extricated the gas with the assistance of a gentle heat. I first received it over quicksilver, the surface of which, during the operation, partially covered itself with a little black powder.* The gas, by different trials, amounted from 28 to 31 cubical inches; it at first appeared to be nothing but carbonic acid, as it precipitated barytes water, and extinguished a taper, without being itself inflamed, or becoming red. But, on letting up to it liquid caustic ammonia, there was a residue of from 5 to 7 inches of a peculiar inflammable gas, which burnt with a greenish-blue flame. When I made use of the water-tub, I obtained, from the same materials, from 25 to 27 inches only of gas, though the average quantity of the peculiar inflammable gas was likewise from 5 to 7 inches; therefore the difference of the aggregate pro- duct, over the 2 fluids, must have arisen from the absorption, by the water, of a part of the carbonic acid in its nascent state. The variation of the quantity of the inflammable gas, when powder from the same parcel is used, seems to depend on the acid being a little more or less dilute. With respect to the nature of the peculiar inflammable gas, it is plain to me, from the reasons I shall immediately adduce, that it is no other than the gas, in a pure state, into which the nitrous etherized gas can be resolved, by treatment with dilute sulphuric acid. The Dutch chemists have shown,*}- that the nitrous etherized gas can be re- solved into nitrous gas, by exposure to concentrate sulphuric acid, and that, by using a dilute, instead of a concentrate acid, a gas is obtained which enlarges the flame of a burning taper, so much like the gaseous oxide of azote, that they mistook it for that substance, till they discovered that it was permanent over water, refused to detonate with hydrogen, and that the fallacious appearance was owing to a mixture of nitrous gas with an inflammable gas. The inflammable gas separated from the powder answers to the description of the gas which at first deceived the Dutch chemists; 1st, in being permanent over water; 2dly, refusing to detonate with hydrogen; and, 3dly, having the appearance of the gaseous • I cannot account for this appearance. f Journal de Physique, p. 250, Oct. 1794» — Orig. VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 657 oxide of azote, when mixed with nitrous gas. The gas separable by the same acid, from nitrous etherized gas, and from the mercurial powder, have therefore the same properties. Every chemist would thence conclude, that the nitrous etherized gas is a constituent part of the powder, had the inflammable and nitrous gas, instead of the inflammable and carbonic acid gas, been the mixed product extricated from it by dilute sulphuric acid. It however appears to me, that nitrous gas was really produced by the action of the dilute sulphuric acid ; and that, when produced, it united to an excess of oxygen present in the oxalate of mercury. To explain how this change might happen, I must premise that my experiments have shown me, that oxalate of mercury can exist in 2, if not in 3 states. 1st. By the discovery of Mr. Ameilon already quoted, the precipitate obtained by oxalic acid, from nitrate of mercury, fuses with a hissing noise. This precipitate is an oxalate of mercury, seemingly with excess of oxygen. Mercury dissolved in sulphuric acid and precipitated by oxalic acid, and also the pure red oxide of mercury digested with oxalic acid, give oxalates in the same state. 2dly. Acetate of mercury precipitated by oxalic acid, though a true oxalate is formed, has no kind of inflammability. I consider it as an oxalate with less oxygen than those above-mentioned. 3dly. A solution of nitrate of mercury boiled with dulcified spirit of nitre, gives an oxalate more inflammable than any other : perhaps it contains most oxygen. The oxalate of mercury remaining from the powder in the sulphuric liquor, is not only always in the same state as that precipitated from acetate of mercury, entirely devoid of inflammability, but contains globules of quicksilver ; consequently it must have parted with even more than its excess of oxygen ; and if nitrous gas was pre- sent, it would of course seize at least a portion of that oxygen. It is true, that globules of quicksilver may seem incompatible with nitrous acid ; but the quantity of the one may not correspond with that of the other, or the dilution of the acid may destroy its action. As to the presence of the carbonic acid, it must have arisen either from a complete* decomposition of a part of the oxalate; or, admitting the nitrous etherized gas to be a constituent principle of the powder, from a portion of the oxygen, not taken up by the nitrous gas, being united with the carbon of the etherized gas. § 13. The muriatic acid digested with the mercurial powder, dissolves a portion of it, without extricating any notable quantity of gas. The dissolution evaporated to a dry salt, tastes like corrosive sublimate ; and the portion which the acid does not take up, is left in the state of an uninflammable oxalate. § 14. These effects all tend to establish the existence of the nitrous etherized gas, as a^nstituent part of the powder ; and also corroborate the explanation I have ventured to give, of the action of the sulphuric acid. A measured l-±- oz. of nitrous acid, holding 100 gr. of mercury in solution, and 2 measured ounces of * Inflammable oxalate of mercury, made to fuse in a retort connected with the quicksilver tube, gives out carbonic acid gas. — Orig. VOL. XVIII. 4 P 658 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. alcohol, yield 00 cubical inches only of gas : whereas, without the intervention of mercury, they yield 210 inches. On the whole, I trust it will be thought reason- able to conclude, that the mercurial powder is composed of the nitrous etherized gas, and of oxalate of mercury with excess of oxygen. 1st. Because the nitric acid converts the mercurial powder entirely into nitrous gas, carbonic acid gas, acetous acid and nitrate of mercury. 2dly. Because the dilute sulphuric acid resolves it into an uninflammable oxalate of mercury, and separates from it a gas resembling that into which the same acid resolves the nitrous etherized gas. 3dly. Because an un- inflammable oxalate is also left, after the muriatic acid has converted a part of it into sublimate. 4thly. Because it cannot be formed by boiling nitrate of mercury in dulcified spirit of nitre ; though a very inflammable oxalate is by this means pro- duced. 5thly. Because the difference of the product of gas, from the same mea- sures of alcohol and nitrous acid, with and without mercury in solution, is not trifling ; and, 6thly. Because nitrogen gas was generated during its combustion in the glass globe. Should my conclusions be thought warranted by the reasons I have adduced, the theory of the combustion of the mercurial powder will be obvious to every chemist. The hydrogen of the oxalic acid, and of the etherized gas, is first united to the oxygen of the oxalate, forming water ;* the carbon is saturated with oxygen, form- ing carbonic acid gas ; and a part, if not the whole of the nitrogen of the etherized gas, is separated in the state of nitrogen gas ; both which last gases, it may be re- collected, were after the explosion present in the glass globe. The mercury is re- vived, and I presume thrown into vapour ; as may well be imagined, from the im- mense quantity of caloric extricated, by adding concentrate sulphuric acid to the mercurial powder. I will not venture to state with accuracy, in what proportions its constituent principles are combined. The affinities I have brought into play are complicated, and the constitution of the substances I have to deal with not fully known. But, to make round numbers, I will resume the statement, that 100 gr. of the mercurial powder lost 16 gr. of its original weight, by treatment with dilute sulphuric acid : 84 gr. of mercurial oxalate, mixed with a few minute globules of quicksilver, remained undissolved in the acid. The sulphuric liquor was saturated with carbonate of potash, and yielded 3.4 gr. of carbonate of mercury. If 1.4 gr. should be thought a proper allowance for the weight of carbonic acid in the 3.4 gr. I will make that deduction, and add the remaining 2 gr. to the 84 gr. of mercurial oxalate and quicksilver ; I shall then have, of oxalate and mercury 86 gr. and a deficit, to be ascribed to the nitrous etherized gas and excess of oxygen 14 100 It may perhaps be proper to proceed still further, and recur to the 48.5 gr. sepa- rated by nitrate of lime from the 84 gr. of mercurial oxalate and globules of quick- * Drops of water were observed on the internal surface of the globe, the day after several explosions had been produced in its centre.— Orig. VOL XC.] PHILOSOPHICAL TRANSACTIONS. 650, silver, in § 11th. These 48.5 gr. were proved to be chiefly oxalate of lime ; but they contained also a minute inseparable quantity of mercury, almost in the state of quicksilver, formerly part of the 84 gr. from which they were separated. Had the 48.5 gr. been pure calcareous oxalate, the quantity of pure oxalic acid in them would, according to Bergmann,* be 23.28 gr. Hence, by omitting the 2 gr. of mercury in the 3.4 gr. of carbonate, 100 gr. of the mercurial powder might have been said to contain, of pure oxalic acid 23.28 gr. ; of mercury 62.72 gr. ; and of nitrous etherized gas and excess of oxygen 14 gr. But, as the 48.5 gr. were not pure oxalate, inasmuch as they contained the mercury they received from the 84 gr. from which they were generated by the nitrate of lime, some allowance must be made for the mercury successively intermixed with the 84 gr. and the 48.5 gr. In order to make corresponding numbers, and allow for unavoidable errors, I shall estimate the quantity of that mercury to have amounted to 2 gr. which I must of course deduct from the 23.28 gr. of oxalic acid. I shall then have the following statement : That 100 gr. of the fulminating mercury ought to contain, of pure oxalic acid 21.28 gr. Of mercury formerly united to the oxalic acid 6*0.72 Of mercury dissolved in the sulphuric liquor 2 And of mercury left in the sulphuric liquor after the separation of the gases 2 Total of mercury 6*4.72 Of nitrous etherized gas and excess of oxygen 14. 100. Since 100 gr. of the powder seem to contain 64.72 gr. of mercury, it will be im- mediately inquired, what becomes of 100 gr. of quicksilver, when treated as directed, in the description of the process for preparing the fulminating mercury. It has been stated, in § 9, that 100 gr. of quicksilver produce, under different circum- stances, from 120 to 132 gr. of mercurial powder; and, if 100 gr. of this powder contain 64.72 gr. 120 gr. or 132 gr. must, by parity of reasoning, contain 78.06 gr. or 85.47 gr. ; therefore 13.34 gr. or 20.75 gr. more of the 100 gr. are immedi- ately accounted for; because 64.72 gr. -J- 13.34 gr. = 78.06, and 64.72 gr. + 20.75 gr. = 85.47 gr. The remaining deficiency of 21. 94 gr. or 14.53 gr. which with the 78.06 gr. or 85.47 gr. would complete the original 100 gr. of quicksilver, remains partly in the liquor from which the powder is separated, and is partly volatilized in the white dense fumes, which in the beginning of this paper I com- pared to the liquor fumans of Libavius. The mercury cannot, in either instance, be obtained in a form immediately indicative of its quantity ; and a series of experi- ments to ascertain the quantities in which many different substances can combine with mercury, is not my present object. After observing, that the mercury left in the residuary liquor can be precipitated in a very subtle dark powder, by carbonate of potash, I shall content myself with examining the nature of the white fumes. * Bergmann, de Acido Sacchari. Opuscula. torn. 1, $ 6. p. 248. Leipzig, 1788. — Orig. 4P 2 660 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. §15. It is clear that these white fumes contain mercury : they may be wholly condensed in a range of Woulfe's apparatus, charged with a solution of muriate of ammonia. When the operation is over, a white powder is seen floating with ether on the saline liquor, which, if the bottles are agitated, is entirely dissolved. After the mixture has been boiled, or for some time exposed to the atmosphere, it yields to caustic ammonia a precipitate, in all respects similar to that which is separated by caustic ammonia from corrosive sublimate. — I would infer from these facts, that the white dense fumes consist of mercury, or perhaps oxide of mercury, united to the nitrous etherized gas ; and that when the muriate of ammonia containing them is exposed to the atmosphere, or is boiled, the gas separates from the mercury ; and the excess of nitrous acid, which always comes over with nitrous ether, decomposes the ammoniacal muriate, and forms corrosive mercurial muriate or sublimate. This theory is corroborated, by comparing the quantity of gas estimated to be contained in the fulminating mercury, with the quantities of gas yielded from alcohol and nitrous acid, with and without mercury in solution ; not to mention that more ether, as well as more gas, is produced without the intervention of mercury ; and that, according to the Dutch chemists, the product of ether is always in the inverse ratio to the product of nitrous etherized gas. Should a further proof be thought necessary, of the existence of the nitrous etherized gas in the fulminating mercury, as well as in the white dense fumes, it may be added, that if a mixture of alcohol and nitrous acid holding mercury in solution, be so dilute, and exposed to a tempe- rature so low, that neither ether nor nitrous etherized gas are produced, the fulmi- nating mercury, or the white fumes, will never be generated : for, under such cir- cumstances, the mercury is precipitated chiefly in the state of an inflammable oxalate. Further, when we consider the different substances formed by an union of nitrous acid and alcohol, we are so far acquainted with all, except the ether and the nitrous etherized gas, as to create a presumption, that no others are capable of volatilizing mercury, at the very low temperature in which the white fumes exist, since during some minutes they are permanent over water of 40° Fahrenheit. § l6. Hitherto, as much only has been said of the gas which is separated from the mercurial powder by dilute sulphuric acid, as was necessary to identify it with that into which the same acid can resolve the nitrous etherized gas ; 1 have further to speak of its peculiarity.* The characteristic properties of the inflammable gas, seem to me to be the following: 1st. It does not diminish in volume, either with oxygen or nitrous gas. 2dly. It will not explode with oxygen by the electric shock, in a close vessel. 3dly. It burns like hydrocarbonate, but with a bluish green flame. And, 4thly. It is permanent over water. (§ 12.) It is of course either not formed, or is convertible into nitrous gas, by the concentrate nitric and muriatic acids ; be- cause, by those acids, no inflammable gas was extricated from the powder. * It must be first noticed, that it is never pure when obtained from the nitrous etherized gas j nor am I aware how it is to be purified, unless the nitrous gas could be taken from it, without being con- verted into nitrous acid ; for, by that acid, it would probably be itself converted into nitrous gas. — Orig. VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 66l Should this inflammable gas prove not to be a hydrocarbonate, I shall be disposed to conclude, that it has nitrogen for its basis : indeed, I am at this moment inclined to that opinion, because I find that Dr. Priestley, during his experiments on his de- phlogisticated nitrous air, once produced a gas which seems to have resembled this inflammable gas, both in the mode of burning, and in the colour of the flame. After the termination of the common solution of iron in spirit of nitre, he used heat, and got, he says,* " such a kind of air as I had brought nitrous air to be, by exposing it to iron, or liver of sulphur ; for, on the first trial, a candle burned in it with a much enlarged flame. At another time, the application of a candle to air produced in this manner, was attended with a real though not a loud explosion ; and, immediately after this, a greenish coloured flame descended from the top to the bottom of the vessel in which the air was contained. In the next produce of air, from the same process, the flame descended blue and very rapid, from the top to the bottom of the vessel." These greenish and blue coloured flames, descending from the top to the bottom of the vessel, are precisely descriptive of the inflammable gas separated from the powder. If it can be produced with certainty by the repetition of Dr. Priestley's experiments, or should it by any means be got pure from the nitrous etherized gas, my curiosity will excite me to make it the object of future research ; otherwise, I must confess, I shall feel more disposed to prosecute other chemical subjects : for, having reason to think that the density of the acid made a variation in the product of this gas, and having never found that any acid, however dense, produced an im- mediate explosion, I once poured 6 dr. of concentrate acid on 50 gr. of the powder. An explosion, nearly at the instant of contact, was effected : I was wounded severely, and most of my apparatus destroyed. A quantity also of the gas I had previously prepared, was lost by the inadvertency of a person who went into my laboratory while I was confined by the consequences of this discouraging accident. But should any one be desirous of giving the gas a further examination, I again repeat, that as far as I am enabled to judge, it may with safety be prepared, by pouring 3 dr. of sulphuric acid diluted with the same quantity of water, on 50 gr. of the powder and then applying the flame of a candle till gas begins to be extricated. The only attempt I have made to decompose it, was by exposing it to copper and ammonia; which, during several weeks, did not effect the least alteration. §17.1 shall now conclude, by observing, that the fulminating mercury seems to be characterised by the following properties. It takes fire at the temperature of 368 Fahrenheit ; explodes by friction,-^ by flint and steel, and by being thrown into concentrate sulphuric acid. It is equally inflammable under the exhausted receiver of an air-pump, as surrounded by atmospheric air; and it detonates loudly, both by the blow of a hammer, and by a strong electrical shock. Notwithstanding the * Priestley on Air, vol. 2, p. 88. Birra. 1790- 1 Consequently it should not be inclosed in a bottle with a glass stopper. — Orig. 662 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. composition of fulminating silver, and of fulminating gold, differ essentially from that of fulminating mercury, all 3 have some similar qualities. In tremendous effects, silver undoubtedly stands first, and gold perhaps the last. The effects of the mercurial powder and of gunpowder, admit of little comparison. The one exerts, within certain limits, an almost inconceivable force : its agents seem to be gas and caloric, very suddenly set at liberty, and both mercury and water thrown into vapour. The other displays a more extended but inferior power : gas and caloric are, comparatively speaking, liberated by degrees ; and water, according to Count Rumford, is thrown into vapour.* Hence it seems, that the fulminating mercury, from the limitation of its sphere of action, can seldom if ever be applied to mining ; and, from the immensity of its initial force, cannot be used in fire- arms, unless in cases where it becomes an object to destroy them ; perhaps where it is the practice to spike cannon it may be of service, because I apprehend it may be used in such a manner as to burst cannon, without dispersing any splinters. The inflammation of fulminating mercury by concussion, offers nothing more novel or remarkable than the inflammation, by concussion, of many other sub- stances. The theory of such inflammations has been long since exposed by the celebrated Berthollet, and confirmed by Messieurs Fourcroy and Vauquelin: yet I must confess I am at a loss to understand, why a small quantity of mercurial pow- der made to detonate by the hammer, or the electric shock, should produce a report so much louder than when it is inflamed by a match, or by flint and steel. It might at first be imagined, that the loudness of the report could be accounted for, by supposing the instant of the inflammation, and that of the powder's confine- ment between the hammer and anvil, to be precisely the same; but when the elec- trical shock is sent through or over a few grains of the powder, merely laid on ivory, and a loud report is the consequence, I can form no idea of what causes such a report. The operation by which the powder is prepared, is perhaps one of the most beau- tiful and surprising in chemistry ; and it is not a little interesting to consider the affinities which are brought into play. The superabundant nitrous acid of the mer- curial solution, must first act on the alcohol, and generate ether, nitrous etherized gas, and oxalic acid. The mercury unites to the last 2 in their nascent state, and relinquishes fresh nitrous acid, to act on any unaltered alcohol. The oxalic acid, though a predisposing affinity seems exerted in favour of its quantity, is evidently not formed fast enough to retain all the mercury ; otherwise, no white fumes, dur- ing a considerable period of the operation, but fulminating mercury alone, would be produced. Should any doubt still be entertained of the existence of the affinities which have * See Phil. Trang. for 1797, P- 222. The hard black substance mentioned by the Count, as remain- ing after the combustion of gunpowder, must, I believe, have been an alkaline sulphuret, mixed chiefly with sulphite and carbonate of potash. The conjecture that it is white when first formed, is certainly just, as my experiment with the glass globe evinced. — Orig. VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 663 been called predisposing or conspiring, a proof that such affinities really exist, will I think be afforded, by comparing the quantity of oxalic acid which can be gene- rated from given measures of nitrous acid and alcohol, with the intervention of mercury, and the intervention of other metals. For instance, when 2 measured ounces of alcohol are treated with a solution of 100 gr. of nickel in a measured ounce and a half of nitrous acid, little or no precipitate is produced ; yet, by the addition of oxalic acid to the residuary liquor, a quantity of oxalate of nickel, after some repose, is deposited. Copper affords another illustration: 100 gr. of copper, dissolved in a measured 14? oz. of nitrous acid, and treated with alcohol, yielded me about 18 gr. only of oxalate; though cupreous oxalate was plentifully generated, by dropping oxalic acid into the residuary liquor. About 21 gr. of pure oxalic acid seem to be produced, from the same materials, when 100 gr. of mercury are inter- posed. (See § 14). Besides, according to the Dutch paper, more than once referred to, acetous acid is the principal residue after the preparation of nitrous ether. How can we explain the formation of a greater quantity of oxalic acid, from the same materials, with the intervention of 100 gr. of mercury, than with the intervention of 100 gr. of copper, otherwise than by the notion of conspiring affinities, so analogous to what we see in other phenomena of nature? I have attempted, without success, to communicate fulminating properties, by means of alcohol, to gold, platina, antimony, tin, copper, iron, lead, zink, nickel, bismuth, cobalt, arsenic, and manganese; but I have not yet sufficiently varied my experiments, to enable me to speak with absolute certainty. Silver, when 20 gr. of it were treated with nearly the same proportions of nitrous acid and alcohol as 100 gr. of mercury, yielded, at the end of the operation, about 3 gr. of a gray precipitate, which fulminated with extreme violence. Mr. Cruick shank had the goodness to repeat the experiment: he dissolved 40 gr. of silver in 2 oz. of the strongest nitrous acid diluted with an equal quantity of water, and obtained, by means of 2 oz. of alcohol, 60 gr. of a very white powder, which fulminated like the gray precipitate above described. It probably combines with the same principles as the mercury, and of course differs from Mr. Berthollet's fulminating silver, alluded to in p. 662. I observe, that a white precipitate is always produced in the first instance, and that it may be preserved, by adding water, as soon as it is formed; otherwise, when the mother liquor is abundant, it often becomes gray, and is re dissolved. p. s. Since the preceding pages were written, I have been permitted by Lord Howe, Lieut. General of the Ordnance, to make the following trials of the mer- curial powder, at Woolwich, in conjunction with Col. Blomefield, and Mr. Cruickshank. Exper. 1. From the manner in which the screw of the gun-breech, mentioned in § 5, had acted on the barrel, it was imagined, that by bursting an iron case, exactly fitted to the bore of a cannon, its sudden enlargement might make many flaws, and split the piece, without dispersing any splinters. In conformity to this 664 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. opinion, a cast iron case was constructed, with a cylindrical chamber, of equal length and diameter, calculated to hold 3± oz. Troy of the mercurial powder. The case, being firmly screwed together, was charged through its vent-hole, and introduced into a 12-pounder carronade, the bore of which it exactly fitted. The powder was then inflamed, with proper precautions. The gun remained entire, but the case divided ; the portion forming the upper surface of the chamber, was expelled in one mass; that adjoining the breech, which constituted the rest of the chamber, was cracked in every direction, and in part crumbled; yet it was so wedged into some indentations which the explosion had made in the sides of the piece, that the fragments were not removed without great labour. Exper. 2. Another cast iron case was prepared, of the same size as the former, with a chamber also cylindrical, but wrought in a transverse direction, and of a greater length than diameter; the thickness of metal at each extremity not being more than ± of an inch. This case was filled with nearly 5 oz. Troy of the mer- curial powder, and placed in the same carronade. Three 12-pound shot were next introduced, and brought into close contact with the upper surface of the case, as well as with each other. The gun a 2d time withstood the explosion: the case was divided across the middle of the chamber, into 2 equal parts; that adjoining the breech was, as in the former experiment, much flawed, and left immoveable; that nearest to the muzzle was also much flawed, but driven out with the shot. All the 3 shot were broken; the 2 lower being divided into several pieces, and the upper 1 cracked through the centre. The report was so feeble, in both experiments, that an inattentive person, I am confident, would not have heard it at the distance of 200 yards. Exper. 3. It was found so difficult to extract the fragments of the case remain- ing in the carronade, after the last experiment, that a channel was drilled through them, to the vent-hole of the piece. It was then charged with 6 oz. Troy of the mercurial powder, made up as a cartridge, which did not occupy above 4- of the diameter of the bore. A wad was placed over the powder, dry sand superadded, to fill all vacuities, and the gun filled to the muzzle with 2 12-pound shot. A block of wood was set at a small distance, to receive the impression of the shot, and the powder was inflamed as usual. The carronade still resisted. One of the shot was split into 2 pieces; and the block of wood was driven to a considerable distance, but not penetrated by the shot above the depth of 1 inch. The report was somewhat louder than the former ones. In all the 3 instances, a considerable recoil evidently took place. I presume therefore, that in the first experiment related in § 5, there must have been a recoil, though too trifling to be observed; and in the instances where the gun and the proof were burst, it was not so much to be expected. Exper. 4. Finding that the carronade, from the great comparative size of its bore to that of its length, required a larger quantity of mercurial powder to burst it than we were provided with, we charged a -L-pounder swivel with J-fr oz. avoir- dupois of the mercurial powder, (the service charge of gunpowder being 3 oz.) VOL. XC.] PHILOSOPHICAL TRANSACTIONS. - 665 and a ^-pound shot between 2 wads. The piece was destroyed from the trunnions to the breech, and its fragments thrown 30 or 40 yards. The ball penetrated 5 inches into a block of wood, standing at about a yard from the muzzle of the gun; the part of the swivel not broken, was scarce, if at all, moved from its original position. Exper. 5. I oz. avoirdupois of the mercurial powder enclosed in paper, was placed in the centre of a shell 4.4 inches in diameter, and the vacant space filled with dry sand. The shell burst by the explosion of the powder, and the fragments were thrown to a considerable distance. The charge of gunpowder employed to burst shells of this diameter, is 5 oz. avoirdupois. Exper. 6. A sea grenade, 3.5 inches diameter, charged like the shell in the last experiment, was burst into numerous fragments, by \oz. avoirdupois of the mer- curial powder. The fragments were projected with but little force, and only to the distance of 8 or 10 yards. The charge of gunpowder required for grenades of this size, is 3 oz. Exper. 7. A sea grenade, of the same diameter as the last-mentioned, and charged in the like manner, with -l oz. avoirdupois, or 574- gr., of the mercurial powder, was split into 2 equal pieces, which were not thrown 10 inches asunder. The report in the last 4 experiments was very sharp, but not loud in proportion. It seems, from the manner in which the swivel was burst, in the 4th experiment, that a smaller charge would have been sufficient for the purpose. We may there- fore infer, both from this instance and from the 2d experiment made with the gun, in § 5, that any piece of ordnance might be destroyed, by employing a quantity of the mercurial powder equal in weight to half the service charge of gunpowder; and from the 7th and last experiment we may also conclude, that it would be possible so to proportion the charge of mercurial powder to the size of different cannons, as to burst them without dispersing any splinters. But the great danger attending the use of fulminating mercury, on account of the facility with which it explodes, will probably prevent its being employed for that purpose. In addition to the other singular properties of the fulminating mercury, it may be observed, that 2 oz. inflamed in the open air, seem to produce a report much louder than when the same quantity is exploded in a gun capable of resisting its action. Mr. Cruickshank, who made some of the powder, by my process, remarked that it would not inflame gunpowder. In consequence of which, we spread a mix- ture of coarse and fine grained gunpowder on a parcel of the mercurial powder; and after the inflammation of the latter we collected most, if not all of the grains of gunpowder. Can this extraordinary fact be explained by the rapidity of the com- bustion of fulminating mercury? or is it to be supposed, as gunpowder will not explode at the temperature at which mercury is thrown into vapour, that sufficient caloric is not extricated during this combustion? From the late opportunity I have had of conversing with Mr. Cruickshank, I find that he has made many accurate experiments on gunpowder; and he has per- VOL. XVIII. 4 Q 666 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. mitted me to state, that the matter which remains after the explosion of gunpowder, consists of potash united with a small proportion of carbonic acid, sulphate of pot- ash, a very small quantity of sulphuret of potash, and unconsumed charcoal. That 100 gr. of good gunpowder yield about 53 gr. of this residuum, of which 3 are charcoal. That it is extremely deliquescent, and when exposed to the air soon ab- sorbs moisture sufficient to dissolve a part of the alkali ; in consequence of which, the charcoal becomes exposed, and the whole assumes a black or very dark colour. Mr. Cruickshank likewise informs me, that after the combustion of good gun- powder under mercury, no water is ever perceptible. References to the Figures of the Glass Globe, §c. mentioned in § 7. — a, in pi. 11, fig. 1, is a ball or globe of glass, nearly half an inch thick, and 7 inches in diameter. It has 2 necks, on which are cemented the brass caps b, c, each being perforated with a female screw, to receive the male ones d, e j through the former a small hole is drilled j the latter is furnished with a perforated stud or shank g. By- means of a leather collar h, the neck c can be air-tightly closed. When a portion of the powder is to be exploded, it must be placed on a piece of paper, and a small wire laid across the paper, through the midst of the powder : the paper being then closed, is to be tied at each end to the wire, with a silken thread, as shown at i. One end of this wire is to be fastened to the end of the shank G, and the screw d inserted to half its length into the brass cap bj the other end of the wire, a, by means of the needle k, is to be drawn through the hole r. The screw s being now fixed in its place, and the wire drawn tight, it is to be secured, by pushing the irregular wooden plug l into the aperture of the screw d, taking care to leave a passage for air. The stop-cock m, the section of which is shown at n, is now to be screwed on to the part d, which is made air-tight by the leather collar b. The glass tube o is bent, that it may more conveniently be introduced under the receiver of a pneumatic apparatus, p shows the manner of connecting the glass tube with the stop-cock. Meteorological Journal, kept at the Apartments of the R. S. By order of the President and Council, p. 23Q. 1799- Jan. Feb. Mar. April May June JuLy Aug. Sept. Oct. Nov. Dec. Six's Therm, without rt bO JJ-S 50 56 56 59 70 77 77 73 72 63 58 50 Whole ■S-e 3j* 20 18 28 28 36 43 48 47 44 35 32 17 _5 8 S S 50 56 56 56 70 77 77 72 71 63 58 50 23 22 28 30 40 49 52 51 46 35 32 17 p.sjfsi Thermometer within. s.fip S"3> 55 60 62 58 62 67 68 66 67 63 60 57 41 42 49 47 54 58 62 62 60 55 53 43 49-0 51.0 53.6 54.3 58.7 62.1 64.9 63.3 62.1 59.5 56.1 50.4 Barometer.* Hygrometer. Rain. 1 test ht. St ht. an ht. BjS <§.£ «J3 SS .£H S bO v ho ? 2 »-5 8 S 8 M«j bO >- o> i-3 '5 S v Inc. 1 Inc. Inc. O -c J3 " J3 0 0 0 Inc. 30.43 29-25 29-98 86 61 79-1 0.949 30.26 28.88 29.70 92 57 75.2 2.235 30.23,29.31 29-84 0.433 30.231 28.75 2962 1.671 30.38 29.33 29-84 1.749 30.41 j 29. 18 30.04 0.552 30.18,29.22 29-82 2.913 30.12 29.26 29-81 78 45 59.8 2.209 30.40 29-04 29.82 83 45 63.9 2.824 30.37 29.34 29.80 88 53 '69.4 2.191 30.40 28.82 29-87 87 55 \7l.9 1.587 30.54 29.1929.93 1 85 60 71.1 0.349 1 2984 1 19.662 '479 I 48.5 57.1 * The quicksilver in the basin of the barometer is 81 feet above the level of low water spring tides at Somerset-house. VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 66*7 XII. On Double Images caused by Atmospherical Refraction, By Wm. H. Wollaston, M. D., F. R. S. p. 23Q. In some of the last volumes of the Philos. Trans, there have been related many instances of strong atmospherical refraction, by which, objects seen near the horizon have appeared inverted, and the horizon itself either elevated or depressed. Mr. Huddart first took notice of a distinct image, inverted beneath the object itself; and, in the Philos. Trans, for 1797, has described several such appearances, accom- panied with an optical explanation, where he shows that the lowest strata of the air were at the time endued with a weaker refractive power, than others at a small elevation. In the volume for 1799> Mr. Vince has given an instance, fig. 1, where erect, as well as inverted images were visible above, instead of beneath, the objects themselves; and, by tracing the progress of the rays of light, in a manner similar to Mr. Huddart's, concludes that these phenomena arose from " unusual variations" of increasing density in the lower strata of the atmosphere. In the volume for 1795, Mr. Dalby mentions having seen " the top of a hill appear detached, for the sky was seen under it." In this case, as well as in the preceding, it is probable that inversion took place, and that the lower half of the portion detached was an inverted image of the upper, as the sky could not be seen beneath it, but by an inverted course of the rays. Since the causes of these peculiarities of terrestrial refraction have not received so full an explanation as might be wished, I have endeavoured, 1st. To inves- tigate theoretically the successive variations of increasing or decreasing density to which fluids in general are liable, and the laws of the refractions occasioned by them. 2dly. To illustrate and confirm the truth of this theory, by experiments with fluids of known density. And lastly, to ascertain, by trial on the air itself, the causes and extent of those variations of its refractive density, on which the in- versions of objects, and other phenomena observed, appear to depend. The general laws may be comprised in three propositions. Prop. 1. If the density of any medium varies by parallel indefinitely thin strata, any rays of light moving through it in the direction of the strata, will be made to deviate during their passage, and their deviations will be in proportion to the incre- ments of density where they pass. For each ray will be bent towards the denser strata, by a refracting force proportioned to the difference of the densities above and below the line of its passage; and as their velocities are the same, and there- fore the times of action of the forces equal, the deviations will be as the refracting forces, i. e. as the increments of density. Prop. 2. When 2 fluids of unequal density are brought into contact, and unite by mutual penetration; if the densities at different heights be expressed by ordi- nates, the curve which terminates these ordinates will have a point of contrary flexure. For the straight lines da, rn, pi. 11, fig. 2, which terminate the ordinates rx, dy, of uniform density, will be parallel, and, if not united by contrary curva- 4a 2 668 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. ture, some straight line of union, as ao, must be supposed. But, from whatever cause the first line ao is inferred, by the same cause other intermediate lines mp, tq, &c. will be produced, and curves defm, mtsr, will be ultimately formed, having a point of contrary flexure at m. The form of the curve does not appear to admit of accurate investigation, nor is it of importance to the subsequent reasoning if wholly unknown. We may however form some judgment of its nature; for whe- ther the densities depend on different specific gravities of different fluids, or on un- equal temperatures of different portions of the same fluid, the curves will be nearly alike. In each of these cases, to whatever small distance pc, fig. 3, the mutual attraction is sufficient to occasion intimate union of the fluids, the density mn of the mixture will be an arithmetic mean; and, for the same reason, at any inter- mediate smaller distances, there will be a series of arithmetic means ef, gh, &c. interposed, and the line ao, uniting the ordinates, will be straight. By progressive effect of this attraction, and successive interpolations, in fig. 2, curves defm, rstm, will be formed; of which the straight lines mp, tq, &c. are tangents. The at- tracting distances np, oq, &c. are subtangents; and if it be admitted that these are every where equal, the curves so produced are logarithmic, and the increment of the ordinate greatest at m, where they meet. Prop. 3. If parallel rays pass through a medium varying according to the pre- ceding proposition, those above the point of contrary flexure will be made to diverge, and those below the same point will converge, after their passage through it. For, since the deviation of each ray depends on the increment of density where it passes, and since the increment of density is greatest at the point of contrary flexure, any rays, as ab, fig. 4, passing near to that point, will be refracted more towards the denser medium than those at cd, which move in a higher stratum, and will diverge from them, but will be refracted towards and meet those at ef, which pass nearer to the denser medium, where the increments of density are also less. Cor. Hence, adjacent portions of the converging rays will form a focus, beyond which they will diverge again ; and the varied medium will produce effects similar to those caused by a medium of uniform density*, having a surface similar to the curve of densities, since convergence or divergence will be produced, according as the curve of densities is convex or concave; consequently, by tracing backwards, to the extremities of an object, the progress of the visual rays, or axes of the pencils re- ceived by the eye, it will be manifest that, any object seen through the inclined concave part rm, fig. 6, would appear elevated, erect, and somewhat diminished. An object seen through md, where it is convex and inclined, would be elevated; and if situated beyond the focus of visual rays from the eye, it would appear in- * In the varied medium, be and Dm, fig. 5, the corresponding increments of the abscissa and or- dinate, are to each other as radius to the tangent of the angle c. Therefore the tangent of deviation, which is as the increment of the ordinate, varies as the tangent of the angle c. So also, in the uniform medium, since the sines of refraction and incidence are in a given ratio, their differences will bear a given ratio to either of them ; and when the angles are small, the tangent of deviation will vary as the tangent of incidence, or as the tangent of the angle c, which is equal to it. — Orig, VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 669 verted. The magnitude would depend on the relative distances of the eye and object. Below the point d, where the curve terminates, vision would be direct, so that an object might be situated so as to be seen in all the 3 ways at the same time, direct at o, inverted at i, and erect again at a. I consider the foregoing propositions as applicable to all cases of varying density, whether occasioned by mutual solution of different fluids, or partial rarefaction of the same fluid; and by trial of various fluids, however different in density, or even in viscidity, I find that the refractions observe a law agreeable to the theory, as will appear by the following experiments. Exper. 1. Into a square phial containing a small quantity of clear syrup, I put about an equal quantity of water, in such a way that it floated on the surface of the syrup, without mixing. For a short time, the stratum of union was so thin that nothing could be distinctly seen through it. But soon, by mutual penetration of the water and the syrup, the effects represented at a, fig. 7, were produced. Through the syrup, a word written on a card placed behind was seen erect, and in its place; through the adjacent variable medium, an inverted image was visible above the trite place; and also above that a 2d image of the same object appeared erect. When these appearances are first discernible, the variations of density are so great, that the object to be looked at may be in contact with the phial; but when the variations of density become more gradual, and so the focus more distant, any object so near is only elongated, and requires to be removed an inch or 2, to be seen inverted. Exper. 2. Over the surface of the water, in the same phial, I next put about the same measure of rectified spirit of wine. At the stratum where the water and spirit united, the appearances were the same; but since the refractive power of spirit exceeds that of water, the true place of the object was seen uppermost; the inverted and erect images are below. Fig. 7> b. When an oblique line der is viewed through any variable medium so made, it appears bent into different forms, according to its situation with respect to focal distance. If it be at the distance of the principal focus, one point of it is dilated into a vertical line, as lm. Fig. 8, a. If beyond that focus, the portion lm is inclined backwards, being an inverted image of dl; and mn is another image of ihe same portion seen erect. Fig. 8, b. On this account, it becomes a convenient object for ascertaining the state of any medium under examination. In these experiments, the appearances continue many hours, even with spirit of wine; with syrup, 2 or 3 days; with acid of vitriol, 4 or 5; with a solution of gum arabic, much longer; but though their disposition to unite is so different, yet the appearances produced are the same in all. The refraction is greatest nearly in the plain of original contact of the fluids, diminishing from thence both upwards and downwards. The exact rate of diminution above or below this point, I had no means of measuring, with the accuracy that would be requisite for determining the nature of the curves of density formed according to the first proposition. But ^70 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. the truth of the 2d proposition appeared capable of confirmation by experiment* for the deviation of a ray is there said to depend on the increment of density and time of the ray's passage, jointly; accordingly the deviation caused by a given increment should be in proportion to the extent of the medium. In order to try what effect a greater extent of medium would produce. Eocper. 3. I made a rectangular glass vessel, of which the sides were in the ratio of 10 to 30.6; and, having put into it some clear syrup, with water on its surface, I measured the greatest refractions through it in both directions, and found them in the ratio of 10 to about 29. In another vessel, of which the sides were as 10 to 40.4, the refractions were, on an average, as 1 to 4. Being now fully satisfied of the effect of different fluids, I made the following experiment, by which it appears, that the variations of density occasioned by difference of tem- perature between adjacent strata of the same fluid, follow a similar law. Exper. 4. Having put some cold water into a square vessel, I covered its surface with a piece of writing paper perforated with a few small holes, and then filled the vessel cautiously with boiling water. The paper nearly prevented any mixture of the hot and cold water; but, by floating gradually up, left them to communicate their heat by contact alone. While they were in this state, I examined the ap- pearance of remote objects through the varied medium, and found, that when my eye was removed 4 or 5 feet from the vessel, the effects were the same as in the pre- ceding experiments with different fluids; above any object viewed through the cold water, I could distinguish 2 images of it, the one inverted, the other erect, as usual ; but these appearances did not continue more than 5 or 6 minutes. Having thus established, by experiments sufficiently varied, that the contiguity of 2 fluids of unequal density is capable of occasioning all the appearances that have been observed, I shall proceed to show by what means the air may be made to exhibit similar phenomena. Exper. 5. I heated a common poker red-hot, and held it so as to look along the side of it, at a paper 10 or 12 feet distant. The rarefaction occasioned by it caused a perceptible refraction, to the distance of about £ of an inch from the side of the poker. A letter seen more distant from it appeared as usual ; within that distance there was a faint image of it reversed; and still nearer to the poker was a 2d image direct, and as distinct as the object itself, but somewhat smaller, as in fig. 9, in which a section of the atmosphere surrounding the poker is represented. At the bottom and sides it is nearly circular; but upwards the circular form is lost in un- dulations, occasioned by the rapid ascent of the rarefied air. The greatest de- viation produced in this case measured about 4 a degree. Exper. 6. By a red-hot bar of iron, 30 inches long, the refractions were much greater, the extreme deviations amounting to full 1^- degree. The refractions observed in these experiments may, at first view, be thought greater than could be caused by difference of temperature alone, being in one in- stance more than double the greatest horizontal refraction of the heavenly bodies; VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 67 1 in which case, as the rays enter from a vacuum, the greatest possible effect of the at- mosphere might be expected. But it must be remembered, that when a star appears in the horizon, its rays intersect the superior strata of the atmosphere at an inclina- tion of several degrees, and that they pass but once through the variations from rarity to density; but, on the contrary, that in the experiments with red-hot iron, the rays may pass actually in the direction of the strata, and that they are re- fracted, not only by their entrance from the denser into the rarer medium, but the effect is doubled, since the refraction caused by their emergence is equal to that produced by their incidence. Though a stratum of air, heated by these means to so great a degree, affords an erect, as well as an inverted, image of objects seen through it, the more moderate warmth communicated to it from bodies heated by the action of the sun on them, seems insufficient to produce both images; but the inverted image may generally be seen, when the sun shines on a brick wall, or other dark-coloured surface. While the eye of the observer is placed nearly in a line with the wall, if another person, at 30 or 40 yards distance, extends any object towards the wall, an image similar to it will appear to come out to meet it. It would be difficult to ascertain with accuracy the degree of rarefaction capable of showing this appearance, but it may be of some use to future observers, to mention the different degrees of heat which I observed. In one instance, a thermometer in contact with the wall, stood at g6°; but, at •§- of an inch distance, 82°. One morning, when the sun shone bright, I examined the temperatures and refraction produced at the surface of a deal bar painted green, about 8 feet long. A small thermometer in contact with the bar, rose to o6°; at -± of an inch distance, it stood at 73°. The re- fraction at the same time exceeded 20 minutes. To explain why red-hot iron occasions 2 images, while solar heat produces but 1, I imagine that the intense heat in the former case rarefies the air for some small distance uniformly, and thus affords the same series of variations as between other fluids of uniform density ; but that, in the latter, the heat is conveyed off as fast as it is generated ; so that, as there is no extent of medium uniformly rare, the densities corresponding to the concave portion rm, fig. 6, of the curve before described, do not take place, but the phenomena occasioned by the convex part md are alone produced. It must be remarked, that the vertical position of the surface contributes greatly to increase the effect; for since the heated air rises in the direction of the surface, its ascent has in this case no tendency to blend it with the adjacent denser strata, and hence very different degrees of density take place in the thickness of ^ of an inch ; so that, as the increments of density are great, the refractions will be proportionally so ; but where the heated surface is horizontal, the ascent of the rarefied air into the superincumbent denser strata renders the variations far more gradual; consequently a heated surface of far greater extent must be re- quisite, to produce equal refraction. However, over extensive plains, when the sun shines,, some degree of inversion 671 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. is very frequently to be seen ; but the inverted images are rarely well defined, unless over a very even surface. One of the best situations for this purpose, is over a level open road, with a gentle breeze blowing across it. A current of air brings a cool stratum more closely in contact with the heated surface; and, since refraction depends on the increment or difference of density in a given small space, a very moderate breeze will thus render inversion more perceptible; but a strong wind will reduce the temperature of the surface, and may make the heated stratum too thin for any object to be seen through it from a distance. In one instance, when I saw a refraction of about 9 minutes, at the distance of -y of a mile, a thermometer in the sand was 101°; at 4 inches above, 82°; and at 1 foot above, 760. Over water the evenness of the surface is favourable to the production of such appearances; but, since the action of the sun is weak on a body so transparent, a far greater extent of surface is requisite to produce any perceptible inversion. Being at Bognor one bright morning, when the sea was calm, I had an opportunity of observing the appearance of Selsea Bill, about 6 miles distant. The whole extent of coast, when viewed with a pocket telescope magnifying about 16 times, appeared inverted from one end to the other; and the lower part of a brick house on the shore, was seen as distinct as the house itself. I judged the quantity of refraction, in this case, to be about 2 minutes of a degree. This state of atmosphere appears to be not very uncommon ; for, at Shanklin Chine, in the Isle of Wight, a few days preceding, similar appearances were visible in several directions, but I neg- lected to make any estimate of the .quantity of refraction. In the instance of the inverted vessel seen by Mr. Huddart, (Phil. Trans, for 1797, %• 3) at the distance of 8 miles, the refraction seems to have been about 3'. All the appearances described by him, I am inclined to think, arose from difference of temperature alone. He offers a conjecture, that evaporation might occasion the lower strata of the atmosphere to have a weaker refractive power; but, from the following ex- periments, it seems to have a contrary effect. Exper. 7. I took a plate of glass, and, while looking along the surface, I poured on it a small quantity of ether. A line on the opposite wall, appeared instantaneously elevated many minutes, and at times above 4- a degree. This fluid being the most volatile, and most soluble in the atmosphere, of any known liquid, produces the greatest effect; since the cold, during evaporation, conspires with the ether dis- solved in the air, to increase the refractive power. Rectified spirit of wine also produces, from the same cause, a very considerable effect. Exper. 8. By moistening a board, 5 feet in length, with alcohol, and observing the elevation of an object viewed over its surface, I found the refraction to be about 15'. Exper. 9. I next made a similar experiment with water itself. Of this, the effect was barely visible, when tried in the same way ; but, by means of a surface of 10 feet, and by viewing a luminous point at a greater distance, the refraction became evident, and the object elevated above 3 minutes. In the course of these VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 673 experiments, I tried whether confining the saturated atmosphere, by boards on each side, would vary the effect, and found the refraction in all cases much lessened; and, when water was used, it became imperceptible; but as soon as the boards were removed, and a free current allowed to pass across, the full effect was again produced. The reason of this difference appears to be, that the quicker evaporation increases the degree of cold, and the current brings greater differences of density contiguous. This state of rapid evaporation will fully account for the phenomenon witnessed by Mr.Latham, who has described (in Phil. Trans, for 179^,) an extraordinary elevation of the opposite coast of France, so as to be seen from the beach at Hastings, and other parts of Sussex. There is a fact of the same kind stated by De la Lande, (Astron. torn. 2,) who says that the mountains of Corsica, though at the distance of more than 100 miles, are occasionally visible from Genoa. It is probably owing to the same cause, that other objects have been sometimes seen, at such distances that we should expect them to be intercepted by the curvature of the earth ; for it is evident, that whenever the evaporation over each mile of surface occasions a refraction of about 1 minute, the rays receive a curvature equal to that of the ocean, so that its surface will appear flat, and the spherical form of the earth will not obstruct horizontal vision of objects at any distance. It still remained to explain the phenomena seen by Mr. Vince, as I had not hitherto made an atmosphere capable of exhibiting images inverted, as well as ele- vated, by increased density. For, in the refractions produced in the 7th, 8th, and 9th experiments, by evaporation at an exposed surface, I observed the effect was always greatest in contact with the evaporating surface ; any lower point a, fig. 10, appeared brought nearer to a higher point c, by the pencils of rays from a being more refracted at b, than the pencil from c was refracted at d. Therefore, any rays passing from the eye at e, as a point, through b and d, would be made to diverge to a and c; consequently visual rays could not, under these circumstances, intersect each other, and no objects could appear inverted. But, whenever the lowest strata of the air becomes saturated with moisture, the variations between the saturated stratum and the incumbent atmosphere of the common density, will follow a law similar to what is found at the confines of other fluids of unequal density; hence, inversion will become visible, as there will be a point below which the increment of density will decrease, and where the refractions will consequently be less, though through a denser medium. Exper. 10. To produce these appearances, I procured a trough of thin deal, 5 feet long, 1 inch wide, with sides 24- inches high, and closed the extremities of it with glass. A section of it is given in fig. 1 1 . When the bottom was wetted with ether, the greatest refraction was, at intervals, more than %■ of an inch from the bottom of the trough ; and beneath this height I saw a 2d image inverted, when my eye was removed to 14 or 15 feet distance, and the object at about 70 feet. The focus seemed at the same time to be about 9 feet distant. There was VOL. XVIII. , 4 R ()74 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. not depth enough of uniformly saturated atmosphere for the object itself to be seen through it, but its true place, compared with that of the images, is represented at a. Exper. 11. When I made use of rectified spirit in the same apparatus, I had also sufficient proof that the laws of evaporation would admit of such appearances being produced; for the same object now appeared curved downwards, as in fig. 12, so that rays nearer to the bottom were manifestly less refracted than such as passed at some distance above. A degree of convergency must therefore have been pro- duced, though the distance at which the rays would meet, was beyond that of my eye, and circumstances would not admit of my removing beyond 35 feet. The evaporation of water could not be expected to produce any sensible effect of this kind, in so short a space ; but, in a view of some miles extent, there can be no doubt, from the foregoing experiments, that evaporation from the surface of the sea, in such a state of the atmosphere as would allow the lower strata to be saturated, is capable of occasioning all the phenomena which have been described, and probably was the cause of those which Mr. Vince observed. Since heat alone tends to depress objects, and evaporation produces apparent elevation, it is proba- ble, that in the instance of refraction related by Mr. Dalby, Phil. Trans, for 1795, the heat of the sun was the principal agent, and that the moisture rather tended to counteract than assist its action. Simple inversion may generally be seen, when the sun shines on a dry even road of -f or ± mile extent ; but when the ground has been wet, I have very rarely seen it, and have even failed of discerning it, when the heat has been sufficient to raise a steam from the ground. The follow- ing experiment shows that it is not to be expected but by very great extent of surface. Exper. 12. I placed a dark-coloured board in the sunshine, and, having examined the refraction along its surface, I made a wet lipe along it, with a sponge dipped in boiling water. Notwithstanding this additional heat, the refraction, in the di- rection of the wet line, was far less than over the rest of the board, though I took care to observe the effect before the surface could be cooled again by evaporation. I should therefore expect the depression of the horizon at sea, where the refrac- tion occasioned by heat must always be counteracted by evaporation, never to exceed a few minutes ; and that any one in a situation commanding a view of the sea, by attention to the various degrees of the dip of the horizon under different circumstances, might soon form some estimate of the proper allowance to be made, for brightness of the sun at the time of an astronomical observation, or for differ- ence of temperature between the sea and air. Having now examined the several peculiarities of refraction which I proposed for consideration, I shall, in few words, recapitulate the purport of the foregoing pages. According to the theory here given, there appear to be 2 opposite states of the atmosphere, either of which may occasion objects to be seen doubled or tripled, since both increase and decrease of its density ; when partial, produce simi- VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 675 lar effects. It has been explained, 1st. Why air heated by the moderate warmth of the sun's rays, occasions objects to appear doubled and inverted. 2dly. Why rarefaction, by a higher degree of heat, gives an additional image, which is not inverted. 3dly. In what state of evaporation the increase of the air's density brings distant objects into view by unusual elevation. 4thly. Under what circum- stances evaporation may also produce an inverted image less elevated. And it is probable, that the same reasoning will afford a ready explanation to other varieties of terrestrial refraction, that may have been, or may hereafter be observed. XIII. Investigation of the Powers of the Prismatic Colours to Heat and Illuminate Objects ; with Remarks, that prove the Different Refrangibility of Radiant Heat, To which is added, an Inquiry into the Method of Viewing the Sun advan- tageously, with Telescopes of Large Apertures and High Magnifying Powers. By Wm. Herschel, LL. D., F. R. S. p. 255. It is sometimes of great use in natural philosophy, to doubt of things that are commonly taken for granted ; especially as the means of resolving any doubt, when once it is entertained, are often within our reach. We may therefore say, that any experiment which leads us to investigate the truth of what was before admitted on trust, may become of great utility to natural knowledge. Thus, for instance, when we see the effect of the condensation of the sun's rays in the focus of a burning lens, it seems to be natural to suppose, that every one of the united rays contributes its proportional share to the intensity of the heat produced ; and we should probably think it highly absurd, if it were asserted that many of them had but little concern in the combustion, or vitrification, which follows, when an object is put into that focus. It will therefore not be amiss to notice what gave rise to a surmise, that the power of heating and illuminating objects, might not be equally distributed among the variously coloured rays. In a variety of experiments I have occasionally made, relating to the method of viewing the sun, with large telescopes, to the best advantage, I used various com- binations of differently-coloured darkening glasses. What appeared remarkable was, that when I used some of them, I felt a sensation of heat, though I had but little light ; while others gave me much light, with scarce any sensation of heat. Now, as in these different combinations the sun's image was also differently co- loured, it occurred to me, that the prismatic rays might have the power of heating bodies very unequally distributed among them ; and, as I judged it right in this respect to entertain a doubt, it appeared equally proper to admit the same with re- gard to light. If certain colours should be more apt to occasion heat, others might, on the contrary, be more fit for vision, by possessing a superior illumi- nating power. At all events, it would be proper to recur to experiments for a decision. Experiments on the Heating Power of Coloured Rays. — I fixed a piece of paste- board, ab, pi. u, fig. 13, in a frame mounted on a stand, CD, and moveable on-2 4B2 676 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. centres. In the pasteboard, I cut an opening, mn, a little larger than the ball of a thermometer, and of a sufficient length to let the whole extent of one of the prismatic colours pass through. I then placed 3 thermometers on small inclined planes, ef : their balls being blacked with japan ink. That of No. 1 was rather too large for great sensibility. No. 2 and 3 were 2 excellent thermometers, which my highly esteemed friend Dr. Wilson, late Professor of Astronomy at Glasgow, had lent me for the purpose : their balls being very small, made them of exquisite sensibility. The scales of all were properly disengaged from the balls. I now placed the stand, with the framed pasteboard and the thermometers, on a small plain board, gh ; that I might be at liberty to move the whole apparatus together, without deranging the relative situation of the different parts. This done, I set a prism, moveable on its axis, into the upper part of an open window, at right angles to the solar ray, and turned it about till its refracted coloured spectrum became stationary, on a table placed at a proper distance from the window. The board containing the apparatus was now put on the table, and set in such a manner as to let the rays of one colour pass through the opening in the paste- board. The moveable frame was then adjusted to be perpendicular to the rays coming from the prism ; and the inclined planes carrying the 3 thermometers, with their balls arranged in a line, were set so near the opening, that any one of them might easily be advanced far enough to receive the irradiation of the colour which passed through the opening, while the rest remained close by, under the shade of the pasteboard. By repeated trials, I found that Dr. Wilson's No. 2 and mine, always agreed in showing the temperature of the place where I examined them, when the change was not very sudden : but that mine would require 10 minutes to take a change, which the other would show in 5. No. 3 never differed much from No. 2. 1st Exper, Having arranged the 3 thermometers in the place prepared for the experiment, I waited till they were stationary. Then, advancing No. 1 to the red rays, and leaving the other 2 close by, in the shade, I marked No 1 No< 2 No> 3 down what they showed at different times, as annexed. This, 43£ 43| 43| in about 8 or 10 minutes, gave G§. degrees, for the rising ^ *3| *3| produced in my thermometer, by the red rays, compared to 49| 43£ 43| the 2 standard thermometers. 50 43i l 3 * 2d Exper. As soon as my thermometer was restored to the temperature of the room, which I hastened, by applying it to a large piece of metal No } No that had been kept in the same place, I exposed it again to the 45 45 red rays, and registered its march, along with No. 2 as a stan- dard, which was as annexed. Hence, in 10 minutes, the red rays 51 44| made the thermometer rise 7 degrees. M ** 3d Exper. Proceeding in the same manner as before, in the ^3 * 432, green rays I had as annexed. Therefore in 10 minutes, the 45J 43 green rays occasioned a rise of 3^ degrees. *g ^ 46 42£ VOL. XC.] PHILOSOPHICAL TRANSACTIONS. fyf 4th Exper. I now exposed my thermometer to the violet rays, N* l. N°2. and compared it with N° 2. Here we have a rising of 2°, in 10 44 minutes, for the violet rays. 44| 43£ 45 43 5 th Exper. I now exposed Dr. Wilson's thermometer N° 2 to *J 2- N° 3# the red rays, and compared its progress with N° 3. Here the 46' 44 thermometer, exposed to red, rose in 5 minutes 24 degrees. *?§ 43l ' r 4 & 46J 43| N° 2. N° 3. 44 44 6th Exper. In red rays again. And here the thermometer, 46 44 exposed to red, rose in 5 minutes 4 degrees. *$| 43j 47 43 7*A Exper. In green rays. This made the thermometer rise, N° f N° 3- in the green rays, 14 degree. 44j 43| 44| 43 8* h Exper. Again in green rays. Here the rising, by the green N° 2* N° 3* - 4o 43 rays, was 2 degrees. 44^ 42g 44| 42| From these experiments, we are authorised to draw the following results. In the red rays, my thermometer gave 6^ degrees in the 1st, and 7 degrees in the 2d, for the rising of the quicksilver : a mean of both is 64-. In the 3d experiment, we had 3-A- degrees, for the rising occasioned by the green rays ; from which we obtain the proportion of 55 to 26, for the power of heating in red to that in green. The 4th experiment gave 2° for the violet rays ; and therefore we have the rising of the quicksilver in red to that in violet, as 55 to ]6. A sufficient proof of the accuracy of this determination we have in the result of the last 4 experiments. The rising for red rays in the 5th, is 24/ ; and in the 6th, 4°: a mean of both is 3-f-. In the 7th experiment, we have 14;, and in the 8th, 2° for the rising in green : a mean of these is 14. Therefore, we have the proportion of the rising in red to that in green, as 2/ to 11, or as 55 to 22.4. We may take a mean of the result of both thermometers, which will be 55 to 24.2, or more than 2^ to 1, in red to green ; and about 34/ to 1, in red to violet. It appears remarkable, that the most sensible thermometer should give the least alteration, from the exposure to the coloured rays. But since, in these circum- stances, there are 2 causes constantly acting different ways ; the one to raise the thermometer, the other to bring it down to the temperature of the room, I sup- pose, that on account of the smallness of the ball in Dr. Wilson's N° 1, which is but little more than -f of an inch, the cooling causes must have a stronger effect on the mercury it contains than they can have on mine, the ball of which is half an inch. More accuracy may hereafter be obtained, by attending to the circum- stances of blacking the balls of the thermometers, and their exposure to a more steady and powerful light of the sun, at greater altitudes than it can be had at present j but the experimen ts which have been related, are quite sufficient for 678 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. my present purpose ; which only goes to prove, that the heating power of the pris- matic colours, is very far from being equally divided, and that the red rays are chiefly eminent in that respect. Experiments on the Illuminating Power of Coloured Rays. — In the following examination of the illuminating power of differently-coloured rays, I had 2 ends in view. The first was, with regard to the illumination itself; and the next, with respect to the aptness of the rays for giving distinct vision ; and, though there did not seem to be any particular reason why these 2 should not go together, I judged it right to attend to both. The microscope offered itself as the most convenient instrument for this investigation ; and I thought it expedient to view only opaque objects, as these would give me an opportunity to use a direct prismatic ray, with- out running the risk of any bias that might be given to it, in its transmission through the colouring particles of transparent objects. Exper. 1 . I placed an object that had very minute parts, under a double micro- scope ; and, having set a prism in the window, so as to make the coloured image of the sun stationary on the table where the microscope was placed, I caused the differently-coloured rays to fall successively on the object, by advancing the micro- scope into their light. The magnifying power was 27 times. In changing the illumination, by admitting a different colour, it always becomes necessary to re- adjust the instrument. It is well known, that the different refrangibility of the rays will sensibly affect the focal length of object-glasses ; but, in compound vision, such as in a microscope, where a very small lens is made to cast a length- ened secondary focus, this difference becomes still more considerable. By an attentive and repeated inspection, I found that my object was very well seen in red ; better in orange, and still better in yellow; full as well in green; but to less advantage in blue; indifferently well in indigo, and with more imperfection in violet This trial was made on one of the microscopic objects generally prepared for trans- parent vision: but, as I used it in the opaque way, I thought that others might be chosen which would answer the purpose better ; and, in order to give some variety to my experiments, and to see the effect differently coloured substances might have on the rays of light, I provided the following materials to be viewed. Red paper ; green paper ; a piece of brass ; a nail ; a guinea ; black paper. Having also found that a higher power might be used, with sufficient convenience for the rays of light to come from the prism to the object, I made the microscope magnify 42 times. The appearance of the nail in the microscope, is so beautiful, that it deserves to be noticed; and the more so, as it is accompanied with circumstances that are very favourable for an investigation, such as that which is under our present con- sideration. I had chosen it on account of its solidity and blackness, as being most likely to give an impartial result, of the modifications arising from an illumination by differently-coloured rays; but, on viewing it, I was struck with the sight of a VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 670 bright constellation of thousands of luminous points, scattered over its whole extent, as far as the field of the microscope could take it in. Their light was that of the illuminating colour, but differed considerably in brightness; some of the points being dim and faint, while others were luminous and brilliant. The brightest of them also admitted of a little variation in their colour, or rather in the intensity of the same colour; for, in the centre of some of the most brilliant of these lucid appearances, their light had more vivacity, and seemed to deviate from the illuminating tint towards whiteness, while on and near the circumference it appeared to take a deeper hue. An object so well divided by nature, into very minute and differently-arranged points, on which the attention might be fixed, in order to ascertain whether they would be equally distinct in all colours, and whe- ther their number would be increased or diminished by different degrees of illumi- nation, was exactly what I wanted ; nor could I think it less remarkable, that all the other objects I had fixed on, besides many more which have been examined, such as copper, tin, silver, &c. presented themselves nearly with the same appear- ance. In the brass, which had been turned in a lathe, the luminous points were arranged in furrows; and in tin they were remarkably beautiful. The result of the examination of my objects was as follows. Exper. 2. Red paper. In the red rays, I view a bright point near an accidental black spot in the paper, which serves me as a mark; and I notice the space be- tween the point and the spot : it contains several faint points. In the orange rays, I see better. The bright point I now perceive is double. In the yellow rays, I see the object still better. In the green rays, full as well as before. In the blue rays, very well. In the indigo rays, not quite so well as in the blue. In the violet rays, very imperfectly. Exper. 3. Green paper. Red. I fix my attention on many faint points, in a space between 2 bright double points. Orange ; I see those faint points better. Yellow ; still better. Green ; as well as before : I see remarkably well. Blue ; less bright, but very distinct. Indigo; not well. Violet; bad. Exper. 4. A piece of very clean turned brass. r. I remark several faint luminous points between 1 bright ones. The colour of the brass makes the red rays appear like orange, o. I see better, but the orange colour is likewise different from what it ought to be ; however, this is not at present the object of my investigation, y. I see still better, g. I see full as well as before, b. I do not see so well now. i. I cannot see well. v. Bad. Exper. 5. A nail. r. I remark 1 bright points, and some faint ones. o. Brighter than before; and more points visible: very distinct, y. Much brighter than before; and more points and lines visible: very distinct, g. Full as bright: and as many points visible : very distinct, b. Much less bright ; very distinct, i. Still less bright : very distinct, v. Much less bright again : very distinct. Exper. 6. I viewed a guinea, at Q feet 6 inches from the prism ; and adjusted the place of the object in the several rays, by the shadow of the guinea : If this 680 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. be not done, deceptions will take place, r. 4 remarkable points : very distinct. o. Better illuminated : very distinct, y. Still better illuminated : very distinct : The points all over the field of view are coloured ; some green ; some red ; some yellow; and some white, encircled with black about them. Between yellow and green is the maximum of illumination. Extremely distinct, g. As well illumi- nated as the yellow : very distinct, b. Much inferior in illumination : very distinct. i. Badly illuminated : distinct, v. Very badly illuminated : I can hardly see the object at all. Exper. 7. The nail again, at 8 feet from the prism, r. I attended to 2 bright points, with faint ones between them almost all the points in the field of view are red : very distinct, o. I see all the points better : they are red, green, yellow, and whitish, with black about them : very distinct, y. I see better : more bright points, and more faint ones : the points are of various colours : very distinct, g. I see as well : the points are mostly green, and brightish-green, inclining to white: very distinct, b. Much worse illuminated : very distinct. 1. Badly illuminated: very distinct, v. There is hardly any illumination. Exper. 8. The nail again, at 9 feet 6 inches from the prism, by way of having the rays better separated, r. Badly illuminated : the bright points are very dis- tinct, o. Much better illuminated : the bright points very distinct, y. Still better illuminated : all points extremely distinct, g. As well illuminated, and equally distinct, b. Badly illuminated : the bright points are distinct ; but the others are not so. 1. Very badly illuminated : I do not see distinctly ; but I believe it to be for want of light, v. So badly illuminated that I cannot see the object ; or at least but barely perceive that it exists. Exper. 9. Black paper at 8 feet from the prism, r. The object is hardly visible: I can only see a few faint points, o. I see several bright points, and many faint ones. y. Numberless bright and small faint points. Between yellow and green, is the maximum of illumination, g. the same as the yellow, b. Very indiffer- ently illuminated ; but not so bad as in the red rays. 1. I cannot see the object. v. Totally invisible. From these observations, which agree uncommonly well, with respect to the illuminating power assigned to each colour, we may conclude, that the red-making rays are very far from having it in any eminent degree. The orange possess more of it than the red ; and the yellow rays illuminate objects still more perfectly. The maximum of illumination lies in the brightest yellow, or palest green. The green itself is nearly equally bright with the yellow; but, from the full deep green, the illuminating power decreases very sensibly. That of the blue is nearly on a par with that of the red; the indigo has much less than the blue; and the violet is very deficient. With regard to the principle of distinctness, there appears to be no deficiency in any one of the colours. In the violet rays, for instance, some of the experi- ments mention that I saw badly; but this is to be understood only with respect to VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 681 the number of small objects that could be perceived; for though I saw fewer of the points, those which remained visible were always as distinct as, in so feeble an illumination, could be expected. It must indeed be evident, that by removing the great obstacle to distinct vision, which is, the different refrangibility of the rays of light, a microscope will be capable of a much higher degree of distinctness than it can be under the usual circumstances. A celebrated optical writer has formerly remarked, that a fly, illuminated by red rays, appeared uncommonly distinct, and that all its minute parts might be seen in great perfection; and, from the experi- ments which have been related, it appears that every other colour is possessed of the same advantage. I am well aware that the results I have drawn from the foregoing experiments, both with regard to the heating and illuminating powers of differently-coloureJ rays, must be affected by some little inaccuracies. The prism, under the circum- stances in which I have used it, could not effect a complete separation of the colours on account of the apparent diameter of the sun, and the considerable breadth of the prism itself, through which the rays were transmitted. Perhaps an arrangement like that in fig. 16, of the Newtonian experiments, might be em- ployed; if instruments of sufficient sensibility, such as air thermometers, can be procured, that may be affected by the enfeebled illumination of rays that have undergone 4 transmissions, and 8 refractions; and especially when their incipient quantity has been so greatly reduced, in their limited passage through a small hole at the first incidence. But it appeared most expedient for me, at present, to neglect all further refine- ments, which may be attempted hereafter at leisure. It may even be presumed that, had there not been some small admixture of the red rays in the other colours, the result would have been still more decisive, with regard to the power of heating vested in the red rays. And it is also evident, that at least the red light of the prismatic spectrum, was much less adulterated than any of the other colours; their refractions tending all to throw them from the red. That the same rays which occasion the greatest heat, have not the power of illumination in any strong degree, stands on as good a foundation. For since here also they have undergone the fairest trial, as being most free from other colours, it is equally proved that they illuminate objects but imperfectly. There is some probability that a ray, purified in the Newtonian manner above quoted, especially in a well darkened room, may remain bright enough to serve the purpose of microscopic illumination, in which case more precision can easily be obtained. The greatest cause for a mixture of colours however, which is, the breadth of the prism, I saw might easily be re- moved; therefore, on account of the coloured points, which have been mentioned in the 6th and 7 th experiments, I was willing to try whether they proceeded from this mixture; and therefore covered the prism in front with a piece of pasteboard, having a slit in it of about TlT of an inch broad. Exper. 10. The nail, at 9 feet 2 inches from the prism, r. I fix my attention vol. xviii. 4 S 682 PHILOSOPHICAL TRANSACTIONS. [ANNO ] 800. on 2 shining, red points; they are pretty bright, o, I see many more points : the object is better illuminated than in the red: the points are surrounded by black; but are orange-coloured, y. The points now are yellow, and white surrounded by black : the object is better illuminated than in orange. The maximum of illumi- nation is in the brightest yellow, or palest green, g. The points are green and white, as before surrounded by black : better illuminated than in orange, b. The illumination is nearly equal to red. i. Very indifferently illuminated, v. Very badly illuminated. The phenomena of the differently-coloured points being now completely resolved, since they were plainly owing to the former admixture of colours, and the illumi- nating power remaining ascertained as before, I attempted also to repeat the experi- ments on the thermometer, with the prism covered in the same manner ; but I found the effect of the coloured rays too much enfeebled to give a decisive result. I might now proceed to my next subject; but it may be pardonable if I digress for a moment, and remark, that the foregoing researches ought to lead us on to others. May not the chemical properties of the prismatic colours be as different as those which relate to light and heat ? Adequate methods for an investigation of them may easily be found; and we cannot too minutely enter into an analysis of light, which is the most subtle of all the active principles that are concerned in the mechanism of the operations of nature. A better acquaintance with it may enable us to account for various facts that fall under our daily observation, but which have hitherto remained unexplained. If the power of heating, as we now see, be chiefly lodged in the red- making rays, it accounts for the comfortable warmth that is thrown out from a fire, when it is in the state of a red glow ; and for the heat which is given by charcoal, coke, and balls of small-coal mixed up with clay, used in hot-houses; all which, it is well known, throw out red light. It also explains the reason why the yellow, green, blue, and purple flames of burn- ing spirits mixed with salt, occasion so little heat that a hand is not materially injured, when passed through their coruscations. If the chemical properties of colours also, when ascertained, should be such that an acid principle, for instance, which has been ascribed to light in general, on account of its changing the com- plexion of various substances exposed to it, may reside only in one of the colours, while others may prove to be differently invested, it will follow, that bodies may be variously affected by light, according as they imbibe and retain, or transmit and reflect, the different colours of which it is composed. Radiant Heat is of Different Refrangibility. — I must now remark, that my foregoing experiments ascertain beyond a doubt, that radiant heat, as well as light, whether they be the same or different agents, is not only refrangible, but is also subject to the laws of the dispersion arising from its different refrangibility ; and, as this subject is new, I may be permitted to dwell a few moments on it. The prism refracts radiant heat, so as to separate that which is less efficacious, from that which is more so. The whole quantity of radiant heat, contained in a sun- VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 683 beam, if this different refrangibility did not exist, must inevitably fall uniformly on a space equal to the area of the prism ; and if radiant heat were not refrangible at all, it would fall on an equal space, in the place where the shadow of the prism, when covered, may be seen. But neither of these events taking place, it is evident that radiant heat is subject to the laws of refraction, and also to those of the dif- ferent refrangibility of light. May not this lead us to surmise, that radiant heat consists of particles of light of a certain range of momenta, and which range may extend a little farther, on each side of refrangibility, than that of light ? We have shown, that in a gradual exposure of the thermometer to the rays of the pris- matic spectrum, beginning from the violet, we come to the maximum of light, long before we come to that of heat, which lies at the other extreme. By several experiments, which time will not allow me now to report, it appears that the maxi- mum of illumination has little more than half the heat of the full red rays ; and, from other experiments, I likewise conclude, that the full red falls still short of the maximum of heat ; which perhaps lies even beyond visible refraction. In this case, radiant heat will at least partly, if not chiefly, consist, if I may be permitted the expression, of invisible light ; that is to say, of rays coming from the sun, that have such a momentum as to be unfit for vision. And admitting, as is highly probable, that the organs of sight are only adapted to receive impressions from particles of a certain momentum, it explains why the maximum of illumination should be in the middle of the refrangible rays ; as those which have greater or less momenta, are likely to become equally unfit for impressions of sight. Whereas, in radiant heat, there may be no such limitation to the momentum of its particles. From the powerful effects of a burning lens however we gather the information, that the momentum of terrestrial radiant heat is not likely to exceed that of the sun ; and that consequently the refrangibility of calorific rays cannot extend much beyond that of colourific light. Hence we may also infer, that the invisible heat of red-hot iron, gradually cooled till it ceases to shine, has the momentum of the invisible rays which, in the solar spectrum viewed by day-light, go to the confines of red; and this will afford an easy solution of the reflection of invisible heat by concave mirrors. Application of the Result of the foregoing Observations, to the Method of viewing the Sun advantageously, with Telescopes of large Apertures and high magnifying Powers. — Some time before the late transit of Mercury over the sun's disc, I pre- pared my 7-feet telescope, in order to see it to the best advantage. As I wished to keep the whole aperture of the mirror open, I soon cracked every one of the darkening slips of wedged glasses, which are generally used with achromatic tele- scopes : none of them could withstand the accumulated heat in the focus of pencils, where these glasses are generally placed. Being thus left without resource, I made use of red glasses ; but was by no means satisfied with their performance. My not being prepared, as it happened, was of no consequence; the weather proving totally unfavourable for viewing the sun at the time of the transit. 4s 2 684 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. However, as I was fully aware of the necessity of providing an apparatus for this purpose, since no method that was in use could be applied to my telescopes, I took the first opportunity of beginning my trials. The instrument I wished to adapt for solar inspection, was a Newtonian reflector, with 9 inches aperture ; and my aim was, to use the whole of it open. I began with a red glass, and, not finding it to stop light enough, took 2 of them together. These intercepted full as much light as was necessary ; but I soon found that the eye could not bear the irritation, from a sensation of heat, which it appeared these glasses did not stop. I now took 2 green glasses; but found that they did not intercept light enough. I therefore smoked one of them ; and it appeared that, notwithstanding they now still transmitted considerably more light than the red glasses, they remedied the former inconvenience of an irritation arising from heat. Repeating these trials several times, I constantly found the same result ; and, the sun in the first case being of a deep red colour, I surmised that the red-making rays, transmitted through red glasses, were more efficacious in raising a sensation of heat, than those which passed through green, and which caused the sun to look greenish. In consequence of this surmise, I undertook the investigations which have been delivered under the first 2 heads. As soon as I was convinced that the red light of the sun ought to be intercepted, on account of the heat it occasions, and that it might also be safely set aside, since it was now proved that pale green light excels in illumination, the method which ought to be pursued in the construction of a darkening apparatus was sufficiently pointed out ; and nothing remained but to find such materials as would give us the colour of the sun, viewed in a telescope, of a pale green light, sufficiently tempered for the eye to bear its lustre. To determine what glasses would most effectually stop the red rays, I procured some of all colours, and tried them in the following manner. I placed a prism in the upper part of a window, and received its coloured spectrum on a sheet of white paper. I then intercepted the colours just before they came to the paper, succes- sively, by the glasses, and found the result as follows. A deep red glass inter- cepted all the rays. A paler red did the same. From this, we ought not to con- clude that red glasses will stop the red rays ; but rather, that none of the sun's light, after its dispersion by the prism, remains intense enough to pass through red glasses, in sufficient quantity to be perceptible, when it comes to the paper. By looking through them directly at the sun, or even at day objects, it is sufficiently evident that they transmit chiefly red rays. An orange glass transmitted nearly all the red, the orange, and the yellow. It intercepted some of the green ; much of the blue ; and very little of the indigo and violet. A yellow glass intercepted hardly any light, of any one of the colours. A dark green glass intercepted nearly all the red, and partly also the orange and yellow. It transmitted the green ; intercepted much of the blue; but none of the indigo and violet. A darker green glass intercepted nearly all the red ; much of VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 685 the orange; and a little of the yellow. It transmitted the green; stopped some of the blue; but transmitted the indigo and violet. A blue glass intercepted much of the red and orange; some of the yellow; hardly any of the green; none of the blue, indigo, or violet. A purple glass transmitted some of the red; a very little of the orange and yellow: it also transmitted a little of the green and blue; but more of the indigo and violet. From these experiments we see, that dark green glasses are most efficacious for intercepting red light, and will therefore answer one of the intended purposes; but since, in viewing the sun, we have also its splendour to contend with, I pro- ceeded to the following additional trials. White glass, lightly smoked, apparently intercepted an equal share of all the colours; and when the smoke was laid on thicker, it permitted none of them to pass. Hard pitch, melted between 2 white glasses, intercepted much light; and, when put on sufficiently thick, transmitted none. Many differently coloured fluids, that were also tried, I found were not sufficiently pure to be used, when dense enough to stop light. Now, red glasses, and the 2 last-mentioned resources of smoke, and pitch, any one of which, it has been seen, will stop as much light as may be required, had still a remaining trial to undergo, relating to distinctness; but this I was convinced could only be decided by actual observations of the sun. As an easy way of smoking glasses uniformly is of some consequence to distinct vision, it may be of service here to give the proper directions, how to proceed in the operation. With a pair of warm pliers, take hold of the glass, and place it over a candle, at a sufficient distance not to contract smoke. When it is heated, but no more than still to permit a finger to touch the edges of it, bring down the glass, at the side of the flame, as low as the wick will permit, which must not be touched. Then, with a quick vibratory motion, agitate it in the flame from side to side; at the same time advancing and retiring it gently all the while. By this method, you may proceed to lay on smoke to any required darkness. It ought to be viewed from time to time, not only to see whether it be sufficiently dark, but whether any ine- quality may be perceived; for if that should happen, it will not be proper to go on. The smoke of sealing-wax is bad : that of pitch is worse. A wax candle gives a good smoke; but that of a tallow candle is better. As good as any I have hitherto met with, is the smoke of spermaceti oil. In using a lamp, you may also have the advantage of an even flame extended to any length. Telescopic experiments. — N° 1. To put my theory to the trial, I used 2 red glasses, and found that the heat which passed through them could not be suffered a moment; but I was now also convinced that distinctness of vision is capitally in- jured by the colouring matter of these glasses. N° 2. I smoked a white glass, till it stopped light enough to permit the eye to bear the sun. This destroyed all dis- tinctness; and also permitted some heat to come to the eye, by transmitting chiefly red rays. N° 3. I applied 2 white glasses, with pitch between them, to the tele- 686 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. scope; and found that it made the sun appear of a scarlet colour. They transmitted some heat; and distinctness was greatly injured. N° 4. I used a very dark green glass, to stop heat ; and behind it, or towards the eye, I placed a red glass, to stop light. The first glimpse I had of the sun, was accompanied with a sensation of heat; distinctness also was materially injured. N° 5. I used a dark green and a pale red; but, the sun not being sufficiently darkened, I smoked the red glass, and, putting a small partition between the two, placed the smoke towards the green glass. This took off the exuberance of light; but did not remedy the inconve- nience arising from heat. N° 6. I used 2 pale green glasses; smoking that next to the eye, and placing it as in N° 5, so that the smoke might be inclosed between the two. This acted in- comparably well; but, in a very short time, the heat which passed the first glass, (though not the second, for I felt no sensation "of it in the eye) disordered the smoke, by drawing it up into little blisters or stars, which let through light; and this composition therefore soon became useless. N°7- I used 2 dark green glasses, one of them smoked, as in N05. These also acted well; but became useless, for the reason assigned in N° 6, though somewhat less smoke had been required than in the former composition, I felt no heat. N° 8. I used one pale green, with a dark green smoked glass on it, as in N° 5. It bore an aperture of 4 inches very well, and the smoke was not disordered; but when all the tube was open, the pale green glass cracked in a few minutes. N° 9. Placing now a dark green before a smoked green, I saw the sun remarkably well. In this experiment, I had made a difference in the arrangement of the apparatus. The cracking of the glasses, I supposed might be owing to their receiving heat in the middle, while the outside remained cold; which would occasion a partial dilatation. I therefore cut them into pieces about a quarter of an inch square, and set 3 of them in a slider, so that I could move them behind the smoked glass, without disturbing it. After looking about 3 or 4 minutes through one of them, I moved the slider to the 2d, and then to the 3d. This kept the glasses sufficiently cool ; but the disturbance of the alte- rations proved hurtful to vision, which requires repose; and if perchance I stopped a little longer than the proper time, the glass cracked, with a very disagreeable ex- plosion, that endangered the eye. N° 10. Two dark green glasses, both smoked, that a thinner coat might be on each; but the smoke still contracted blisters, though less dense than before. N° 1 1 . To get rid of smoke entirely, I used 2 dark green glasses, 2 very dark green, 2 pale blue, and 1 pale green glass, together. Distinctness was wanting; nor was light sufficiently intercepted. N° 12. A dark green and a pale blue glass, smoked. The green glass cracked. N° 13. A pale blue and a dark green glass, smoked. The blue glass cracked. The eye felt no sensation of heat. N° 14. Two pale blue glasses, one smoked. The first glass cracked. It was now sufficiently evident, that no glass which stops heat, and therefore receives it, could be preserved from cracking, when exposed to the focus of pencils. VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 6§7 This induced me to try an application of the darkening apparatus to another part of the telescope. The place where the rays are least condensed, without inter- fering with the reflections of the mirrors, is immediately close to the small one. I therefore screwed an apparatus to the speculum arm, into which any glass might be placed. N° 15. A dark green glass close to the small speculum, and smoked pale green in the focus of pencils, as before. I saw remarkably well. N° l6\ The dark green as before; but, that more light might be admitted, a white smoked glass near the eye. Better than N° 15; but the green glass cracked. N° 17. A very dark green and white smoked glass, as before. Very distinct, but the green glass cracked in about 6 or 7 minutes. N° 18. A dark blue glass, as in N° 15, and white smoked. This was distinct; and no heat came to the eye. The sun appeared ruddy. N° 1 9. A dark blue and a yellow glass, close together, as in N° 15, and a white smoked one, as before. This was not distinct. N° 20. A purple glass, as in N° 15, with a white smoked one. This gave the sun of a deep orange colour, approaching to scarlet. It was not distinct. N° 21. An orange glass, as in N° 15, with a white smoked one. The colour of the sun was too red. N° 22. A white smoked glass, as in N° 15, without any other at the eye. This gave the sun of a beautiful orange colour, but distinctness was totally destroyed. N° 23. The heat near the small speculum being still too powerful for the glasses, I had a bluish dark green glass made of a proper diameter to be inclosed between the 2 eye-glasses of a double eye-piece. All glass I knew would stop some heat; and was therefore in hopes that the interposition of this eye-glass would temper the rays, so as in some measure to protect the coloured glass. In the usual place near the eye, I put 2 white glasses, with a thin coat of pitch between them. These glasses, when looked through by the natural eye, give the sun of a red colour; I therefore entertained no great hopes of their application to the telescope. They darkened the sun not sufficiently; and, when the pitch was thickened, distinctness was wanting. N° 24. The same glass between the eye-glasses, and a dark green smoked glass at the eye. Very distinct. This arrangement is preferable to that of N° 15; after some considerable time however this glass also cracked. N° 25. I placed a very dark green glass behind the 2d eye-glass, that it might be sheltered by both glasses, which in my double eye-piece are close together, and of an equal focal length. Here, as the rays are not much concentrated, the coloured glass receives them on a large surface, and stops light and heat, in the proportion of the squares of its diameter now used, to that on which the rays would have fallen, had it been placed in the focus of pencils. And, for the same reason, I now also placed a dark green smoked glass close on the former, with the smoked side to- wards the eye, that the smoke might also be protected against heat, by a passage of the rays through 2 surfaces of coloured glass. This position had also the ad- vantage of leaving the telescope, with its mirrors and glasses, completely to perform its operation, before the application of the darkening apparatus; and thus to pre- 688 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. vent the injury which must be occasioned, by the interposition of the heterogeneous colouring matter of the glasses and of the smoke. N° 26. I placed a deep blue glass with a bluish green smoked one on it, as in N° 25, and found the sun of a whiter colour than with the former composition. There was no disagreeable sensation of heat; though a little warmth might be felt. N° 27. I Uvsed 2 black glasses, placed as in N° 25. Here there was no occasion for smoke; but the sun appeared of a bright scarlet colour, and an intolerable Sen- sation of heat took place immediately. I rather suspect that these are very deep red glasses, though their outward appearance is black. In order to have a more sure criterion for heat, I applied Dr. Wilson's thermo- meter, N° 2, to the end of the eye-piece, where the eye is generally placed. With N° 25, it rose from 34 to 37 degrees. With N° 26, it rose from 35 to 46; and, with N° 27, it rose, very quickly, from 36 to 95 degrees. I am pretty sure it would have mounted up still higher; but, the scale extending only to 100, I was not willing to run the risk of breaking the thermometer by a longer exposure. It remains now only to be added, that with N° 25 and 26 I have seen uncommonly well ; and that, in a long series of very interesting observations on the sun, which will soon be communicated, the glasses have met with no accident. However, when the sun is at a considerable altitude, it will be advisable to lessen the aperture a little, in telescopes that have so much light as my 10-feet reflector; or, which will give us more distinctness, to view the sun earlier in the morning, and later in the afternoon; for, the light intercepted by the atmosphere in lower altitudes, will reduce its brilliancy much more uniformly than we can soften it, by laying more smoke on our darkening glasses. Now as few instruments in common use are so large as that to which this method of darkening has been adapted, we may hope that it will be of general utility in solar observations. XIV. Experiments on the Ref Tangibility of the Invisible Rays of the Sun. By JVm. Herschel, LL. D.t F. R. S. p. 284. In that section of my former paper which treats of radiant heat, it was hinted, though from imperfect experiments, that the range of its refrangibility is probably more extensive than that of the prismatic colours; but having lately had some favourable sun-shine, and obtained a sufficient confirmation of the same, it will be proper to add the following experiments to those which have been given. I pro- vided a small stand, with 4 short legs, and covered it with white paper. (See fig. 14, pi. 11). On this I drew 5 lines, parallel to one end of the stand, at half an inch distance from each other, but so that the first of the lines might only be 4- of an inch from the edge. These lines I intersected at right angles with 3 others; the 2d and 3d of which were respectively at 2^- and at 4 inches from the first. The same thermometers that have before been marked N° J, 2, and 3, mounted on their small inclined planes, were then placed so as to have the centres of the VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 6*89 shadow of their balls thrown on the intersection of these lines. Now, setting my little stand on a table, I caused the prismatic spectrum to fail with its extreme co- lour on the edge of the paper, so that none might advance beyond the first line. In this arrangement, all the spectrum, except the vanishing last quarter of an inch, which served as a direction, passed down by the edge of the stand, and could not interfere with the experiments. I had also now used the precaution of darkening the window in which the prism was placed, by fixing up a thick dark green curtain, to keep out as much light as convenient. The thermometers being perfectly settled at the temperature of the room, I placed the stand so that part of the red colour, refracted by the prism, fell on the edge of the paper, before the thermometer N° 1, and about half way, or l| inch, towards the 2d : it consequently did not come before that, or the 3d thermometer, both which were to be my standards. During the experiment, I kept the last ter- mination of visible red carefully to the first line, as a limit assigned to it, by gently moving the stand when required; and found the ther- mometers, which were all placed on the 2d line, af- fected as annexed. Here the thermometer N° 1 rose 6*4- degrees, in 10 minutes, when its centre was placed 4. inch beyond visible light. In order to have a confirmation of this fact, I cooled the thermometer N° 1, and placed N° 2 in the room of it: I also put N° 3 in the place of N°2, and N° 1 in that of N° 3 ; and having exposed them as before arranged on the 2d line, I had the annexed result. Here the thermometer N° 2 rose to 2£ degrees, in 1 2 minutes; and being much more sensible than N° J, it came to the temperature of its situation in a short time; but I left it exposed longer, on purpose to be perfectly assured of the result. Its showing but 2$ degrees advance, when N° 1 showed 6±y has also been accounted for before. It being now evident that there was a refraction of rays coining from the sun, which, though not fit for vision, were yet highly invested with a power of occa- sioning heat, I proceeded to examine its extent as follows. The thermometers were arranged on the 3d 46 *' 46 2' 45a ' line, instead of the 2d; and the stand was, as before, 50 4,6% 46 s°l. N°2. N°3. 45 45 44 49 45 44 51 44| 44 50| 43 j «i N°2. N°3. N°l. 44 44 45 47 44 45 46f 44 45 46* 44 45 N° 1. N°2. 46 46 50 4>6\ 51| 46| 52i 47 immersed up to the first, in the coloured margin of the *if J£* *5| vanishing red rays. The result was thus. Here the thermometer N° 1 rose 5£ degrees, in 1 3 minutes, at 1 inch behind the visible light of the red rays. I now placed the thermometers on the 4th line, in- stead of the 3d ; and, proceeding as before, I had the annexed result. Therefore the thermometer N° 1 rose 3-f degrees, in 10 minutes, at H inch beyond the visible light of the red rays. vol. xviii, 4 T N° 1. N9 2. N° 3 48£ 48£ 47| »lj 48| 47| N°l. N°2. N°3. 48 48 47| 48 48 47| 48 4T| 47 48£ 47| 47 48 48 47| N°l. N°2. N°3. 48 48 47| 48* 48 47| 48§ 48J 47£ 49 48 J 47| 6qo philosophical transactions. [anno 1800. I might now have gone on to the 5th line; but, so fine a day, with regard to clearness of sky and perfect calmness, was not to be expected often, at this time of the year; I therefore hastened to make a trial of the other extreme of the prismatic spectrum. This was attended with some difficulty, as the illumination of the violet rays is so feeble, that a precise termination of it cannot be perceived. However, as well as could be judged, I placed the thermometers 1 inch beyond the reach of the violet rays, and found the result as annexed. Here the several indications of the thermometers, 2 of which, Nc 1 and 2, were used as variable, while the 3d was kept as the standard, were read off during a time that lasted 12 minutes; but they afford, as may be seen by inspection, no ground for ascribing any of their small changes to other causes than the accidental disturbance which will arise from the motion of the air, in a room where some employment is carried on. I now exposed the thermometer to the line of the very first perceptible violet light; but so that N° 1 and 2 might again be in the illumination, while N° 3 remained a standard. The result proved as annexed. Here the thermometer N° 1 rose 1° in 15 minutes; and N° 2 rose 4-°, in the same time. From these last experiments, I was now suffici- ently persuaded, that no rays which might fall beyond the violet, could have any perceptible power, either of illuminating or of heating; and that both these powers continued together throughout the prismatic spectrum, and ended where the faintest violet vanishes. A very material point remained still to be determined, which was, the situation of the maximum of the heating power. As I knew already that it did not lie on the violet side of the red, I began at the full red colour, and exposed my thermo- meters, arranged on a line, so as to have the ball of N° 1 in the midst of its rays, while the other 2 remained at the side, unaffected by N° l. N°2. N°3. them. Here the thermometer N° 1 rose 7° in 10 mi- *?* 4**f 48 oo$ 48§ 48 nutes, by an exposure to the full red coloured rays. 55J 4s| 48 I drew back the stand, till the centre of the ball of N° 1 was just at the vanishing of the red colour, so that half of its ball was within, N° l. N° 2. N°3. and half without, the visible rays of the sun. Here Jgl *ff f J _ . • 8 4oj 48 the thermometer N 1 rose 8° in 10 minutes. 57 49 48^ By way of not losing time, in order to connect these last observations the better together, I did not bring back the thermometer N° 1 to the temperature of the room, being already well acquainted with its rate of showing, compared to that of N° 2, but went on to the next experiment, by withdrawing the stand, till the whole ball of N° 1 was completely out of the sun's visible rays, yet so as to bring the termination of the N°l. N°2. N°3. 57 49 48$ 58$ 491 49 59 50| 492 59 50 49i N° 1. N°2. N°3. 50£ 57| 58 \ 58f 5Q£ 50 50 50 50 491 491 4>9h e sun. Now, as before VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 6QI line of the red colour as near the outside of the ball as could be, without touching it. Here the thermometer N° 1 rose, in 10 minutes, another degree higher than in its former situation it could be brought up to ; and was now 9° above the standard. The ball of this thermometer is exactly half an inch in diameter; and its centre therefore was -£- inch beyond the visible illumination, to which no part of it was exposed. It would not have been proper to compare these last observations with those taken at an earlier period this morning, in order to obtain a true maximum, as the sun was now more powerful than it had been at that time: for which reason, I caused the line of termina- tion of visible light, now to fall again just 4- inch from the centre of the ball; and had the annexed result. And here the thermometer N° 1 rose, in 10* minutes, 84-°, when its centre was 4- inch out of the visible rays of the sun. we had a rising of 9°, and here 8^, the difference is almost too trifling to suppose, that this latter situation of the thermometer was much beyond the maximum of the heating power; while at the same time the experiment sufficiently indicates, that the place inquired after need not be looked for at a greater distance. It will now be easy to draw the result of these observations into a very narrow compass. The first 4 experiments prove, that there are rays coming from the sun, which are less refrangible than any of those that affect the sight. They are invested with a high power of heating bodies, but with none of illuminating objects; and this explains the reason why they have hitherto escaped unnoticed. My present intention is, not to assign the angle of the least refrangibility belonging to these rays, for which purpose more accurate, repeated, and extended experiments are required. But, at the distance of 52 inches from the prism, there was still a con- siderable heating power exerted by our invisible rays, 1± inch beyond the red ones, measured on their projection on a horizontal plane. I have no doubt but that their efficacy may be traced still somewhat farther. The 5th and 6th experiments show, that the power of heating is extended to the utmost limits of the visible violet rays, but not beyond them; and that it is gradually impaired, as the rays get more refran- gible. The last 4 experiments prove, that the maximum of the heating power is vested among the invisible rays; and is probably npt less than half an inch beyond the last visible ones, when projected in the manner before mentioned. The same experiments also show, that the sun's invisible rays, in their less refrangible state, and considerably beyond the maximum, still exert a heating power fully equal to that of red-coloured light ; and that consequently, if we may infer the quantity of the efficient from the effect produced, the invisible rays of the sun probably far exceed the visible ones in number. To conclude, if we call light, those rays which illuminate objects, and radiant heat, those which heat bodies, it may be inquired, whether light be essentially dif- ferent from radiant heat? In answer to which I would suggest, that we are not 4 T 2 6q'1 philosophical transactions. [anno 1800. allowed, by the rules of philosophizing, to admit 1 different causes to explain cer- tain effects, if they may be accounted for by 1 . A beam of radiant heat, ema- nating from the sun, consists of rays that are differently refrangible. The range of their extent, when dispersed by a prism, begins at violet-coloured light, where they are most refracted, and they have the least efficacy. We have traced these calorific rays throughout the whole extent of the prismatic spectrum ; and found their power increasing, while their refrangibility was lessened, as far as to the con- fines of red-coloured light. But their diminishing refrangibility, and increasing power, did not stop here; for we have pursued them a considerable way beyond the prismatic spectrum, into an invisible state, still exerting their increasing energy, with a decrease of refrangibility up to the maximum of their power; and have also traced them to that state where, though still less refracted, their energy, on ac- count, we may suppose, of their now failing density, decreased pretty fast; after which, the invisible thermometrical spectrum, if I may so call it, soon vanished. If this be a true account of solar heat, for the support of which I appeal to my experiments, it remains only for us to admit, that such of the rays of the sun as have the refrangibility of those which are contained in the prismatic spectrum, by the construction of the organs of sight, are admitted, under the appearance of light and colours; and that the rest, being stopped in the coats and humours of the eye, act on them, as they are known to do on all the other parts of our body, by occasioning a sensation of heat. In the view of the apparatus, fig. 14, pi. 11, ab is the small stand; 1, 2, 3, the thermometers on it j cd the prism at the window; e the spectrum thrown on the table, so as to bring the last quarter of an inch of the red colour on the stand. XV. Experiments on the Solar, and on the Terrestrial Rays that occasion Heat ; with a Comparative View of the Laws to which Light and Heat, or rather the Rays which occasion them, are subject, in order to determine whether they are the same, or different. By Wm. Herschel, LL.D., F.R.S. p. 293. The word heat, in its common acceptation, denotes a certain sensation well- known to every person. The cause of this sensation, to avoid ambiguity, ought to have been distinguished by a name different from that which is used to point out its effect. Various authors indeed, who have treated on the subject of heat, have occasionally added certain terms to distinguish their conceptions, such as, latent, absolute, specific, sensible heat ; while others have adopted the new expressions of caloric, and the matter of heat. None of these descriptive appellations however would have completely answered my purpose. I might, as in the preceding papers, have used the name radiant heat, which has been introduced by a celebrated author, and which certainly is not very different from the expressions I have now adopted; but, by calling the subject of my researches, the rays that occasion heat, I cannot be misunderstood as meaning that these rays themselves are heat; nor do I in any respect engage myself to show in what manner they produce heat. VOLXC.] PHILOSOPHICAL TRANSACTIONS. 6Q3 From what has been said it follows, that any objections that may be alleged, from the supposed agency of heat in other circumstances than in its state of radiance, or heat-making rays, cannot be admitted against my experiments. For, notwithstand- ing I may be inclined to believe that all phenomena in which heat is concerned, such as the expansion of bodies, fluidity, congelation, fermentation, friction, &c. as well as heat in its various states of being latent, specific, absolute, or sensible, may be explained on the principle of heat-making rays, and vibrations occasioned by them in the parts of bodies ; yet this is not intended, at present, to be any part of what I shall endeavour to establish. I must also remark, that in using the word rays, I do not mean to oppose, much less to countenance, the opinion of those philosophers who still believe that light itself comes to us from the sun, not by rays, but by the supposed vibrations of an elastic ether, every where diffused throughout space ; I only claim the same privilege for the rays that occasion heat, which they are willing to allow to those that illuminate objects. For, in what manner soever this radiance may be effected, it will be fully proved hereafter that the evidence, either for rays, or for vibrations which occasion heat, stands on the same founda- tion on which the radiance of the illuminating principle, light, is built. In order to enter on our subject with some regularity, it will be necessary to distinguish heat into 6 different kinds, 3 solar, and 3 terrestrial ; but, as the di- visions of terrestrial heat strictly resemble those of solar, it will not be necessary to treat of them separately ; our subject therefore may be reduced to the 3 following general heads. We shall begin with the heat of luminous bodies in general, such as, in the first place, we have it directly from the sun ; and as, in the 2d, we may obtain it from terrestrial flames, such as torches, candles, lamps, blue-lights, &c. Our next division comprehends the heat of coloured radiants. This we obtain, in the first place, from the sun, by separating its rays in a prism ; and, in the 2d, by having recourse to culinary fires, openly exposed. The 3d division relates to heat obtained from radiants, where neither light nor colour in the rays can be perceived. This, as I have shown, is to be had, in the first place, directly from the sun, by means of a prism applied to its rays ; and, in the 2d, we may have it from fires in- closed in stoves, and from red-hot iron cooled till it can no longer be seen in the dark. Besides the arrangement in the order of my experiments which would arise from this division, we have another subject to consider. For, since the chief design of this paper is to give a comparative view of the operations that may be performed on the rays that occasion heat, and of those which we already know to have been effected on the rays that occasion light, it will be necessary to take a short review of the latter. I shall merely select such facts as not only are perfectly well known, but especially such as will answer the intention of my comparative view, and arrange them in the following order. 1 . Light, both solar and terrestrial, is a sensation occasioned by rays emanating from luminous bodies, which have a power of illumi- nating objects; and, according to circumstances, of making them appear of various colours. 2. These rays are subject to the laws of reflection. 3. They are also Bubject to the laws of refraction. 4. They are of different refrangibility. 5. They <5g4 PHILOSOPHICAL TRANSACTIONS. [anno 1800, are liable to be stopped, in certain proportions, when transmitted through diapha- nous bodies. 6. They are liable to be scattered on rough surfaces. 7. They have hitherto been supposed to have a power of heating bodies ; but this remains to be examined. The similar propositions relating to heat, which are intended to be proved in this paper, will stand as follows. 1. Heat, both solar and terrestrial, is a sensation oc- casioned by rays emanating from candent substances, which have a power of heating bodies. 2. These rays are subject to the laws of reflection. 3. They are also sub- ject to the laws of refraction. 4. They are of different refrangibility. 5. They are liable to be stopped, in certain proportions, when transmitted through diaphanous bodies. 6. They are liable to be scattered on rough surfaces. 7. They may be supposed, when in a certain state of energy, to have a power of illuminating objects ; but this remains to be examined. I have to mention, that the number of experiments which will be required to make good all these points, exceeds the usual length of my papers ; on which ac- count, I shall divide the present one into 2 parts. Proceeding therefore now to an investigation of the first 3 heads that have been proposed, I reserve the next 3, and a discussion which will be brought on by the 7th article, for the 2d part. Exper. 1 . Reflection of the Heat of the Sun. — I exposed the thermometer, which in a former paper has been denoted by N° 3, to the eye-end of a J 0-feet Newtonian telescope, which carried a camera-eye-piece, but no eye-glass. When, by proper adjustment, the focus came to the ball of the thermometer, it rose from 52 to 110°; so that rays which came from the sun, underwent 3 regular reflections ; one, on a concave mirror, and the other 2, on 2 plain ones. Now these rays, whether they were those of light or not, for that our experiment cannot ascertain, had a power of occasioning heat, which was manifested in raising the thermometer 58°. Exper. 2. Refection of the Heat of a Candle. — At the distance of 29 inches from a candle, I planted a small steel-mirror, of 3-^ inches diameter, and about 24- inches focal length. (See pi. 12, fig, l). In the secondary focus of it, I placed the ball of the thermometer which in my paper has been marked N° 2 ; and very near it, but out of the reach of reflection, the thermometer N° 3. Having covered the mirror till both were come to the temperature of their stations, I began as annexed. Here, in 5 minutes, the ther- mometer N° 2 received 34- degrees of heat from the candle, by reflected rays. I now covered the mirror, but left all the rest of the apparatus untouched. — Here, in 6 minutes the thermometer lost the 3^- degrees of heat again, which it had gained before. I uncovered the mirror once more ; and, in 5 mi- nutes, the 34- degrees of heat were regained. In consequence of which, we are assured that certain N°2. N°3. Min. In the Focus. Standard. 0 54 54 1 55 54 2 56 54 3 57 54 4 57h 54 5 57\ 54 N°2. N°3. Min. In the Focus. Standard. 0 574 54 1 55\ 54 H 55 54 6 54, 54 om 54 54 n 56 54 3] 57 54 5 574 54 VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 6Q5 rays came from the candle, subject to the laws of reflection, which, though they might not be the rays of light, for that our experiment does not determine, were evidently invested with a power of heating the thermometer placed in the focus of the mirror. Exper. 3. Reflection of the Heat that accompanies the Solar Prismatic Colours. — In the spectrum of the sun, given by a prism, I placed my small steel mirror, with a thermometer in its focus, fig. 2, pi. 12. It was covered by a piece of pasteboard, which, through a proper opening, admitted all the visible colours to fall on its polished surface, but excluded every other ray of heat that might be, either on the violet or on the red side, beyond the spectrum. Then, placing the apparatus so as to have the thermometer in the red rays, but keeping the mirror covered up till the thermometer became settled, I 0 ' 58 * found it stationary at 58°. Uncovering the mirror, I had 2 93 as annexed. Here, in 2 minutes, the thermometer rose 35°, by reflected heat. I covered the mirror again, and in a few minutes the thermometer, exposed to the direct prismatic red, came down to 58° again. And thus the prismatic colours, if they are not themselves the heat-making rays, are at least accompanied by such as have a power of occasioning heat, and are liable to be regularly reflected. Exper. 4. Reflection of the Heat of a red-hot Poker. — I placed the small steel mirror at 12 inches from a red-hot poker, set with its heated end upwards, in a perpendicular position, and so elevated as to throw its rays Min N» 2 on the mirror, fig. 1, pi. 12. The thermometer N° 2 was o^ 54£ placed in its secondary focus, and had a small pasteboard ij 93 screen, to guard its ball from the direct heat of the poker. — I covered the mirror. Here, in 14- minute, the thermometer rose 38-±- degrees, by reflected rays; and when the mirror was covered up it fell in the next 14- minute, 28 degrees. On which account, we cannot but allow, that certain rays, whether those that shine or not, issue from an ignited poker, which are subject to the re- gular laws of reflection, and have a power of heating bodies. Exper. 5. Reflection of the Heat of a Coal Fire by a plain Mirror. — I placed a small speculum, such as I use with my 7-feet reflectors, on a stand, and so as to make an angle of 45 degrees with the front of it, fig. 3, pi. 12. This was after- wards to face the fire in my parlour chimney, and would make the same angle with the bars of the grate. At a distance of 3^ inches from the speculum, on the re- flecting side of it, was placed the thermometer N° 1 ; and close by it, but out of the reach of the reflected rays, the thermometer N° 4. The whole was guarded in front, against the influence of the fire, by an oaken board 14- inch thick, which had a circular opening of 1 4- inch diameter, opposite the situation of the plain mirror, to permit the fire to shine on it. The thermometers were divided from the mirror by a wooden partition, which also had an opening in it, that the reflected rays might come from the mirror to N° 1, while N° 4 remained screened from their influence. On exposing this ap- paratus to the fire, I had the annexed result. Here, in Min. N°l. N°4. 0 60 60 1 62 60 2 64 60 3 66 60 4 66 60 5 67 60k Min. N° 1. N°4. 0 62£ 6*1 1 63 62$ 2 64 63 4 64>h 63 i 65 63| 8 65$ 63k 10 66$ 63j 11 67 64* 696 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. 5 minutes, the heat reflected from the plain mirror raised the thermometer N° 1, 7° ; while the change in the temperature of the screened place, indicated by N° 4, amounted only to half a degree : which shows, that an open fire sends out rays that are subject to the laws of reflection, and occasion heat. Exper. 6. Reflection of Fire-heat by a Prism. — Every thing remaining arranged as in the 5th experiment, I removed the small plain mirror, and placed in its stead a prism, which had one of its angles of 90 degrees, and the other 2 of 45° each, fig. 3, pi. 12. It was put so as to have one of the sides facing the fire, while the other was turned towards the thermometer : the hypotenuse con- sequently made an angle of 45° with the bars of the grate. The apparatus, after having been cooled some time, was exposed to the fire, and the annexed result was taken. Here, in 1 lm, the rays reflected by the prism raised the thermometer 44 degrees ; but, the temperature of the place having undergone an alteration of 1-f- degrees, we can only place 2|- to the account of reflection. The apparatus be- coming now very hot, it would not have been fair to have continued the experi- ment for a longer time ; but the effect already produced was fully sufficient to show that even a prism, which stops a great many heat-making rays, still reflects enough of them to prove, that an open fire not only sends them out, but that they are sub- ject to every law of reflection. Exper. 7. Reflection of Invisible Solar Heat. — On a board of about 4 feet 6 inches long, I placed at one end, a small plain mirror, and at the other, 2 ther- mometers, fig. 4, pi. 12. The distance of N° 1, from the face of the mirror, was 3 feet 94 inches ; and N° 2 was put at the side of it, facing the same way, but out of the reach of the rays that were to be reflected by the mirror. The colours of the prism were thrown on a sheet of paper having parallel lines drawn on it, at half an inch from each other. The mirror was stationed on the paper; and was ad- justed in such a manner as to present its polished surface, in an angle of 45 degrees, to the incident coloured rays, by which means, they would be reflected towards the ball of the thermometer N° 1. In this arrangement, the whole apparatus might be withdrawn from the colours to any required distance, by attending to the last visible red colour, as it showed itself on the lines of the paper. When the thermometers were properly settled to the temperature of their situation, during which time the mirror had been covered, the apparatus was drawn gently away from the colours, so far as to cause the mirror, which was now open, to receive only the invisible rays of heat which lie beyond the confines of red. The re- sult was as annexed. Here, in 10m, the thermometer N° 1 received 4° of heat, reflected to it, in the strictest optical manner, by the plain mirror of a Newtonian telescope. The great regularity with which these in- visible rays obeyed the law of reflection, was such, that Dr. Wilson's sensible ther- • Min. N° 1. N°2. 0 56 56 — 57 56 — 59 56 7 60 56 10 60 56 VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 697 mometer N° 2, which had been chosen on purpose for a standard, and was within an inch of the other thermometer, remained all the time without the least indica- tion of any change of temperature that might have Min# No x No 2> arisen from straggling rays, had there been any such. I o 60 56 now took away the mirror, but left every thing else in 8 57 5g the situation it was. The effect of this was thus. Here, 10 56 56 in 10m, the thermometer N° 1 lost again the 4° it had acquired, while N° 2 still remained unaltered; and this becomes therefore a most decisive experiment, in proof of the existence of invisible rays, of their being subject to the laws of reflec- tion, and of their power of occasioning heat. Exper. 8. Reflection and Condensation of the Invisible Solar Rays. — I made an apparatus for placing the small steel mirror at any required angle, fig. 2, pi. 12 ; and having exposed it to the prismatic spectrum, so as to receive it perpendicularly, 1 caused the colours to fall on one half of the mirror, which, being covered by a semi- circular piece of pasteboard, would stop all visible rays, so that none of them could reach the polished surface. On the pasteboard were drawn several lines, parallel to the diameter, and at the distance of -^ of an inch from each other ; that, by with- drawing the apparatus, I might have it at option to remove the last visible red to any required distance from the reflecting surface. In the focus of the mirror was placed the thermometer N° 2. I covered now also the other half of the mirror, till the thermometer had assumed the temperature of its situation. Then, withdrawing the apparatus out of the visible spectrum, till the last No 2 tinge of red was -^ of an inch removed from the edge _ In the Focus of invisible of the pasteboard, and the whole of the coloured image 0 " 6l ' thus thrown on the semicircular cover, I opened the other 1 80 half of the mirror, for the admission of invisible rays. 2" 72 The result was as annexed. Here, in 1 minute the 4 ^4 thermometer rose 19 degrees. I covered the mirror. Here, in 3 minutes, the thermometer fell l6°. I opened In ^ Ffc°us2,of invisible the mirror again. Here, in 2 minutes, the thermo- Min. Heat, meter rose 24°. I covered the mirror once more. g g8 And, in 1 minute, the thermometer fell 190. Now by 7m qq this alternate rising and falling of the thermometer, 3 points are clearly ascertained. The first is, that there are invisible rays of the sun. The 2d, that these rays are not only reflexible, in the manner which has been proved in the foregoing experiment, but that, by the strict laws of reflection, they are capable of being condensed. And, in the 3d place, that by condensation, their heating power is proportionally increased ; for, under the circumstances of the ex- periment, we find that it extended so far as to be able to raise the thermometer, in 2 minutes, no less than 24°. Exper. 9. Reflection of Invisible Culinary Heat. — I planted my little steel mirror on a small board, fig. 5, pi. 12 ; and at a proper distance opposite to it I erected a vol. xviii. 4 U 698 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. slip of deal, £ inch thick, and 1 inch broad, in a horizontal direction, so as to be ot an equal height, in the middle of its thickness, with the centre of the mirror. Against the side, facing the mirror, were fixed the 2 thermometers N° 2 and N° 3, with their balls within half an inch of each other, and the scales turned the op- posite way. A little of the wood was cut out of the slip, to make room for the balls to be freely exposed. That of N° 2 was in the axis of the mirror ; and the ball of N° 3 was screened from the reflected rays, by a small piece of pasteboard tied to the scale. The small ivory scales of the thermometers, with the slip of wood at their back, which however was feather-edged towards the stove, intercepted some heat; but it will be seen presently that there was enough N<> N<> 3 to spare. When the Stove was of a good heat, I brought Min. In the Focus. Screened. the apparatus to a place ready prepared for it. Here we ° & ^ find that, in 1 minute, the invisible culinary heat raised the thermometer N° 2, 39 degrees ; while N° 3, from change of temperature, rose only 1 , though its exposure to the stove was in every respect equal to that of N° 3, except so far as relates to the rays returned by the mirror; and therefore the radiant nature of these invisible rays, their power of heating bodies, and their being subject to the laws of reflection, are equally established by this experiment. Exper. 10. Reflection of the Invisible Rays of Heat of a Poker, cooled from being red-hot till it could no longer be seen in a dark Place. — The great abundance of heat in the last experiment, would not allow of its being carried on without injury to the thermometer, the scale of which is not extensive ; I therefore placed a poker, when of a proper black heat, at 12 inches from the steel Min N 2 mirror, fig. 1, and received the effect of its condensed Mirror covered 0 ' 61' rays on the thermometer N° 2, placed in the focus. Open 1 68 * , , . , • .i • Covered 2 6l Then, alternately covering and uncovering the mirror, 0pen 3 ^ 1 minute at a time, the effect was thus. Here, in 6m, Covered 4 59 we have a repeated result of alternate elevations and de- covered '. '. ". *. *. 6 58 pressions of the thermometer, all of which confirm the reflexibility, the radiant nature, and the heating power, of the invisible rays that came from the poker. From these experiments it is now sufficiently evident, that in every supposed case of solar and terrestrial heat, we have traced out rays that are subject to the re- gular laws of reflection, and are invested with a power of heating bodies ; and this independent of light. For though, in 4 cases out of 6, we had illuminating as well as heating rays, it is to be noticed that our proof goes only to the power of occasioning heat, which has been strictly ascertained by the thermometer. If it should be said, that the power of illuminating objects, of these same rays, is as strictly proved by the same experiments, I must remark, that from the cases of in- visible rays brought forward in the last 4 experiments, it is evident that the con- clusion, that rays must have illuminating power, because they have a power of oc- casioning heat, is erroneous; and, as this must be admitted, we have a right to ask VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 699 for some proof of the assertion, that rays which occasion heat can ever become visible. But as we shall have an opportunity to say more of this hereafter, I pro- ceed now to investigate the refraction of heat-making rays. Exper. 1 1. Refraction of Solar Heat. — With a new 10-feet Newtonian telescope* the mirror of which is 24 inches in diameter of polished surface, I received the rays of the sun ; and, making them pass through a day-piece with 4 lenses, I caused them to fall on the ball of the thermometer N° 3, placed in their focus. Those who are acquainted with the lines in which the principal rays and pencils move through a set of glasses, will easily conceive how artfully, in our present instance, heat was sent from one place to another. Heat crossing heat, through many in- tersecting courses, without jostling together, and each parcel arriving at last safely to its destined place. As soon as the rays were brought to the thermometer, it rose almost instantly from 6o° to 130; and, being afraid of cracking the glasses, I turned away the telescope. Here the rays, which occasioned no less than 70 degrees of heat, had undergone 8 regular successive refractions ; so that their being subject to its laws cannot be doubted. Exper. 12. Refraction of the Heat of a Candle. — I placed a lens of about 1.4 inch focus, and 1.1 diameter, mounted on a small support, at a distance of 2.8 inches from a candle, fig. 6, and the thermometer N° 2, behind the lens, at an equal distance of about 2.8 inches ; but which ought to be very carefully adjusted to the secondary focus of the candle. Not far from the lens, towards the candle, was a pasteboard screen, with an aperture of nearly the same size as the lens. The sup- port of the lens had an eccentric pivot, on which it might be turned away from its place, and returned to the same situation again, at pleasure. This arrangement being made, the thermometer was for a few moments exposed to the rays of the candle, till it had assumed the temperature of its situation. Then the lens was turned on its pivot, so as to intercept the direct rays, which passed through the opening in the pasteboard screen, and to refract them to the focus, in which the thermometer was situated. Here, in 3ra, the thermo- meter received 2-l degrees of heat, by the refraction of the lens. The lens was now turned away. Here, in 3m, the thermometer lost 2-f degrees of heat. The lens was now returned to its situa- tion. And, in 3m, the thermometer regained the 2-f degrees of heat. A greater effect may be obtained by a different arrange- ment of the distances. Thus, if the lens be placed at 34- inches from a wax-candle, and the thermometer situated, as before, in the secondary focus, we shall be able to draw from 5 to 8 degrees of heat, according to the burning of the candle, and the accuracy of the adjustment of the thermometer to the focus. The experiment we have related shows evidently, that rays invested with a power of heating bodies, issue from a candle, and are subject to laws of refraction, nearly the same with those respecting light. 4u2 Min. N°2. 0 53i 1 55| 2 " 55| 3 56 Om 56 1 54| 2 54} 3 53* Qm 53^ 1 54| 2 55* 3 56 700 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. Exper. 13. Refraction of the Heat that accompanies the Coloured part of the Prismatic Spectrum. — I covered a burning lens of Mr. Dollond's, which is nearly Q inches in diameter, and very highly polished, with a piece of pasteboard, in which there was an opening of a sufficient size to admit all the coloured part of the prismatic spectrum, fig. 7. In the focus of the glass was placed the ther- mometer N° 3 ; and, when every thing was arranged properly, I covered the lens for 5 minutes, that the thermometer might Lens covered 0 64, assume the temperature of its situation. The result was °Pen l 176 as annexed. Here, in 1 minute, the thermometer received 1 1 2 degrees of heat, which came with the coloured part of the solar spectrum, and were refracted to a focus; so that, if the coloured rays themselves are not of a heat-making nature, they are at least accompanied with rays that have a power of heating bodies, and are subject to certain laws of refraction, which cannot differ much from those affecting light. Exper. 14. Refraction of the Heat of a Chimney Fire. — I placed Mr. Dollond's lens before the clear fire of a large grate, fig. 8. Its distance from the bars of the grate was 3 feet; and, in the secondary focus of it was placed the thermometer N° 1 . N° 4 was stationed, by way of standard, at 84 inches from the former, and at an equal distance from the fire. Before the thermometers was a slip of mahogany, which had 3 holes in it, -^ of an inch in diameter each. Behind the centre of the 1st hole, -§- of an inch from the back, was placed the thermometer N° 1 ; and between the 2d and 3d hole, guarded from the direct rays of the fire by the par- tition, at the same distance from the back, was put N° 4. Things being thus arranged, the situation of the ap- paratus which carried the thermometers, and that where the lens was fixed, were marked. Then the thermome- ters, having been taken away to be cooled, were re- stored to their places again, and their progress marked as annexed. Here, in 9% the rays coming from the fire, through the burning glass, gave 9f degrees of heat more to the thermometer N° 1, than N° 4, from change of temperature, had received behind the screen. Now to determine whether this was owing merely to a transmission of heat through the glass, or to a condensation of the rays, by the re- fraction of the burning lens, I took away the lens, as soon as the last observation of the thermometers was written down, and continued to take down their progress as thus. Here the direct rays of the fire, we see, could not keep up the thermometer N° 1 ; which lost 2^- degrees of heat, though the lens intercepted no longer any of them. I now restored the burning glass, and continued. Here again, the lens acted as a condenser of heat, and gave 14 degrees of it to the thermometer N° 1. I now once more took away the lens, and continued the experiment. N° 1. K°4. In. Burning Lens. Screened. 0 58 58 l* 65 60 3 68 61 5 70 tflj 7 7\l 6l| 9 71* 6l| Min. K° 1. N°4. 9* 71* 6if 11 70* 61* 12 70£ 6l| — 69* 6l| 14* 691 61% 15™ 69k 6i$ 16 69k 6ii 17 70 6i| 20 70| 6\i 25 71 6l| 25*' 71 «.'!.; 31 68 6ii VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 701 This again confirms the same, by loss of 3° of N° 1. N*4. , ° , . . 111 Min. Burning Lens. Screened. heat. I restored the lens once more, and had as an- 31i gg gtM nexed. 35 69I 6l\ And here the thermometer received 14. degree of heat again ; so that, in the course of 35 minutes, the thermometer N° 1 was alternately raised and depressed 5 times, by rays which came from the chimney fire, and were subject to laws of refraction, not sensibly different from those which affect light. Exper. 15. Refraction of the Heat of Red-hot Iron. — I caused a lump of iron to be forged into a cylinder of 24- inches diameter, and 24. inches long, fig. 9. This, being made red-hot, was stuck on an iron handle fixed on a stand, so as to present one of its circular faces to a lens placed at 2.8 inches distance; its focus being 1.4 inch, and diameter 1.1. Before the lens, at some distance, was placed a screen of wood, with a hole of an inch diameter in it, by way of limiting the object, that its image in the focus might not be larger than necessary. The screen also served to keep the heat from the thermometers. N° 2 was situated in the secondary focus of the lens; and N° 3 was placed within -^ of an inch of it, and at the same distance from the lens as N° 2. By this arrangement, both ther- mometers were equally within the reach of transmitted heat; or, if there was any difference, it could only be in favour of N° 3, as being behind a part of the lens which, on account of its thinness, would stop less heat than the middle. Now, as the experiment gives a result which differs from what would have arisen from the situation of the thermometers, on a supposition of transmitted heat, we can only ascribe it to a condensation of it by the refraction of the lens; and, in this case, the thermometer N° 3, by its situation, must have been partly within the reach of the heat-image formed in the focus. During the experiment, the thermometers were alternately screened 2 minutes from Open the effects of the lens, and exposed to it for Screened the same length of time; and the result Screened was as annexed. Here, in the first and 2d °Pen minutes, N° 2 gained 2° of heat more than N° 3. In the 3d and 4th, it lost 1 more than N° 3. In the 5th and 6th, it gained 1 more. In the 7th and 8th, it lost 14 more; and in the 9th and 10th, it gained -2- more than the other ther- mometer. This plainly indicates its being acted on by gcreenecj refracted heat. Lest there should remain a doubt on Open the subject, I now removed the lens, and, putting a open plain glass in the room of it, I repeated the experiment, Screened with all the rest of the apparatus in its former situation. pea Here we find, that both thermometers received heat and parted with it always in equal quantities, which confirms the experiment that has been given. And thus it is evident, that there are rays issuing from red-hot iron, which are subject to N°2. N°3. Min. In the Focus. Near the Focus, 0 56 56 2 62 60 4 59 58 6 61 59 8 58£ 57i 10 m 58| 0m 571 56| 2 62% 6l£ 4 60£ 60 6 61 60| 8 60 59k 10 60| 6"0£ 702 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. laws of refraction, nearly equal to those which affect light; and that these rays are invested with a power of causing heat in bodies. Exper. l6. Refraction of Fire-heat, by an Instrument resembling a Telescope. It occurred to me, that I might use a concave mirror, to condense the heat of the fire in the grate of my chimney, and, reflecting it sideways by a plain mirror, I might afterwards bring it to a secondary focus by a double convex lens ; and that, by this construction, I should have an instrument much like a Newtonian telescope, fig. 10. The thermometer would figuratively become the observer of heat, by being applied to the place where, in the real telescope of the same construction, the eye is situated to receive light. Having put together the different parts, in such a way as I supposed would answer the end, I tried the effect by a candle, in order to ascertain the proper distance of the object-mirror from the bars of the chimney-grate. The front of the apparatus was guarded by an iron plate, with a thick lining of wood; and the 2 thermometers which I used, were parted from the mirrors and lens by a partition, which screened them from the heat that was to be admitted through a proper opening in the front plate, to come at the object- mirror. In the partition was likewise an opening, of a sufficient diameter to permit the rays to come from the eye-glass to their focus, on the ball of the ther- mometer N° 1 ; while N° 4 was placed by the side of it, at less than half an inch distance. In the experiment, the mSo"^^ object-mirror was alternately covered by Covered a piece of pasteboard, and opened again. c^gred The thermometers were read off every Open minute; but, to shorten my account, I vere only give the last minute of every change. Here, in the first 8m, the thermome- ter exposed to the effects of the fire-instrument, gained 2° of heat more than the other. In the next 8 minutes, the mirror being covered, it gained 1° less than the other. The mirror being now opened again, it gained, in 5m, 2% degrees more than the other. When covered 6m, it gained l-f degree less than N° 4. In the next 10m, when open, it gained ± degree more; and, in the last 10m, when the fire began to fail, and the mirror was again covered, it lost 1° more than the other thermometer. All which can only be accounted for by the heat which came to the thermometer through the fire-instrument; and as this experiment confirms what has been said before of the refraction of culinary heat, so it also adds to what has already been proved of its reflection. For, in this fire-instrument, the rays which occasion heat could undergo no less than 2 reflections and 2 re- fractions. Exper. 17. Refraction of the Invisible Rays of Solar Heat. — I covered half of Mr. Dollond's burning lens with pasteboard, and threw the prismatic spectrum on that cover, fig. 7 ; then, keeping the last visible red colour -iV °f an inc" "*om N° 1. N°4. Min. In the Focus. Near the Focus. 0 77\ 77\ 8 84 76 16 9$k 79k 21 891 81 27 89| 82J 37 91| 83| 47 84 77 VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 703 the margin of the pasteboard, I let the invisible rays beyond the spectrum fall on the lens. In the focus of the red rays, or a very little beyond it, I had placed the ball of the thermometer N° 1 ; and, as near to it as convenient, the small one N° 2. Now, that the Min> In the Fo*cus. Near ^ j^ invisible solar rays which occasion heat were ac- 0 57 57 curately refracted to a focus, may be seen by the annexed account of the thermometers. Here, in lm, these rays gave 45° of heat to the thermometer N° 1, which received them in the focus, while the other, N° 2, suffered no change. It is remarkable, that notwithstanding I kept the red colour of the spectrum tl- of an inch on the pasteboard, a little of that colour might still be seen on the ball of the thermometer. This occasioned a surmise, that possibly the invisible rays of the sun might become visible, if they were pro- perly condensed; I therefore put this to the trial, as follows. Exper. 1 8. Trial to render the Invisible Rays of the Sun Visible by Condensation. — Leaving the arrangement of the apparatus as in the last experiment, I withdrew the lens, till the last visible red colour was -fa of an inch from M. N<3 0 the margin of the semi-circular pasteboard cover; then, taking o 57 57 the thermometers, I had as annexed. Here, there was no l 78 57 longer the least tinge of any colour, or vestige of light, to be seen on the ball of the thermometer; so that, in lm, it received 21° of heat, from rays that neither were visible before, nor could be rendered so by condensation. To account for the colour which may be seen in the focus, when the last visible red colour is less than fa of an inch from the margin of the pasteboard which in- tercepts the prismatic spectrum, we may suppose, that the imperfect refraction of a burning lens, which from its great diameter cannot bring rays to a geometrical focus, will bring some scattered ones to it, which ought not to come there. We may also admit, that the termination of a prismatic spectrum cannot be accurately ascertained, by looking at it in a room not sufficiently dark to make very faint tinges of colour visible. And, to this must be added, that the incipient red rays must actually be scattered over a considerable space, near the confines of the spectrum, on account of the breadth of the prism, the whole of which cannot bring its rays of any one colour properly together; nor can it separate the invisible rays entirely from the visible ones. For, as the red rays will be but faintly scattered in the beginning of the visible spectrum, so on the other hand will the invisible rays, separated by the parts of the prism that come next in succession, be mixed with the former red ones. Sir Isaac Newton has taken notice of some imperfect tinges or haziness, on each side of the prismatic spectrum, and mentions that he did not take them into his measures. Opt. p. 23, 1. II. Qocper. 1 9. Refraction of Invisible Culinary Heat. — There are some difficulties in this experiment; but they arise not so much from the nature of this kind of heat, as from our method of obtaining it in a detached state. A red-hot lump of 704 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. iron, when cooled so far as to be no longer visible, has but a feeble stock of heat remaining, and loses it very fast. A contrivance to renew and keep this heat might certainly be made, and I should indeed have attempted to carry some method or other of this kind into execution, had not the following trials appeared to me sufficiently conclusive to render it unnecessary. Admitting, as has been proved i the 15th experiment, that the alternate rising and Min ^0 ^ falling of a thermometer placed in the focus of a Screened 0 55 Very red-hot. lens, when the ball of it is successively exposed to, or g^ J »l ™;hot. screened from, its effects, is owing to the refraction Open 6 6o§ Still red. of the lens, and cannot be ascribed to a mere alter- Screened 8 57| A little red. ' , Open 10 59% Doubtful, nate transmission and stoppage of heat, I proceeded Screened 12 57k Not visible. as follows, fig. 9. My lens, 1.4 focus, and 1.1 gpen^ u 58| diameter, being placed 2.8 inches from the face of open 18 584 the heated cylinder of iron, the thermometer N° 2, Screened 20 57* 1 1111 ii Open 22 58 in its focus, was alternately guarded by a small paste- screened 24 57\ board screen put before it, and exposed to the effects Open 26 53 11 1 • -N.T J.L t- Screened 28 5/j of condensed heat by removing it. JNow, the be- ginning of this experiment being exactly like that of the 1 5th, with the ther- mometer N° 3 left out, the arguments that have before proved the refraction of heat in one state, will now hold good for the whole. For here we have a regular alternate rising and falling of the thermometer, from a bright red heat of the cy- linder, down to its weakest state of black heat; when the effect of the rays, condensed by the lens, exceeded but half a degree the loss of those that were stopped by it, Exper. 20. Confirmation of the 1 Qth. — In order to have some additional proof, besides the uniform and uninterrupted No 2 No 3 operation of the lens in the foregoing ex- Advanced sideways. T , ,, •.! Min. In the Focus. Always open. penment, I repeated the same, with an Screened 0 g2£ (,-3 r assistant thermometer, N° 3, placed first Open of all at 4 of an inch from N° 2, and Qcpr^ned more towards the lens, but so as to be Screened out of the converging pencil of its rays, ^^ned and also to allow room for the little Open screen between the 2 thermometers, that Screened N° 3 might not be covered by it. Here N° 3, being out of the reach of re- fraction, gradually acquired its maximum of heat, in consequence of an uniform exposure to the influence of the hot cylinder; after which it began to decline. N° 2, on the contrary, came to its maximum by alternate great elevations, and small depressions; and afterwards lost its heat by great depressions, and smallgele- vations. After the first 8m, I changed the place of the assistant thermometer, by putting it into a still more decisive situation ; for it was now placed by the side of 0 62| 63 1 63g 64 2 6<2i 64 3 64 64J 4 63| 64£ 5 6 64i 64| 64^ 64£ 7 64| 64 8 64£ 64 VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 705 that in the focus, so as to participate of the alternate screening, and also to receive a small share of one side of the invisible No 2 No 3 heat-image, which, though unseen, we Min. In the Focus. In the Edge of it. know must be formed in the focus of the ***£ ^ gj » lens. Here, if our reasoning be right, Open 11 64>\ 64 the assistant thermometer should be af~ greened 12 J <& 6s| fected by alternate risings and fallings; Screened 16 6"2£ 63 but they should not be so considerable as °Pen 18 63£ 63l those of the lens. Here the changes of the thermometer N° 2 were — 4. -f 4. — 14. + 4- — 1 + i ; and those of N° 3 were — 4. + .j. _ 4- -f i — 4. -f. 4. All which so clearly confirm the effect of the refraction of the lens, that it must now be evident that there are rays issuing from hot iron, which, though in a state of total invisibility, have a power of occasioning heat, and obey certain laws of re- fraction, very nearly the same with those that affect light. As we have now traced the rays which occasion heat, both solar and terrestrial, through all the varieties that were mentioned in the beginning of this paper, and have shown that in every state they are subject to the laws of reflection and of re- fraction, it will be easy to perceive that I have made good a proof of the first 3 of my propositions. For, the same experiments which have convinced us that, according to our 2d and 3d articles, heat is both reflexible and refrangible, establish also its radiant nature, and thus equally prove the first of them. Explanation of the Figures. — Plate 12, fig. 1, shews the arrangement of the apparatus used in the 2d experiment, a is the small mirror with its adjusting screws m, n. N° 2, is the thermometer in the focus of the mirror. N° 3, the assistant thermometer, b, a small screen for the thermometer N° 2. c, the candle, d, the poker which, in the 4th and 10th experiments, is to be placed in the situation of the candle 5 the rest of the apparatus being brought nearer to it. Fig. 2, shews the apparatus used in the 3d and 8th experiments, a, the mirror. N° 2, the ther- mometer, bcd, a desk adjustable to different altitudes, e, the prism receiving the sun's rays through an opening in the window shutter f. Fig. 3, a b is the front of the apparatus, which in the 5th experiment, is exposed to the fire of the chimney, c, is the opening in the front plate ab, for the admission of heat, d, is the small mirror which reflects the rays of heat, e, is the hole through which the heat passes to the thermometers. N° 1 and N° 4, are the thermometers, f, is a prism, which, in the 6th experiment, is to be placed in the room of the mirror d. Fig. 4, a, is the board that holds the apparatus used in the 7th experiment, b, the prism, c, the spectrum, thrown partly on the paper with parallel lines, and partly on one of the small tables which support the board, d, the mirror which reflects the rays of heat sideways. N° 1, the thermometer which receives the reflected rays. N° 2, the standard thermometer. Fig. 5, ab, is the front which, in the 9th experiment, is put close to the flat side of a heated iron stove, c, is the mirror, d, the feather-edged slip of deal, on two pins. N° 2, the thermometer which receives the rays condensed in the focus of the mirror. N° 3, the standard thermometer, e, a small screen tied to N° 3, to guard it from reflected heat. Fig. 6, A, the lens in the apparatus used for the 12th experiment. N* 2, the thermometer placed in its focus, b, the screen with an aperture for admitting the rays of heat, c, the eccentric pivot for turning away the lens, d, the candle. Fig. 7, a, the burning lens, covered ; with the prismatic spectrum thrown on an opening, left for it, in VOL. XVIII. 4 X 706 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. the pasteboard cover of the 13th experiment. N° 3, the thermometer placed in its focus, a, the prism. c, semicircular cover, used in the 17th and 18th experiments, instead of the one with a square hole. Fig. 8, a, the burning lens of the 14th experiment, b, the fire in the chimney. N° I, the ther- mometer in the focus of the lens. N° 4, the standard thermometer, c, the hole through which the rays of heat pass to N° 1. d and e, two holes, between which the ball of the thermometer N° 4 is screened from the direct rays of the fire ; while free access is given to the heat which may affect the temperature of the place. Fig. 9, a, the iron cylinder, stuck on its handle, as it is used in the 15th and 19th experiments, b, the lens, c, the screen with an opening in it. N° 2, the thermometer in the focus of the lens. N°3, the standard thermometer, d, the little moveable pasteboard screen. Fig. 10, a b, the front, plated with iron, that it may bear to be exposed close to the bars of a chimney fire, c, the concave mirror, d, the plain mirror, e, the lens. N° 1, the thermometer in the focus of the lens. N° 4, the standard thermometer, f, a circular opening in the front plate a b, for ad- mitting the rays of heat to fall on the concave mirror c. m, the first focus of the rays, from which they go on diverging, to the small mirror, and to the lens ; which brings them to a 2d focus, on the ball of the thermometer N° 1. XVI. Chemical Experiments on Zoophytes ; with some Observations on the Com- ponent Parts of Membrane. By Chas. Hatchett, Esq. F. R. S. p. 327. The experiments and observations on shell and bone, which I last year laid be- fore the r. s., were made in consequence of my having a little before discovered that the enamel of teeth did not consist principally of carbonate of lime, but was of a nature similar to bone ; with this difference, that the phosphate of lime was not deposited in and upon a cartilaginous or membranaceous substance, but was only blended with a certain portion of animal gluten. By the experiments subse- quently made on various shells, crustaceous substances, and bones, it was proved, 1st. That the porcellaneous shells resemble the enamel of teeth in the mode of formation, but that the hardening substance is carbonate of lime. 2dly. That shells composed of nacre or mother of pearl, or approaching to the nature of that substance, and also pearls, resemble bone in a considerable degree, as they consist of a gelatinous, cartilaginous, or membranaceous substance, forming a series of gradations, from a tender and scarcely perceptible jelly to membranes completely organized, in and upon which carbonate of lime is secreted and deposited, after the manner that phosphate of lime is in the bones; and therefore, as the porcella- neous shells resemble the enamel of teeth, so the shells formed of mother of pearl, &c. in like manner resemble bone; the distinguishing chemical character of the shells being carbonate of lime, and that of enamel and bones being phosphate of lime. 3dly. It was proved, that the crust which covers certain marine animals, such as crabs, lobsters, crayfish, and prawns, consists of a strong cartilage, hardened by a mixture of carbonate and phosphate of lime; and that thus these crustaceous bodies occupy a middle place between shell and bone, though they incline prin- cipally to the nature of shell. And, 4thly. That a certain portion of carbonate of lime enters the composition of bones in general ; the proportion of it however being, to the phosphate of lime, vice versa to that observed in the crustaceous marine VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 707 substances. On the view therefore of these facts it is evident, that there is a great similarity in the construction of shell and bone; and that there is even an ap- proximation in the nature of their composition, by the intermediate crustaceous substances. These remarks, with the experiments by which they are supported, form the principal features of that paper, which was honoured with a place in the last vol. of the Phil. Trans. At that time, it was not my intention immediately to pursue the subject; but I changed this resolution, after a conversation with Dr. Gray, Sec. e. s., who suggested, that many marine substances still remained to be ex- amined in a similar manner; and that a series of experiments on zoophytes, hitherto but little known in respect to their component parts, would be very in- teresting, and might probably lead to some improvement in their classification. I was therefore induced to make the experiments contained in the following pages; and as the mode adopted was very similar to that which was formerly pursued, it appears superfluous here to repeat the description. It will be proper however to observe, that argill is not unfrequently lodged, as an extraneous substance, in the interstices of many of the madrepores, and such like bodies; and, as argill is pre- cipitated by pure ammonia, it became necessary not to rely merely on the ammo- nia, as a test of phosphate of lime. Whenever therefore any precipitate was pro- duced by ammonia, it was dissolved again in acetous acid, and this solution was examined by the addition of acetite of lead. § 1. EXPERIMENTS ON ZOOPHYTES. Madrepora virginea*. — This madrepore, when immersed in very dilute nitric acid, effervesced much, and was soon dissolved. The solution was perfectly trans- parent and colourless, with but a small appearance of gelatinous or membranaceous particles. Pure ammonia was then added, but did not cause any alteration; and the whole of what had been dissolved, was afterwards completely precipitated by carbonate of ammonia, and proved to be carbonate of lime. Madrepora muricata. — When treated like the former, this afforded some loose particles of a gelatinous substance: these were separated by a filter, and the solution was supersaturated with pure ammonia, without effect; but on adding car- bonate of ammonia, the dissolved part was precipitated, in the state of carbonate of lime. Madrepora labyrinthica. — This, being examined in the manner above-mentioned, proved to be composed of carbonate of lime, and of a loose gelatinous substance, similar to that afforded by madrepora muricata. Madrepora ramea. — When this madrepore was first immersed in very dilute nitric acid, a considerable effervescence was produced ; and after a few hours a pale brown fibrous membrane remained, which in some measure exhibited the original * The different species are named according to Gmelin's edition of Linnaeus's Systema Naturae.— Orig. 4x2 708 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. figure of tlie madrepore. The clear solution being poured into another vessel only afforded a large quantity of carbonate of lime. Madrepora fascicularis. — When this was put into very dilute nitric acid, a con- siderable effervescence arose; and after some hours a tender membrane was left which retained the original shape. Pure ammonia did not disturb the transparency of this solution; but a copious precipitate of carbonate of lime was obtained, by the addition of carbonate of ammonia. These experiments, on only a few of the madrepores, sufficiently prove how similar they are, in composition, to shell; for both consist of the same materials, subject to the like modifications. Millepora ccerulea. — This produced much effervescence, when immersed in very dilute nitric acid. The blue colour disappeared, as the calcareous part was dis- solved, and was not afterwards restored by ammonia. Some loose detached portions of a gelatinous substance floated in the solution, which were separated by a filter. The transparency of the solution was not disturbed by pure ammonia; but a copious precipitate of carbonate of lime was produced by carbonate of pot-ash. Millepora alcicornis. — This millepore, when treated with very dilute nitric acid, produced a great effervescence; and after a few hours a tender gelatinous substance remained, which did not retain the figure of the millepore. Pure ammonia had not any effect; but carbonate of ammonia precipitated a large quantity of car- bonate of lime. Millepora polymorpha. — This produced an effervescence when put into dilute nitric acid; and after some hours a substance remained, which completely retained the original figure of the millepore. The substance which thus remained, was composed of a strong white opaque membrane, which formed the external part; the interior of this was filled with a transparent gelatinous substance. Ammonia produced a very slight precipitate, which, being dissolved in acetous acid, was proved to be phosphate of lime, by solution of acetite of lead. Carbonate of soda afterwards precipitated a large quantity of carbonate of lime. Millepora cellulosa. — This millepore effervesced much with dilute nitric acid; and when this had ceased, a finely perforated membrane remained, in structure and appearance like the original substance. Ammonia did not produce any effect; but a large quantity of carbonate of lime was obtained by carbonate of soda. Millepora fascia lis. — Th is resembled the former in every particular; and left a membrane perfectly like the millepore. Millepora truncata. — When treated with dilute nitric acid, it effervesced much, like the former; and after a few hours a semi-transparent membranaceous substance remained, which exhibited completely the shape and structure of the original mille- pore. Ammonia did not disturb the transparency of the solution ; but the whole of the dissolved portion was precipitated, in the state of carbonate of lime, by carbonate of ammonia. The remark lately made on the madrepores may here also be repeated, as the composition of the millepores appears to be the same, with the single exception of VOL. XC.] PHILOSOPHICAL TBANSACTIONS. JOQ millepora polymorpha, which afforded some slight traces of phosphate of lime. But time and future experiments will show whether this was an accidental circum- stance, or whether the millepore polymorpha is thus distinctly characterised. It is likewise necessary to add, that when these various madrepores and millepores were exposed to red heat, in a crucible, they emitted smoke, with the smell of burnt horn or feathers, became tinged with a paler or deeper gray colour, and when dis- solved in acids deposited more or less animal coal, in proportion to the quantity of the gelatinous or membranaceous substance detected by the experiments lately described*. Tubipora musica. — Of the tubiporae, I had only an opportunity to examine this species. Like the former substances, it was immersed in an acid, and on this oc- casion I employed the acetous acid. A great effervescence was produced, and the red colour was destroyed, in proportion as the calcareous part was dissolved. When the solution was completely effected, some loose particles of a tender membrane floated in the liquor, and were separated by a filter. Pure ammonia added to the solution, produced a precipitate; which proved to be argill, accidentally lodged in the interstices of the tubipore. To the filtrated liquor, carbonate of potash was added, and precipitated a large quantity of carbonate of lime. Flustra foliacea. — When this was immersed in very dilute nitric acid, an effer- vescence of short duration took place; and, when this had ceased, the flustra ap- peared like a finely reticulated membrane, which retained the original shape. Pure ammonia being added to the filtrated solution, produced a slight precipitate; which, being dissolved in acetous acid, was proved, by acetite of lead, to be phosphate of lime. Solution of carbonate of ammonia was then added to the liquor from which the phosphate of lime had been separated, and produced a copious precipitate of carbonate of lime. When the flustra foliacea was exposed to a low red heat, in a crucible, it emitted a smell like burnt horn, but retained its shape, by reason of the carbonate of lime with which it was coated. The flustra thus burnt, when dissolved in dilute nitric acid, deposited some animal coal ; but in other respects the present solution resembled the former nitric solution of this substance when in a recent state. The flustra foliacea, when long digested with boiling distilled water, communicated to it a pale brownish tinge. Infusion of oak bark being then poured into the liquor, did not produce any visible effect, even after 24 hours had elapsed; but nitro-muriate of tin formed a white cloud, in the space of a few minutes. Corallina Opuntia. — This being put into very dilute nitric acid, produced, like the flustra foliacea, an effervescence of short duration. The coralline then re- mained in a membranaceous state, and retained the original figure. To the filtra- ted solution some pure ammonia was added, but it scarcely produced any visible * The order in which these experiments are placed, is not that according to which they were made; but it has been adopted, because it shows more evidently the gradations of the membranaceous sub- stances.— Orig. 710 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. effect. Carbonate of ammonia precipitated a large quantity of carbonate of lime. Some of the corallina opuntia was then exposed to a low red heat, in a crucible; it emitted a smell of burnt horn, and in great measure retained its shape, evidently from the calcareous coating. The burnt coralline, being dissolved in dilute nitric acid, deposited some animal coal. The clear solution afforded, by pure ammonia a very slight precipitate of phosphate of lime; after which, the carbonate of lime was precipitated as before. This coralline, when treated with boiling water, like the flustra foliacea, did not discolour it; neither was the water changed by infusion of oak bark ; but nitro-muriate of tin produced a faint white cloud. Isis ochracea. — When this isis was immersed in dilute nitric acid, a considerable effervescence was produced ; and, in proportion as the calcareous substance was dis- solved, the red colouring matter was deposited, in the state of a fine red powder*. When the effervescence had ceased, which was after about 3 hours, a yellowish membrane remained, which completely retained the original figure of the isis. The solution, being filtrated, was saturated with pure ammonia by which a slight pre- cipitate of phosphate of lime was separated. A large quantity of carbonate of lime was afterwards precipitated, by solution of carbonate of potash. Part of a branch of this isis was put into a crucible heated to a low red heat. A great quantity of smoke was emitted, which had the smell of burnt horn; and after a few minutes the branch separated at the knotty joints, into as many pieces as there were joints in the branch. These joints had all the characters of coral; but the whole of the membrane which had invested them, as well as the knotted protuberances by which they had been connected, were destroyed, by being con- verted into coal. From this circumstance, I was desirous to examine the internal structure of the membranaceous part, out of which these joints of coral had been dissolved by acids. I took, therefore, the membranaceous substance which remained after the first experiment, and which retained the complete figure of the isis. This substance being opened longitudinally, exhibited a series of cavities, corresponding in form with the coralline joints, and so situated, that each of these cavities extended from one bulb or knot nearly to the next, throughout the whole of the branch. The coralline joints, when viewed separately, appeared smaller in the middle than at the ends, which were terminated by obtuse cones. In the branch these joints were so placed, that the extremities or' cones were opposed point to point ; but were prevented from immediate contact, by a gristly substance, which filled, and indeed principally formed in the branch, the knot or bulb of each joint, and was interposed between the cones of the coralline substance, like the common carti- lages of the articulations. From this construction it appears, that the isis is capable of great flexibility • This colouring substance was not dissolved, nor changed, when nitric or muriatic acid was poured on it. It appears therefore to be very different from the tinging matter of the tubipora musica, or that ©f the Gorgonia nobilis.— -Orig. VOL. XC.] PHILOSOPHICAL TRANSACTIONS. J\\ when in a recent state; for the gristly part of the bulbs is then most probably much softer, and more elastic, than it appears to be in the dried specimens which are found in collections*. This gristly substance which forms the bulbs, and the coralline joints, are kept together, and are covered, by a thin skin or membrane, which is continued over the whole, like a tube. The joints are not therefore de- void of a coating, as seems to be implied by the definition of Linnaeus. hit Hippuris. — Part of a branch of the isis was immersed in very dilute nitric acid, and a considerable effervescence immediately took place. When this effer- vescence had ceased, there appeared little or no change in the original form of the isis; but the coralline joints were now become a soft, compact, white, and opaque membranaceous substance; while the dark brown intermediate parts retained also their form, and in other characters resembled those of horn. The solution was colour- less and transparent. When saturated with pure ammonia, it was not affected; but carbonate of pot-ash produced a copious precipitate of carbonate of lime. Another part of this isis was exposed to a low red heat, in a crucible. The dark brown horny parts swelled, and puffed up, with much smoke, and a smell like that of burnt horn. The coralline joints also emitted the same smoke and smell, and became dark gray. When put into dilute nitric acid, a solution was made, with effervescence, during which, there was a copious deposition of animal coal. From this solution, nothing but carbonate of lime was obtained by the usual pre- cipitants. A tube of membrane invests the curious structure of the isis ochracea; but no such tube or outer coat exists in the isis hippuris ; for the coralline joints, like those of the madrepores, millepores, &c. consists of a membranaceous substance, hardened by carbonate of lime, and the only difference appears to be; that in the madrepores and millepores, the membranaceous part is less compact and abundant; but even the striae of the coralline joints remain visible, and unchanged, in the membrane of this isis. The brown horny part forms also a marked characteristic in this isis, and seems to approach it to certain of the gorgoniae. This horny part does not however pervade the whole of the branch ; for where the coralline joints commence, this horny substance immediately terminates, internally as well as ex- ternally, and is not to be discovered but between or in the separation of these joints. Gorgonia nobilis. — I next proceeded to examine the gorgonia nobilis or red coral ; and of this I separately subjected to experiment different pieces, some of which were polished, and deprived of their external pale red mealy coat, while others were in their original state. A piece of the unpolished red coral being put into dilute nitric acid, an effervescence immediately took place; and after some hours the whole of the calcareous substance was completely dissolved. The external coat retained the original figure, and appeared like a pale yellow tubulated membrane, • It must here be observed, that the articulated structure above-mentioned, is not to be found in those parts which form the main stem, with its larger branches; the joints in those parts being consoli- dated, so as to constitute a strong and rigid trunk, on which the whole fabric is supported. — Orig. 712 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. the interior of which was filled with a transparent gelatinous substance. From the solution I only obtained a large quantity of carbonate of lime. The next ex- periment was made in a manner exactly similar to the former; but a piece of the polished or uncoated red coral was now taken. The effects produced by the di- luted acid were the same as before; but in the solution some loose portions of a transparent yellow gelatinous substance were now only to be seen. The nitrated solution was treated as in the former experiment, and afforded a considerable quantity of carbonate of lime. As it was possible that the action of the nitric acid, though much diluted, might be too powerful, I was induced to try the effects of acetous acid, in which I immersed a piece of the red coral fn its natural state. It was gradually dissolved, with a slow effervescence, and left an external tubulated membrane, retaining the original form, and filled with a transparent gelatinous substance, as in the first experiment. The solution, when filtrated, afforded car- bonate of lime. A piece of the polished or uncoated red coral was treated with acetous acid, in a similar manner. It was slowly dissolved, and left a transparent gelatinous substance like that which has already been mentioned, excepting that it was not in detached portions. This solution, like the former, only yielded carbonate of lime. It may here be observed, that in each of the above related experiments, the red colour of the coral was gradually destroyed, as the solution of the calcareous substance ad- vanced, and could not afterwards by any means be restored; nor could any colour- ing principle whatever be detected by the re-agents usually employed. A piece of red coral, in its natural or uncoated state, was exposed to a low red heat, in a crucible, during about 10 minutes, at which time a faint smell of burnt horn was to be perceived. When the coral was taken out of the crucible, it had completely lost the red colour, and was become pale gray. It dissolved in dilute nitric acid, with effervescence, and some animal coal was separated. To the filtra- ted solution pure ammonia was added, and produced a very slight precipitate, which was collected, and was afterwards dissolved in acetous acid. From this solution, by the addition of acetite of lead, some phosphate of lead was obtained. The carbonate of lime was afterwards precipitated in the usual manner. As the very small portion of phosphate of lime discovered in the preceding experiment, and which had escaped the action of the acids then employed, might be only contained in the coating or epidermis, a piece of the polished or uncoated coral was treated in a similar manner; but on examining the solution it afforded a small portion of phosphate, with a large quantity of carbonate of lime; so that the result of this experiment did not differ from that of the former. From the preceding experiments it appears, that the gorgonia nobilis or red coral, consists of 2 parts; one of which is the stem, formed of a gelatinous substance, hardened by carbonate of lime, and coloured by some unknown modification of animal matter; the other is a membranaceous tube, which, like a cuticle or cortex, coats the stem above-mentioned, and, when deprived of its hardening substance, VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 713 possesses all the characters of membrane. But though carbonate of lime could only be discovered when this gorgonia was simply immersed in acids, yet it had been proved by these experiments, that a small portion of phosphate of lime is also present, but so enveloped by the membranaceous and gelatinous parts, as not to be dissolved by the acid menstrua, till these substances have been decomposed by fire. This is not an unusual circumstance, when a very small portion of a substance is enveloped by large quantities of other matter; for Bergmann, in his supplement to Scheele's Essay on the Calculus Vesicae, observes, that the presence of calcareous earth in certain calculi, could not be discovered in the usual manner, but by operations made expressly for the purpose. 1 do not pretend to determine whether the very small portion of phosphate of lime in the gorgonia nobilis is an essential ingredient or not; but the mode of construction evidently proves how much this gorgonia differs from the madrepores and millepores, as well as from the gorgoniae about to be mentioned. Gorgonia ceratophyta. — When this was immersed in dilute nitric acid, an effer- vescence was produced; after which, the cortical part appeared like a thin yellowish membrane investing the stem, which was become transparent, and similar to car- tilage. Ammonia precipitated from the solution a large quantity of phosphate of lime ; and lixivium of pot-ash separated some carbonate of lime. A quantity of the cortex (which had been separated from the stem by beating it between folded writing paper) was steeped in the dilute acid. This solution afterwards, with am- monia, scarcely afforded a vestige of phosphate of lime ; but when lixivium of car- bonate of pot-ash was added, a considerable quantity of carbonate of lime was ob- tained. The stem, on the contrary, when thus treated, afforded much phosphate of lime, and very little of the carbonate. When burned in a crucible, it smoked, and emitted a smell like burnt horn, but the figure was not destroyed; and, when afterwards dissolved in the acid, it yielded the same products as before. Gorgonia Jiabellum. — When this gorgonia was steeped in dilute nitric acid, it produced an effervescence of a short duration. The cortical part then appeared like a thin yellowish membrane, which covered the stem. The latter was trans- parent, and resembled softened horn of a reddish brown colour. The solution afforded a large quantity of phosphate of lime, by the addition of ammonia ; after which, lixivium of potash formed a less copious precipitate of carbonate of lime. Some parts of the cortex were separated, by beating the gorgonia between folded writing paper, and were immersed in the acid. This solution was scarcely rendered turbid by ammonia ; but afforded a considerable portion of carbonate of lime by potash. The stem from which the above cortical part had been separated, was next examined by the dilute acid, in which, when steeped during 3 days, it became soft, elastic, and in some measure cartilaginous. The acid was saturated with pure ammonia, and then changed to a deep yellow or orange colour: a large quantity of phosphate of lime was at the same time separated ; and but very little carbonate of lime was afterwards precipitated by potash. The recent stem in great vol. xvin, 4 Y 714 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. measure retained its shape, when put fnto a red-hot crucible ; but that which had been steeped in the acid, curled up, and soon became a shapeless mass of coal, which, by a longer continuation of the red-heat, was completely dissipated. This difference appears to have been caused by the phosphate of lime, which was present in the recent stem, but was dissolved and separated in the latter case by the acid*. The experiments prove, that the gorgonia flabellum, like the gorgonia cerato- phyta, consists of a horny stem, containing a certain portion of phosphate of lime ; and that this stem is invested with a membrane, hardened principally by carbonate of lime, which serves to cover and defend it, in the manner of a shell-|-. Gorgonia suberosa. — The cortical part of this gorgonia was separated from the stem, and was first subjected to experiment. Some portions of this cortex were immersed in dilute nitric acid ; and after an effervescence, which continued several hours, a soft yellowish membranaceous substance remained, retaining the original figure. The liquor decanted was pale yellow, which colour was much deepened by the addition of ammonia ; at the same time a small quantity of phosphate of lime was deposited. A considerable portion of carbonate of lime was afterwards precipitated by carbonate of potash. Some pieces of the cortex were boiled with distilled water for about 6 hours ; and to the filtrated liquor infusion of oak bark was added, by which a large quantity of gelatin was precipitated. The same pieces were afterwards boiled with lixivium of caustic potash, which effected a perfect solution, and formed the animal soap of Chaptal ; at the same time, the calcareous matter subsided to the bottom of the matrass. The cortical part of this gorgonia, when put into a red-hot crucible, emitted much smoke, with a smell like horn that is burnt ; after this it fell into pieces, which, being dissolved in nitric acid, afforded a small portion of phosphate of lime, and a large quantity of carbonate of lime. When the stem of this gorgonia was steeped during 14 or 15 days in dilute nitric acid, it tinged it with pale yellow. The stem after this appeared more transparent and flexible, so as to approach the characters of car- tilage. The yellow liquor was changed to a deep yellow or orange colour by the addition of ammonia ; but did not yield any precipitate, even when carbonate of potash was added. Part of a stem was cut into small pieces, and was boiled for several hours with distilled water. When filtrated, the water had acquired a very pale yellow tinge ; and, on the addition of infusion of oak bark, yielded a slight precipitate of gelatin. Lixivium of caustic potash was then poured on the same pieces; and being boiled, a thick dark-coloured viscid substance was formed, » These different effects are to be observed, when bone, and when the cartilage or membrane which remains after bone has been long steeped in acids, are subjected to a red heat. + It may here be proper to observe, that the membranaceous part of all these substances, such as the madrepores, millepores, flustra, &c. &c. was dissolved, when these bodies were boiled with, lixivium of caustic potash j and animal soap was formed. The same may also be said of shells ; and Mr. Van Mons has noticed this effect on those of the oyster. See Annales de Chiniie, tome 31, p. 123.— Orig. TOL. XC.] PHILOSOPHICAL TRANSACTIONS. 715 which possessed all the characters of Chaptal's animal soap. When the stem of this gorgonia was exposed to a red heat in a retort, or crucible, it curled up, and smelled like burnt horn ; after which, a spongy coal remained, of difficult inci- neration. By a long continuation of the heat, a residuum was left, so small as scarcely to be collected, which, being dissolved in dilute nitric acid, afforded, by the addition of ammonia, a slight precipitate of phosphate of lime. Another species of gorgonia, which much resembled the suberosa, excepting that the cortical part was much larger in proportion to the stem, was next subjected to examination, and proved to be of a similar composition with those already mentioned. Gorgonia pectinata. — The cortical part of this gorgonia effervesced with dilute nitric acid, and left a soft yellowish white membrane. Ammonia precipitated a small quantity of phosphate of lime ; after which a copious precipitate of carbo- nate of lime was obtained by potash. The stem, in its habits, resembled those which have been described. Gorgonia setosa. — An effervescence was produced on the immersion of this gorgonia in dilute nitric acid ; and after some hours the cortical part appeared like a thin yellowish membrane, which coated the horny stem. The acid solution, on the addition of ammonia, yielded a slight precipitate of phosphate of lime ; and a large quantity of carbonate of lime was afterwards obtained by potash. When the cortex was separately steeped in the acid, and the solution examined in the way so often mentioned, only carbonate of lime was obtained*. On the contrary, the stem, whether recent or burnt, afforded a small portion of phosphate of lime, but scarcely any trace of carbonate. The stem which had been long steeped in the acid, became soft and transparent, like a cartilaginous or tendinous substance. The gorgoniae which have been enumerated, much resemble each other in the composition of their cortices, as well as in the nature of their stems. In the cortex, the predominant hardening substance is carbonate of lime ; but in the stem phosphate of lime is the chief and almost the only earthy substance that is present. The following gorgoniae, though in like manner invested by a cortex, are different, as they do not afford any phosphate of lime. Gorgonia umbraculum, g. verrucosa, and 3 other species not described, so much resemble each other in their chemical characters, that it would be superfluous to give a separate account of them. The cortical parts of these gorgoniae were separately immersed in dilute nitric acid. An effervescence immediately took place, and after some time they were found in the state of soft pulpy yellowish white membranaceous bodies, retaining nearly their original size and form. The acid solutions did not afford any phosphate of lime when ammonia was added ; but a large portion of carbonate of lime was precipitated by solution of potash. The stems of these gorgoniae, * When the cortical part had been long digested in boiling distilled water, a brownish solution was formed, which was but little affected by infusion of oak bark ; but nitro-muriate of tin produced a precipitate — Orig. 4 Y2 7l6 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. when immersed 14 days or more in the dilute acid, were very little affected, ex- cepting that they became softer and transparent, so as to approach the characters of cartilage or softened horn*. The acid in which they had separately been steeped, did not afford any precipitate by the addition of the alkalies ; and the only change was in the colour, which became deep yellow when ammonia was added. The gorgoniae now to be mentioned differ from the former, as they are not coated with a fleshy or pulpy cortical substance. They are here placed immediately before the antipathes, on account of their great similarity in chemical properties, as well as in external appearance. Gorgonia antipathes. — Some pieces of this gorgonia were immersed in dilute nitric acid 3 weeks, at the end of which time they were much softened, and ap- peared to be composed of a pale brown opaque membranaceous substance, which formed concentrical coats, of a ligneous aspect. The acid in which these pieces had been steeped, was become pale yellow, and changed to orange colour when ammonia was added ; but not the smallest precipitate could be thus obtained ; nor was any alteration caused by the addition of lixivium of potash. When distilled water was boiled with the gorgonia antipathes about 6 hours, it became slightly tinged with yellow ; and some infusion of oak bark being added, a small quantity of gelatin was precipitated. The pieces of this substance which had been thus treated, were afterwards boiled with lixivium of caustic potash, by which the whole was dissolved, and a very dark coloured animal soap was formed. When this gorgonia was exposed to a red heat, it emitted much smoke, with a smell of burnt horn : it soon lost its shape, puffed up, and formed a spongy coal, which, by a long continued heat, left a few particles of a white substance, consisting chiefly of muriate of soda. Another species of gorgonia was next examined, the stem of which is from -^ to nearly 4- an inch in diameter in the thickest parts; it is of a black colour, and a high polish, like black sealing wax : it has probably been considered as a variety of gorgonia antipathes. This by immersion for 28 days in dilute nitric acid, gra- dually became semi-transparent, and of a bright brownish yellow. In this softened state, it was steeped 2 days in water, and was then opened longitudinally. By this the whole structure became apparent, and consisted of thin coats or tubes of a beautiful transparent membrane, which, beginning from a central point, progres- sively became larger, according to the order by which they receded from the centre. These membranes were so delicate, that the fibrous texture could scarcely be dis- cerned. The acid in which this species had been steeped was tinged with very pale yellow. Ammonia being added, changed it to a deep yellow or orange colour ; but the transparency of the liquor was not disturbed by this, or any of the other precipitants which had been employed in the former experiments. When this * The stems of the various gorgoniae, which had been thus softened by long immersion in dilute nitric acid, became of a deep reddish orange colour, inclining to brown, when subsequently steeped in pure ammonia } and in the course of a few hours they were completely dissolved.— Orig. VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 717 gorgonia was exposed to a red heat, it crackled, and emitted a thick smoke, with the smell of burnt horn. The shape was soon destroyed, and a compact coal remained. By continuing the red heat, a very small portion of white matter was obtained, which, as far as the quantity would allow, was proved to be muriate of soda, with some carbonate of the same. The last species of gorgonia which I shall here mention, is one which so much resembles the gorgonia antipathes as not easily to be distinguished from it, and, like the preceding, has probably been confounded with it ; but on closely com- paring them, the gorgonia now treated of is found to be more fiat in the stem, on the thin sides or edges of which a number of short spines or protuberances are placed very near each other. That it is very different from the gorgonia anti- pathes, will be proved by the subsequent experiments. Some pieces of this gor- gonia were exposed to the action of dilute nitric acid for nearly 4 weeks. The structure then became very apparent, and consisted of strong fibres, which were placed nearly in a parallel direction, from one extremity of the branch to the other, and, being closely arranged side by side, formed concentric coats of a pale brown opaque substance ; but these coats were by no means so distinct as those observed in the gorgoniae formerly mentioned, though like them the fibrous sub- stance possessed the characters of membrane. The dilute acid in which these pieces had been steeped, was become pale yellow, which changed to orange colour when ammonia was added ; at the same time so large a quantity of phosphate of lime was precipitated, that the liquor became thick and viscid. The phosphate was separated by a filter ; and lixivium of potash was added to the clear liquor, without producing any effect. This gorgonia was digested in boiling distilled water during 1 8 hours, and tinged it with pale, yellow. Infusion of oak bark was then poured into the liquor, and precipitated a small portion of gelatin. The pieces employed in the above ex- periment were next boiled with lixivium of caustic potash, and formed a dark- coloured animal soap ; at the same time the phosphate of lime was separated, and was gradually deposited at the bottom of the matrass. Part of a large branch of this gorgonia was exposed to a low red heat. It immediately emitted a thick smoke, with the smell of burnt horn ; and after a long continued heat the phos- phate of lime was left, so as to retain the original figure, like bone which has been burned ; but, in the present instance, the particles of the mass cohered but feebly. When this residuum was dissolved, and the phosphate separated in the usual manner, a slight cloud of carbonate of lime was produced by potash. Antipathes Ulex. — When this had been immersed 14 days in dilute nitric acid, it became transparent, and so much softened, that from a horny substance it now nearly resembled cartilage. The acid in which it had been steeped, changed to a very deep yellow or orange colour when ammonia was added ; but no precipitate could be obtained by this, or by potash. A portion of this antipathes was di- gested with boiling distilled water, from which some gelatin was precipitated after- 718 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800.* wards by infusion of oak bark. The antipathes being then boiled with lixivium of caustic potash, was completely dissolved, and formed the animal soap of Mr. Chaptal. Antipathes myriophylla. — This was subjected to experiments like those above related, and as the effects were the same, it is not necessary that particular men- tion should here be made of them. As the specimens of these antipathes were small, I was not able to make any additional experiments ; but what has been said sufficiently proves how much they resemble the horny stems of the gorgoniae. Sponges. — Many species of sponge were examined, but as little or no essential difference was found in the results, I shall include them all in what is now to be related. The following species, with many others not described, were subjected to experiment. Spongia cancellata. Sp. oculata. Sp. infundibuliformis. Sp. palmata. Sp. officinalis. When the sponges had been immersed in nitric acid, diluted with 3 measures of distilled water, during 14 or l6 days, the acid became pale yellow, and was changed to an orange colour by the addition of pure am- monia. The sponges which had been thus steeped in the dilute acid, became, like the gorgoniae, more or less transparent, and were considerably softened. In this state, if they were touched with ammonia, the part thus touched became of a deep orange colour, inclining to a brownish red ; and when much softened by the acid, if afterwards immersed in ammonia, they were completely dissolved, and formed a deep orange-coloured solution*. When digested with boiling distilled water, the sponges afforded a portion of animal jelly or gelatin, which was pre- cipitated by infusion of oak bark. The fine and more flexible sponges yielded gelatin in greater abundance, and more easily, than those which were coarse and rigid. The gelatin was gradually and progressively imparted to the water, and seems, even in the same sponge, to be a constituent principle, of different degrees of solubility ; and it must be noticed, that in proportion as the sponges, parti- cularly those which were soft and flexible, were deprived of this substance, in the like proportion they became less flexible and more rigid, so that the remaining part, when dry, crumbled between the fingers ; or, when moist, was torn easily, like wetted paper. As the above properties prove that sponges only differ from the horny stems of the gorgoniae, and from the antipathes, by being of a finer and more closely woven texture-f-, so this similarity will be corroborated by the following remarks. When exposed to heat, they yielded the same products, the same smell, and afforded a similar coal, which by incineration left a very small residuum, consisting chiefly of muriate of soda, occasionally mixed with some carbonate of lime, which was also often discovered when the recent sponges were * The same effects were observed when the horny stems of the gorgoniae, antipathes, &c. which had been long steeped in dilute nitric acid, were immersed in pure or caustic ammonia. f This is particularly to be observed by comparing the coarse sponges, such as spongia cancellata, with the finely reticulated parts of certain gorgoniae, especially those of gorgonia flabellum, when divested of the external membrane. — Orig. VOL. XC.] PHILOSOPHICAL TRANSACTIONS. JlQ immersed in acids ; but this, as well as the muriate of soda, is I believe merely extraneous, and arises from small shells, parts of madrepores, and such like bodies, which are often visibly lodged in the interstices of the sponges. Lastly, the sponges, when boiled with lixivium of caustic potash, were completely dissolved, and, like the horny stems of the gorgoniae, formed animal soap, more especially when the part which is apparently insoluble in water, and which remains after the gelatin has been separated, was thus treated. Alcyonium asbestinum. — This, after being immersed several hours in dilute nitric acid, remained unchanged in figure ; a feeble effervescence was at first produced, and the reddish purple colour was destroyed. The external part became pale yellow, and was a soft opaque pulpy substance, within which was a stem, very similar in texture, but less soft, and which still appeared of a pale red colour. When pure ammonia was added to the filtrated solution, no apparent effect was produced; but carbonate of potash precipitated a large quantity of carbonate of lime. When a piece of this alcyonium was exposed to a low red heat, it soon took fire, and emitted a smell like burnt horn ; after which it retained its figure, and became white. Being dissolved in dilute nitric acid, some animal coal was deposited ; and on the addition of ammonia a small portion of phosphate of lime was obtained, which being separated, the carbonate was precipitated as before. Some pieces of this alcyonium were digested with boiling distilled water for 6 hours; the liquor was then decanted, and infusion of oak bark being added, a quantity of gelatin was precipitated. On the pieces of the alcyonium from which the water had been decanted, some lixivium of caustic potash was poured; and being boiled, the whole of the membranaceous or pulpy part was dissolved, and a substance exactly similar to Chaptal's animal soap was formed, while the calcareous part subsided to the bottom of the vessel. Alcyonium Jicus. — When the effervescence produced by pouring dilute nitric acid on this alcygnium had ceased, it was found unchanged in shape, and like a strong thick membranaceous substance of a fibrous texture. Pure ammonia, added to the acid liquor, precipitated a small quantity of phosphate of lime ; after which a copious precipitate of carbonate of lime was obtained by potash. Alcyonium arboreum. — This alcyonium, being steeped in the dilute nitric acid, effervesced, and was acted on like alcyonium asbestinum. The calcareous pant was soon dissolved ; but the form of the alcyonium remained unchanged, and still appeared like a pale yellow porous substance, enveloped by a skin or epidermis. Ammonia did not disturb the transparency of the solution ; but carbonate of lime was obtained by solution of potash. — When exposed to a low red heat, it re- sembled alcyonium asbestinum ; and a solution being subsequently made, afforded some phosphate of lime, with a large portion of carbonate. As this phosphate had not been discovered in the first experiment, and therefore appeared to have been defended from the action of the acid by the membranaceous part, that ex- periment was repeated, with this difference, that the acid was made to boil. A 720 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. complete solution of the whole was thus made, which, like that of the burnt alcy- onium, yielded phosphate of lime; and at the same time the liquor became of an orange colour, as soon as the ammonia was added. Some pieces of this alcyonium were digested with boiling distilled water, and tinged it with a pale yellow colour. Infusion of oak bark being then added, a large quantity of gelatin was precipi- tated. The same pieces were boiled with lixivium of caustic potash, and when dissolved formed animal soap. The calcareous part was separated during the boiling, and subsided in the form of a fine powder. From the examination of the few species of alcyonium which have been mentioned, it appears, that as the sponges resemble the horny stems of gorgoniae, so these, in external and chemical characters, resemble the fleshy or cortical substance which invests some of those bodies ; and that they chiefly differ from the gorgoniae, by being destitute of the horny stem, which in the latter seems to supply the place of bone. § II. Observations on the foregoing Experiments. The simplicity and uniformity of the experiments here described, will not, I flatter myself, render the facts less worthy of attention ; and I must repeat, that the minutiae of analysis did not form part of my present plan, which was only to sketch an outline, comprehending the most prominent chemical characteristics of certain bodies appertaining to the animal kingdom, which hitherto had been but little or not at all examined ; so that this outline, though defective, might serve as a chain of connection, and as a basis, on which a more perfect superstructure may in future be gradually raised ; and it appeared evident, that this would be most easily and speedily executed, by following a systematical and comparative plan. For this reason, a great part of my attention was directed towards ascer- taining, in these animal substances, the presence and general proportions of car- bonate and phosphate of lime ; these being the materials essentially employed by nature to communicate rigidity and hardness to certain parts of animals, such as shell and bone ; and though some other substances, as magnesia, silex, iron, with some alkaline and neutral salts, might be occasionally present in small proportions, and indeed were at times detected, yet, as these appear to have but little influence on the general characters of the bodies examined, I did not, for the present, think proper to take particular notice of them. The next object was, to examine the nature of the substance in and upon which the hardening or ossifying principles were secreted and deposited; and it seemed that the best mode of doing this, was to compare and examine this substance in the various states in which it appeared, when deprived of the hardening or ossifying matter. From what was said in the paper on shell and bone, concerning the substance which remained after the carbonate of lime in shells, and after the phosphate of lime in bones, had been dissolved and separated by weak acids, it is evident that the substance which thus remains, is as various in relative quantity, as it is in those qualities which apparently are produced by the degrees of natural inspissa- tion, and by the progressive effects of organization. In the porcellaneous shells, VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 7*21 such as cypreae, &c. this substance was proved to be much less in quantity than in those which were afterwards mentioned ; and though of a quality which, like a cement or gluten, served to bind and connect the particles of carbonate Of lime firmly together, so small was the degree of natural inspissation, and so little ad- vanced was the degree of organization, that when the carbonate of lime was dis- solved, even by very feeble acids, little or no vestige of jelly, membrane, or cartilage, could be perceived ; nor indeed could any be detected, but by the small portion of animal coal which was formed, when these shells had been exposed for a short time to a low red heat. But, proceeding from shells of this description to others tending to the nature of nacre or mother of pearl, such as some of the patellae, a substance was left untouched by the acids, which had the appearance of a yellowish transparent jelly*. So that the substance which served merely as a gluten in the porcellaneous shells, was not only more abundant in these patellae, but, being more inspissated, was become immediately visible and palpable. In the common oyster, these qua-> lities were more strongly marked ; and in the river muscle, and in the shells com- posed of the true nacre or mother of pearl, this substance was found not only to constitute a large part of the shell, but even to be more dense, so as no longer to appear gelatinous ; and in addition to these, strong and visible marks of organi- zation were stamped on every part, and a perfect membranaceous body remained, composed of fibres arranged parallel to each other, according to the configuration of the shells. From these facts, proved by the examination of only a very few, comparatively speaking, of the known shells, it appears that the hardening prin- ciple, or carbonate of lime, together with a substance varying from a very atte- nuated gluten to a tough jelly, and from this to a perfectly organized membrane, concur to form the matter of shell ; and, from the result of the experiments, and from all circumstances, there is every reason to believe, that the substance with which, or on which, the carbonate of lime is mixed or deposited, is of a similar nature, and differs only in relative quantity and density, arising from progressive changes, peculiar to the various species of shells, produced by certain degrees of natural inspissation, and by an organization more or less perfect. The experiments made on teeth, and on the bones of various animals, eluci- dated and confirmed the observations made on the nature of shell ; for, 1st. The enamel of teeth, in relation to the other bony substances, was proved to be as the porcellaneous shells are to those formed of mother of pearl ; the cementing substance of the enamel being a gluten, in the same state, and apparently of a similar nature, with that of the porcellaneous shells. And, 2dly. In certain bones, particularly those of fish, such as some of the bones of the skate, the substance which remained after the solution of the phosphate of lime, was of a gelatinous consistency, and exhibited but very imperfect traces of organization; by the others * The term jelly is here employed only to denote the degree of consistency of this substance, which m its nature is very different from the varieties of animal jelly called gelatin. — Orig. VOL. XVIII. 4 Z 12'L PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. however, a completely formed membrane or cartilage was left, retaining the figure of the original bone. When therefore the component parts of shell and bone are considered, it ap- pears that the essential characteristics are, carbonate of lime for the one, and phosphate of lime for the other ; and that their bases consist of the modifications of a glutinous, gelatinous, or membranaceous substance. I experienced much gratification in tracing the progressive and connected changes in the composition of the various shells and bones; and a considerable increase of pleasure arose, in proportion as the observations made on those bodies were corroborated, and the chain of connection extended, by the developement of the facts resulting from the experiments on zoophytes, which form the principal subject of this paper. It will now be proper to review these experiments, and to examine how far they agree with those made on shell and bone, and how far they tend to prove, that these substances are all of a nature closely connected. The experiments on the madrepores afforded the following results. Madrepora virginea, when examined by acids, left but very little of any gelatinous substance or membrane. M. muri- cata, and M. labyrinthica, afforded loose portions of a transparent gelatinous sub- stance. M. ramea, and M. fascicularis, when deprived of the carbonate of lime by acids, remained in the state of completely organized membranaceous bodies, which exhibited the original figure of the respective madrepores ; and the propor- tion of coal afforded by these last, was more abundant than what was obtained from those which were first mentioned. To these succeeded the experiments on the miliepores ; from which it appeared, that millepora caerulea afforded loose detached portions of a gelatinous substance. M. alcicornis yielded the same, but in a more coherent state. M. polymorpha remained unchanged in shape, and consisted of a strong white opaque membrane, filled with a transparent jelly. Lastly, M. cellulosa, M. fascialis, and M. truncata afforded membranaceous bodies, in a complete state of organization ; and all these miliepores, when exposed to a low red heat, yielded various quantities of coal, according to the greater or less abundance of the gelatinous or membranaceous substance. The universal, and only hardening principle of these madrepores and miliepores, was proved to be carbonate of lime, with the single exception of millepora poly- morpha, which also appears to be differently constructed from the other millepora?. With this single exception, carbonate of lime seems to be the only hardening sub- stance in these bodies ; and when every circumstance is considered, an exact simi- larity is to be found between the substance forming the various shells, and that which forms the madrepora? and milleporae ; and the nature of these bodies is so completely the same, that the changes or gradations of the one are to be found in the other. For the chemical characters which distinguish the porcellaneous shells, are in a great measure approached by those of madrepora virginea ; and those which were noticed in the patellae, correspond precisely with the madrepores and VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 723 millepores which afford a gelatinous substance ; and lastly, the characters of the membranaceous part, exhibited by the shells formed of nacre or mother of pearl, are in like manner to be found among some of the madrepores and millepores, such as madrepora ramea, millepora fascialis, millepora truncata ; for these, like the turbo olearius and haliotis iris, are composed of a fibrous membrane, hardened by carbonate of lime. It appears therefore, that the madrepores and millepores, like the various shells, are formed of a gelatinous or membranaceous substance, hardened by carbonate of lime ; and the only difference is in the mode according to which thest. materials have been employed. The experiments on tubipora musica proved, that in composition it resembled the foregoing substances. But a slight difference was observed, in respect to the hardening substance of flustra foliacea and corallina opuntia ; for a small portion of phosphate was found mixed with the carbonate of lime ; but the membrana- ceous part of these bodies resembled that of certain madrepores and millepores, particularly millepora fascialis. Two species of isis were next examined, namely, isis ochracea and isis hippuris : both of these were proved to be formed of regularly organised membranaceous, cartilaginous, and horny substances, hardened, in the last mentioned species, merely by carbonate of lime ; but, in the isis ochracea, with the addition of a very small portion of phosphate of lime. The subsequent experiments were made on various species of gorgonia, and first on gorgonia nobilis, which was formerly regarded as an isis. The hardening sub- stance of this was found to be carbonate of lime, with a small portion of* phosphate ; but the matter forming the membranaceous part was, like that of millepora poly- morpha, in 2 states ; that of the interior being gelatinous ; and that of the exter- nal part being a membrane completely formed, so as to cover the stem, in the manner of a tube. The results of the experiments on certain gorgoniae, such as ceratophyta, flabellum, suberosa, pectinata, and setosa, were not a little remark- able ; for, " when the 2 parts which compose these gorgoniae, namely, the horny stem, and the cortical substance by which it is coated, were separately examined, it was proved, 1st. That the stems of these gorgoniae consist of a substance analo- gous to horn ; and that, by long maceration in diluted nitric acid, this horny sub- stance becomes soft and transparent, so as to resemble a cartilaginous or tendinous body ; also the stems of these gorgoniae afford a quantity of phosphate of lime, but scarcely any trace of carbonate. 2dly. That the cortical part, on the contrary, consists principally of carbonate of lime, with very little or none of the phosphate; and the carbonate of lime is deposited in and upon a soft flexible membranaceous substance, which seems much to approach the nature of cuticle. Some other gorgoniae, which were subsequently examined, and which much resembled the former construction, did not yield any phosphate of lime ; but in every other particular they proved to be similar. The gorgonia antipathes was found to be entirely formed of a fibrous membrane; and the black shining polished gorgonia afforded, by maceration, a most beautiful specimen of membranes con- 4 z 2 724 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. centrically arranged. Lastly, the gorgonia which I have described as very much resembling the gorgonia antipathes, proved to be similar to that species, as to the membranaceous part ; but so large a portion of phosphate of lime was mixed with it, as almost to approach it to the nature of stag's or buck's horn ; there is there- fore great reason to consider it as a different species. The antipathes, which were next examined, were found to be little if at all different from the horny stems of the gorgoniae. And the various sponges, which were afterwards subjected to experiment, were proved to be completely formed by the same membranaceous or horny substance, which became varied by the modifi- cations of a more delicate construction, rather than by any essential difference in composition. This series of experiments terminated with an examination of a few species of alcyonium, namely, asbestinum, ficus, and arboreum ; all of which were found to be composed of a soft, flexible, membranaceous substance, very similar to the cortical part of some of the gorgoniae, such as gorgonia suberosa, and in like manner slightly hardened by carbonate, mixed with a small portion of phosphate of lime. From what has been said, there is reason to conclude, that the varieties of bone, shell, coral, and the numerous tribe of zoophytes with which the last are con- nected, only differ in composition by the nature and quantity of the hardening or ossifying principle, and by the state of the substance with which it is mixed, or connected. For the gluten or jelly which cements the particles of carbonate or phosphate of lime, and the membrane, cartilage, or horny substance, which serves as a basis, in and on which the ossifying matter is secreted and deposited, seem to be only modifications of the same substance, which progressively gradu- ates, from a viscid liquid or gluten, into that gelatinous substance which has so often been noticed, and which again, by increased inspissation, and by the various and more or less perfect degrees of organic arrangement, forms the varieties of membrane, cartilage, and horn. I shall now attempt to prove what I have here asserted, or at least assign the reasons which induce me to adopt this opinion ; but, in so doing, I am compelled, from the close connection of the subject, to anticipate the general result of part of a series of experiments, made with a view to investigate the nature and composition of membrane. . To enter into a minute detail of these experiments, would far exceed the limits of a paper like the present ; I shall therefore only mention, in a concise manner, the results of those which the subject immediately requires to be brought forward*. The method which first presents itself in such an investigation, is, the comparative analysis of the different substances, so that their relative proportions of carbon, hydrogen, and azote, should be precisely determined ; but when it is recollected how long a time would be requisite for making such an immense series of analyses, and how much animal substances are subject to be modified by situation in the * These are the experiments to which I alluded in my former paper, and which I began at the request of my friend Mr. Home, soon after the experiments on the enamel of teeth, &c. — Orig. VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 725 body, by age, and by the degree of health of animals, and also that the nature of these, and even that of the unorganised bodies, does not always merely depend on the proportion of the constituent principles, but also on the degree and mode of combination to which these principles are subjected ; I say that when all this, and the plan of the present paper, are considered, I natter myself that I shall not be censured as hasty or negligent, if at this time I prefer a comparison of the chemical properties of the bodies in question, with those of other substances which, though not elementary, may be regarded as primary animal compounds ; and when the subject is viewed in its full extent, the mode which I have adopted will perhaps be deemed that which is the most satisfactory. ^ III. Observations on the Component Parts of Membrane. In relating the preceding experiments, 1 have had frequent occasion to remark, that a quantity of that animal jelly which is more or less soluble in water, and which is distinguished by the name of gelatin, was obtained from many of the marine bodies, such as the sponges, the gorgoniae, and others ; but in the experi- ments made expressly to investigate the composition of membrane, it still more frequently occurred ; and though in many cases, either from the small quantity of the body under examination, or from the very small portion of gelatin thus obtained, I was obliged to content myself with ascertaining the presence of it, by the test of the tanning principle, and by nitro-muriate of tin;* yet in other experiments, when the solutions of gelatin were gradually reduced by evaporation, I had opportunities of frequently observing the various degrees of viscidity and tenacity which characterize mucilage, size-)~, and glue. The difference in the viscidity and tenacity of the varieties of these substances, is evidently an inherent quality, and not caused by the degree of mere inspissation : if this was the case, mucilage, size, and glue, when dry, would be of an equal quality, which is how- ever contrary to daily experience ; for the varieties of glue are not of equal tena- city. And it is well known, that glue made from certain parts of animals, such as the skin, is more tenacious, and of a better quality, than that which is made in some places from feet and sinews. Also, when even the same part is employed, which has been taken from 2 animals of the same species, an evident difference is found, according to the com- parative age of the animals ; for the best and strongest glue is always obtained from the more aged animals, in whom the fibre is found to be the most coarse and strong. But a longer continued boiling appears requisite in order to extract it ; and the more viscid glues are obtained, from the substances which afford * Nitro-muriate of tin has been proposed as a test for the tanning principle ; and the experiments contained in this paper prove, that it may also be employed with much utility, to ascertain the pre- sence of gelatin, and of certain modifications of albumen. \ The term size is employed, throughout this paper, to denote that modification of gelatin which appears to be intermediate, between mucilage and the most viscid and tenacious gelatinous substances or glues. The weaker kinds of glue may therefore come under this denomination. — Orig. 726 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. them, with greater difficulty than those of a less viscid quality, which may more properly be called size: this difference is to be observed, when muscle is boiled with repeated and frequent changes of water. Gelatin thus obtained, whether in the state of mucilage, size, or glue, when completely dried,- is affected by water according to its degree of viscidity : for, when cold water is poured on dry muci- lage, it dissolves it in a short time ; but if cold water be poured on those varieties of gelatin which, when dissolved in a proper quantity of boiling water, would, by cooling, form jellies more or less stiff", it acts on them in different degrees, not so much by forming a complete solution, as by causing them to swell and become soft ; so that, when a cake of glue has been steeped 3 or 4 days in cold water, if it swells much without being dissolved, and, when taken out, recovers its original figure and hardness, by drying, such glue is considered to be of the best quality. I shall soon have occasion to notice, in another place, the effects of acids and of alkalies on gelatin ; it will therefore here be sufficient to observe, that as it is soluble in acids, so, if dry mucilage, dry size*, and dry glue, be steeped in nitric acid diluted with 3 or 4 parts of water, they will be progressively dissolved, according to the degree of viscidity by which they are separately distinguished. When the solutions of these substances in water were examined by the tanning principle, and by nitro-muriate of tin, I have found that animal mucilage is more immediately affected by the latter than by the former ; while the solutions of size and of glue are equally acted on by both. And when gold dissolved in nitro- muriatic acid was added to the solutions of mucilage, size, and glue, the gold was reduced to the metallic state in a few hours, not only on the surface, where it formed a shining metallic pellicle, but also on the sides of the glass, which were thinly coated with a deep yellow sediment, which, like leaf-gold, appeared of a fine pale green, when held between the eye and the light. The animal mucilage which I chiefly employed in these experiments, was ob- tained from the corallina officinalis, as I found it to be pure, and not partly modi- fied into gelatin or animal jelly-}-. But Mr. Bouvier asserts, that he obtained the latter substance^ ; and this appears to me very probable ; for mucilage may pre- dominate in this coralline at one period, and gelatin or jelly at another, just as it is found to be the case with other animal substances ; for it is known, that in young animals mucilage is abundant, and becomes diminished as these increase in growth and age. Hence there is every reason to conclude, that the substance which in very young animals was at first mucilaginous, becomes progressively * Gelatin obtained from eel-skin, evaporated to dryness. f By this I mean, that the mucilage had not acquired the degree of viscidity requisite to form a gelatinous substance. The expression which I have employed, is not therefore to be understood as alluding to any essential difference in composition, but only to denote some variation in the degree of consistency; for the whole may be comprehended under the term gelatin, of which, mucilage may be regarded as one extreme, and the strongest and most viscid glue as the other. 1 Annales de Chimie. torn. 8» p. 311.— Orig. VOL XC.] PHILOSOPHICAL TRANSACTIONS. 727 more viscid, and assumes the characters of gelatin ; which, as animals increase in age, is known to become more and more viscid, as has been already mentioned in the foregoing pages. I am inclined therefore to consider mucilage as the most attenuated, and as the lowest in order, among the modifications of gelatin. As the qualities of gelatin are so various, so the properties of the substances in which it is present as a component part, are much influenced by it ; and when, for example, the skins of different animals were compared, I have always found that the most flexible skins afforded gelatin more easily, and of a less viscid qua- lity, than those which were less flexible, and of a more horny consistency. The skin of the eel possesses great flexibility ; and it affords gelatin very readily, and in a large proportion. The skin of the shark also, which is commonly used by cabinet-makers to polish their work, was in like manner, for the greater part, soon dissolved, and formed a jelly, like the former. The epidermis or cuticle of these skins, which is very thin and tender, though not soluble, was reduced into small particles by violent ebullition, and the spicula on the shark's skin were also sepa- rated. The skins of the hare, rabbit, calf, ox, and rhinoceros, were examined in a similar manner, and with the like results ; but the gelatin obtained from the hide of the rhinoceros, as far as the smallness of the piece of skin would allow me to determine, appeared to be the strongest and most viscid. In every one of these experiments, the true skin or cutis was principally affected, it being com- pletely soluble, as Messrs. Chaptal and Seguin have well observed, by long boiling; but that of the rhinoceros far exceeded the others in difficult solubility. The cutis of these skins, when first boiled, swelled and appeared horny ; it was then gradually dissolved ; but in the cutis of the rhinoceros a few small filaments remained, which at length contracted and adhered to the cuticle. The cuticle of the different skins was softened, but not dissolved ; and, as the cutis seems to be essentially formed of gelatin,* so the cuticle appears to contain it, though but in a small proportion : it is however necessary to its flexibility ; for when, after long boiling, the cuticle of these skins was dried, it became a brittle substance, which was easily reduced to a powder. Hair was much less affected than either of the above-mentioned substances ; and this, with others in some measure similar, I shall now more particularly notice. The substances to which I allude, are hair, feather, horn, horny scale, hoof, nail, and the horn-like crust which covers some insects and other animals, such as the scorpion and the tor- toise. These I shall now mention, in as concise a manner as the subject will allow. When hair of various qualities, and taken from different animals, was long digested or boiled with distilled water, it imparted to the water a small por- tion of gelatin, which was precipitated by the tanning principle, and by nitro- muriate of tin ; and when the hair had been thus deprived of gelatin, and was subsequently dried in the air, the original flexibility and elasticity of it were found * The cartilages of the articulations are also completely soluble when Jong boiled with water; but this by no means happens when other cartilages are thus treated. — Orig. 728 PHILOSOPHICAL TRANSACTIONS. [ANNO ] 800* to be much diminished, so that it easily gave way, and was broken. This effect, Mr. Achard has also noticed ; * and I am induced to believe, from various experi- ments which I have made on these substances, that the hair which loses its curl in moist weather, and which is the softest and most flexible, is that which most readily yields gelatin ; and, on the contrary, the hair which is very strong and elastic, is that which affords it with the greatest difficulty, and in the smallest pro* portion. These remarks have also been corroborated, by the assertion of a conr siderable hair merchant in this metropolis j-, who, during a long experience of upwards of 40 years, has always found, that hair of the first named quality cannot be boiled an equal time with those last mentioned, without suffering material in- jury in strength and flexibility. Feather, digested in boiling distilled water, during 10 or 12 days, did not afford any trace of gelatin by the test of the tanning principle; but nitro-muriate of tin produced a faint white cloud. The same was observed when quill was thus examined. Shavings and pieces of the horns of different animals were next sub- jected to experiment, and all afforded small quantities of gelatin, which was pre- cipitated by the tanning principle, and by nitro-muriate of tin ; and it was gene- rally observed, that the more flexible horns yielded the largest quantity of gelatin, with the greatest ease ; and, like the substances already mentioned, when deprived of it, and suffered to dry spontaneously in the air, they became more rigid, and were easily broken. The horns which I mean, are those of the ox, ram, goat, and chamois, which, in my former paper I considered, as I do now, to be per- fectly distinct from the nature of stag's or buck's horn ; for this last is as different from the former in chemical composition, as it is in construction : like bone, it affords much phosphate of lime, and, like bone, it affords a large quantity of gelatin ; and it is not a little remarkable, that phosphate of lime is generally ac- companied by gelatin, as in stag's horn, bone, ivory, &c. on the contrary, when carbonate of lime is the hardening substance, as in shells, madrepores, and mil- lepores, no gelatin can be discovered ; for I have frequently digested these sub- stances many days in boiling distilled water, after having reduced them to a coarse powder that they might present a larger surface, but I never could by any test discover the slightest vestige of gelatin. The horns therefore which were first mentioned, are very different from the composition of stag's horn, and yield gra- dually, and with great difficulty, only a small quantity of gelatin. Horny scale was next examined ; but I shall first here make a digression in respect to the scales of fish, which I had not examined when my paper on shell and bone was read. As the scales of fish, when viewed by a microscope, and according to the observations of Mr. Leeuwenhoek, appear to be formed of dif- * " La perte de la partie gelatineuse otant aux cheveux leur souplesse, il s'ensuit que c'est aux " parties gelatineuses qui entrent dans la composition des cheveux qu'ils doivent leur pliant et leur elas- " ticite." — Examen chimique des Cheveux, &c. Mem. de l'Acad. de Berlin, torn. 38. p. 12. f John Collide, Esq. of St. Martin's-lane. — Orig. VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 720 ferent membranaceous laminae, and as they exhibit the colour and lustre of mother of pearl, it might be expected, that they should prove to be of a similar nature with the substance of stratified shells, or in other terms, that they should consist of membrane and carbonate of lime. But when scales perfectly clean, and sepa- rated from the skin of different fish, such as the salmon and carp, had been im- mersed during 4 or 5 hours in diluted nitric acid, till they became transparent, and perfectly membranaceous ; the acid liquor, being then saturated with pure ammonia, afforded a copious precipitate, which was proved to be phosphate of lime. The spiculae of the shark's skin, formerly mentioned, were found to be of a similar composition ; and we may therefore regard the spicula and scales of fish as true bony substances, in which the membranaceous part is more predominant than in common bone. I fully ascertained, that the phosphate of lime was afforded by these substances only ; for when the different skins from which these scales and spicula had been taken, were separately examined in the like manner, no phosphate of lime was obtained. In addition to this I must observe, that the silver or pearly hue of pearl, mother of pearl, and of fish-scales, is only assisted and modified by the relative degrees of opacity produced, in mother of pearl and in pearl, by the interposition of the particles of carbonate of lime, and in the scales by phosphate of lime; for this peculiar lustre principally resides in the mem- branaceous part, and remains with it when the acetous or muriatic acids are em- ployed as menstrua, but is completely destroyed by the nitric acid. The horny scales of serpents, lizards, and such like animals, differ from the foregoing ; as all of those which I have examined, consist merely of the mem- branaceous or horny substance, in a more or less indurated state, and appear to be devoid of phosphate of lime, as an ossifying matter. Horny scales in general, and the scales of the manis pentadactyla may be mentioned as an example, afford but very slight traces of gelatin after being long boiled in distilled water ; and this small portion of gelatin can only be discovered by the tanning principle, and by nitro-muriate of tin, unless a very large quantity of the scales has been employed. Human nail digested in boiling distilled water during several days, was only soft- ened ; and, like quill, afforded a slight cloud, by the addition of nitro-muriate of tin. Shavings of ox's hoof, when long digested as above-mentioned, afforded a liquor which, in like manner, was only made slightly turbid by nitro-muriate of tin. Nail and hoof, when long boiled, became of a much darker colour. The horn-like crust which covers certain insects and other animals, was sub- sequently examined; the experiments were principally made on the plates which covered the body of a large African scorpion, and on the common tortoise-shell of the shops. The plates taken from the scorpion were not apparently affected, though digested for a long time in boiling distilled water. The tanning principle produced no alteration, when added to the water; but a faint white cloud appeared, on the addition of nitro-muriate of tin. Tortoise-shell, in thin slips, and shavings, was digested in a similar manner during 3 weeks; but it was only slightly softened VOL. XVIII. 5 A 730 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. and the water, which had acquired a brownish colour, was but little affected, even by nitro-muriate of tin, which however formed a white cloud*. From some previous circumstances, which need not here be mentioned, I was lastly induced to make some similar experiments on albumen; and as that of the blood is mixed with gelatin, and with the substance called fibrin by the chemists, which in chemical properties appears to be the same as muscular fibre, and as it is with some difficulty that the albumen can be exactly separated from these substances, I preferred the albumen of eggs, as being pure and unmixed ; and, in order that it might be brought into a state in some measure similar to the bodies lately ex- amined, by which I mean simple inspissation, I dried it, after coagulation, in a vessel which was heated to 212° of Fahrenheit, till it became perfectly hard, brittle, yellow, and semi-transparent, like horn. The albumen, in this state, was digested 8 days in boiling distilled water, which was occasionally renewed, in proportion to the evaporation. In a few hours after the commencement of the digestion, the transparent horny pieces of albumen were softened, and became white and opaque, exactly like albumen recently coagulated; but, after this, no further change was observed. At the end of 8 days, the water in which the albumen had been digested was examined, and was found exactly to resemble that afforded by quill, nail, and tortoise-shell; for the transparency of it was not disturbed by the tanning principle, though nitro-muriate of tin produced a faint white cloud -j~. As far therefore as could be ascertained, by long digestion in boiling distilled water, and by the effects of the re-agents, albumen was proved to be very similar to tortoise- shell, and many of the other substances previously noticed; but the close re- semblance, or rather indeed identity, of albumen with those bodies, will be placed in a stronger light, by the enumeration and comparison of their other chemical properties. As I have, in the former part of this paper, had occasion to mention the gelatin obtained from the sponges and gorgonize, it is not necessary here to repeat those remarks, neither is it requisite that I should enter into any minute account concerning the experiments made on bladder, and some other membranes. It may therefore suffice here to observe, that all these bodies afforded more or less gelatin ; that when this was separated, the remaining substance ceased to be tough, or elastic, and was easily torn, like wetted paper; and that when dry, the sponges, and such membranes as bladder and cuticle, became very brittle, and were shrivel- led and curled up, like withered leaves of plants. But, before speaking of the nature of the substance which thus remained, it will be proper, concisely to notice the effects of acids on the bodies which afford * The crust which covers insects like the scorpion, appears in every respect to be similar to tortoise- shell. f When infusion of oak-bark is added to recent liquid albumen, it immediately forms a precipitate) and nitro-muriate of tin does not produce an effect till some hours have elapsed. But after coagulation the reverse takes place; for the water in which coagulated albumen has been long boiled, becomes turbid by the addition of nitro-muriate of tin j and is not in any manner affected by infusion of bark. — Orig. VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 731 gelatin; and as the most remarkable effects were produced by nitric acid, I shall to that confine the present observations. The specific gravity of the nitric acid which I employed in the whole of my experiments, was 1.38; and this acid was diluted with 2, 3, or 4 measures of distilled water, according to the quality of the substance under examination, and the intended time of immersion. But as an acid too powerful would have frustrated my intentions, I commonly added the acid, by degrees, and at long intervals, to the water in which the substance was im- mersed; during which time if any nitrous gas was discharged, more water was added, as this gas was a certain sign that the acid was not sufficiently diluted. Substances like the corallina officinalis, which contain a large quantity of animal mucilage, or of the least viscid jelly, soon impart it to boiling water. In like manner, when such substances were steeped in nitric acid diluted with about 3 measures of water, the mucilage was in a few hours completely dissolved, while the membranaceous part remained untouched. Pure isinglass dissolved in the di- lute nitric acid, formed a pale yellow liquor, which by evaporation became of a deeper colour, and when nearly dry was suddenly reduced to a spongy coal. This change was rapid; and was attended with a considerable effervescence, and a copious discharge of nitrous gas, not unfrequently accompanied by sparks, and sometimes flame; arising undoubtedly from nitrate of ammonia, which was formed towards the end of the evaporation. The acid solutions of mucilage, isinglass, and pure glue, were changed to a deeper yellow, when saturated by the absorbent earths, by the alkalies, and epecially by pure ammonia. In such cases, little or no precipitate was obtained from pure gelatinous substances; but some faint traces of phosphoric acid were discovered in these solutions. The effects of the dilute nitric acid on the other various substances which have been mentioned, resembled those now described, and kept pace exactly with those of boiling water; for when they were immersed in equal quantities of the dilute acid during a given time, the solution of the gelatin took place according to the order observed in those substances, when water was employed. As an instance of this, 2 pieces of skin, recently taken from an ox, were subjected to experiment, as follows: one of the pieces was boiled in water, till the whole of the cutis was dis- solved; after which, the cuticle remained, though very feeble in texture, while the hair did not seem to have suffered any material alteration. The other piece was steeped in nitric acid diluted with about 4 measures of distilled water. At the end of 5 days the cutis was dissolved, and the cuticle was become of a loose and feeble texture; but the hair had not suffered any apparent change, except that of being slightly tinged with yellow. In both cases therefore the effects of boiling water and of acid were similar, and were evidently most powerful on those parts which were the most gelatinous. As water dissolves mucilage more speedily than size, and this last more readily than strong viscid glue, so are the effects of very dilute nitric acid on the same substances; and when equal quantities of dried mucilage, of eel-skin glue, and of 5 A 2 732 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. the strongest glue, were dissolved in equal quantities of the dilute acid, the colour of the solutions was more intense, and the change produced by amnaonia was more visible, according to the order of solubility and of tenacity. It is well known how readily gelatin is dissolved by the caustic fixed alkalies: when therefore the varieties of jelly or glue were added to boiling lixivium of caustic potash, they were soon dissolved; and when added to saturation, a brownish viscid substance was formed. I did not observe that any ammonia was produced, neither was any coal deposited, after long boiling the solution in which there was an excess of alkali. The viscid matter thus obtained, did not possess the properties of animal soap; for it neither formed a permanent lather, when mixed and shaken with water; nor, when satu- rated with acids, did it afford any precipitate; contrary to what happens, when animal soap is thus treated. But, when the gelatinous substance was not pure; if, for example, any parts of membrane, which are not soluble in water, were present, then, in proportion to the quantity of this substance, the alkaline solution exhibited more or less of the saponaceous characters; but these I never observed when pure gelatin was employed. Gelatin, according to its quantity and quality, has a powerful influence on some of the physical and chemical properties of the bodies in which it is present; by these properties, I mean flexibility, elasticity, and putrescibility. So much has been said already, in various parts of this paper, tending to prove how much the degrees of flexibility and elasticity, in various animal substances, depend on their gelatinous part, that little need be added; and when it is considered that bodies, such as muscular fibre, membrane, sponge, hair, and cuticle, being deprived of gelatin, and dried in the air, become rigid and brittle, no doubt can be entertained but that this arises from the loss of the gelatinous substance; and, as an additional proof, when bodies, such as nail, feather, quill, and tortoise-shell, which contain little or no gelatin, are long boiled, and then dried in the air, like the former, they are found to have suffered scarcely any alteration in their respective degrees of flexibility and elasticity. As to putrefaction, it is obvious to every one, that certain parts of animals are much more susceptible of it than others; and that when the carcase of an animal begins to putrefy, the most humid and flexible parts are always first affected. Thus, the viscera, muscles, and cutis, soon suffer a change ; while hair, feather, scale, horn, hoof, and nail, remain unchanged, ages after the former have been decom- posed ; and this is evidently caused by the gelatin and moisture, which are com- bined in the former, and not in the latter, at least in any notable quantity. I have already mentioned the progressive and comparative effects of boiling water, and of dilute nitric acid, on the skin of the ox; and I have showed, that while the cutis was completely dissolved, the hair remained untouched. These effects are to be observed, in the same exact order, when a similar piece of skin is exposed to putrefaction; for this commences in, and chiefly affects, the cutis, while the hair is separated, unchanged in its quality. I do not therefore hesitate to assert, VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 733 that the degree of putrescibility in the various parts of animals, depends principally on the presence, and on the quantity and quality, of gelatin; and the skin of the rhinoceros found on the banks of the Vilui, near Yakutsk, was preserved, in all probability, partly by the nature of the climate and soil, and partly by the superior horny quality which it possessed over other skins; for it may be much questioned, whether the hide of an ox or horse, in the same situation, would have escaped putrefaction for so long a period*. From the preceding observations it appears, that gelatin is a component part of many animal substances. That it differs in quality, from a very attenuated jelly or mucilage, to that viscid substance called glue; the varieties of which also differ in solubility and tenacity. That it is present in various proportions; so that certain bodies, such as the cutis, and the cartilages of the joints, are formed by it; while others, like nail, quill, and tortoise-shell, can scarcely be said to contain it. And that, by its presence, in various states and proportions, it may be regarded, in- cluding inherent moisture and organic arrangement, as the principal cause of those degrees of flexibility, of elasticity, and of putrescibility, so various in the different parts of animals-}-. But, when gelatin has been separated from the different sub- stances, either by repeated boiling with water, or by being steeped in dilute acids, a more insoluble substance remains, of a very different nature, which I shall now proceed to examine. When a bone or piece of ivory has, by long boiling in water, been deprived of a great part of its gelatin, and is afterwards steeped in a dilute acid, the ossifying substance is dissolved, and the cartilage remains, retaining the figure of the original bone; or, if a similar bone or piece of ivory, which has not * The more viscid gelatinous substances do not appear to be so immediately susceptible of putre- faction as those of the opposite quality j for, when solutions in water of animal mucilage, eel-skin glue, and strong glue, were during a certain time exposed under equal circumstances, I found the mu- cilage to be the first, and the glue the last, which showed symptoms of putrefaction. f As gelatin, according to its proportion and quality, appears to produce considerable effects on the parts of animals in which it is present: and, as the gelatin in animal bodies is, in all probability, liable to be changed and modified by morbid causes, it is much to be wished, that gentlemen of the medical profession would ascertain, by experiments, how far the tonic properties of barks depend on the tanning*principle. Mr. Biggin has proved, (Phil. Trans, for 1799, p. 259,) that willow bark, and especially that of the Huntingdon or Leicester willow, contains the tanning matter in a considerable quantity ; and that the latter, in this respect, even equals, or rather exceeds, that of oak. My friend, the Rev. Thomas Rackett, Rector of Spetisbury and Charlton, in Dorsetshire, has employed, in these parishes, the bark of the common willow with great success, as a tonic and febrifuge. Also, Mr. Westring, of Norv- koping, has observed, (Annales de Chimie, torn. 32, p. 179>) that those species of cinchona which contain the tanning principle in the greatest quantity, are the most efficacious in fevers ; and that the cinchona floiibunda, which contains scarcely any tanning matter, is destitute of the above-mentioned beneficial effects. Mr. Westring therefore, with great apparent reason, believes that the relative effects produced by the different species of cinchona, when employed in medicine, are in proportion to their tanning power, or the quantity of tanning principle contained in them. If any one should be induced to make experiments on the tonic effects of the tanning principle, it is to be hoped that some attention would also be paid to the medicinal properties of nitro-muriate of tin, of which, at present, I believe little or nothing is known. — Orig. 734 PHILOSOPHICAL TRANSACTIONS. [ANNO ] 800. been boiled, is steeped in a dilute acid, (especially nitric acid,) the ossifying sub- stance is dissolved, and, at the same time, but more slowly, the gelatin is sepa- rated, and causes the liquor to become yellow, when the phosphate of lime is pre- cipitated by ammonia. The cartilaginous body which remains, after the gelatin has been thus separated, is not easily soluble in dilute acids, for, according to its texture, many weeks, and even months, may elapse, before a small part is taken up; but in concentrated nitric acid, or in boiling dilute acid, it is rapidly dissolved. This substance, when dry, is semi-transparent, like horn, and more or less brittle. It is the predominant and essential part, in the tissue or web of membrane, carti- lage, sponge, the horny stems of gorgoniae, horn, hair, feather, quill, hoof, nail, horny scale, crust, and tortoise-shell ; and, though of similar chemical properties, yet in consistency it varies, from a tender jelly-like substance, to a completely formed membrane, or to an elastic, brittle, and hard body, like tortoise-shell*. Experiments were made separately, on each of the bodies above enumerated; but as I did not find any essential difference in the results, I shall include the whole under the following observations. 1. When distilled, a small portion of water, some carbonate of ammonia, a foetid empyreumatic oil, carbonated hydro- gen gas, carbonic acid gas, and prussic acid, were obtained. 1. A spongy coal, of a gray metallic lustre, remained : this; by incineration, afforded a very small residuum, which was not always similar in quantity, even in portions of the same substance; for, 500 gr. of tortoise-shell, taken from different samples, afforded from -J- of a gr. to 3 gr. of residuum, which consisted of phosphate of lime, and phosphate of soda ; sometimes also a little carbonate of lime was present; but I do not believe these to be essential ingredients. 3. When boiled many days in distilled water, the substance was softened ; and the water became slightly turbid with nitro-muriate of tin; but no effect was produced by the tanning principle. 4. Muriatic and sulphuric acids had little effect, unless heated; and the same was the case with nitric acid much diluted, or in the state proper to extract and sepa- rate gelatin ; but if the immersion in the dilute acid was continued during some weeks, the acid gradually acquired a yellow tinge, and, when saturated with am- monia, became of a deeper colour, without having its transparency disturbed. 5. The substance which had thus been long steeped in the acid, was much softened, was become more transparent, and, from being horny, was now more like a car- tilaginous substance: when taken out of the acid, if it was immediately steeped in pure ammonia, it changed to a deep orange colour, inclining to blood red; it was gradually and silently dissolved, without any residuum, and a deep orange or yel- lowish brown coloured liquor was formed. • These bodies, especially tortoise-shell, appear to be formed, as far as organic arrangement is con- cerned, in the way of stratum super stratum. This structure is peculiarly to be discovered after long maceration in diluted nitric acid; for then, tortoise-shell appears to be composed, like the black polished gorgenia, of membranaceous laminae ; and the varieties of horn differ only by a tendency to the fibrous organization. — Orig. VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 735 6. Or, when taken out of the acid, if it was first well washed in distilled water, and then boiled, it was also dissolved, and formed a pale yellowish solution: this, by evaporation and cooling, became a jelly, which was again soluble in boiling water; and was precipitated, like gelatin, by the tanning principle and more slowly by nitro-muriate of tin. 7- If the nitric acid in which the substance was im- mersed was not sufficiently diluted, or if heat was applied, the whole was rapidly dissolved, with a considerable effervescence, and discharge of nitrous gas. 8. This solution was yellow, like the former, the colour being intense, in proportion to the quantity dissolved; and it was also changed to a deep orange or yellowish brown by the addition of ammonia, without depositing any precipitate, unless a large quantity had been dissolved. 9. The nitric solutions of this substance, when evaporated, afforded much the same appearances as those of gelatin, but the coal which remained was less spongy. 10. This substance, whether of sponge, horn, quill, hair, nail, or tortoise-shell, &c. was strongly distinguished from gelatin, by the effects produced when boiled with caustic fixed alkali ; for animal soaps were formed, exactly similar in every property excepting colour, and the whole of the original substance was completely dissolved. 11. During the process, a consider- able quantity of ammonia was discharged; and, if the alkali was in excess, some coal was deposited. 12. When the animal soap was dissolved, diluted with distilled water, and filtra- ted, if an acid, such as the acetous or muriatic, was added, a copious precipitate was obtained, which was re-dissolved by an excess of acid. 13. This precipitate, being collected on a filter, appeared at first like a yellow or brownish viscid sub- stance, which, when dry, was like a thick coat of varnish, or dried white of egg, and in like manner was brittle, and broke with a glossy fracture. 14. It burned like quill or tortoise-shell, leaving a spongy coal; and, when distilled, afforded products like those obtained from the bodies above-mentioned. 15. It was not readily soluble in dilute acids; and was acted on by nitric acid and ammonia, like the substances from which it had been obtained; the properties also of its solu- tions in nitric acid and ammonia were similar. 16. With caustic lixivium of pot- ash it readily combined, and again formed animal soap. 17- It was not quite so insoluble in boiling water as quill or tortoise-shell; and the water in which it had been boiled was not only made turbid by nitro-muriate of tin, but yielded a pre- cipitate when infusion of oak-bark was added, after the manner of gelatin. These experiments proved, that this precipitate was the same as the original substance from which it had been obtained; and that the only change it had suffered, was that of being rendered rather more soluble in boiling water. The whole series of experiments on the various bodies lately enu- merated, convinced me also, by the similarity of results, that they es- sentially consisted of one and the same substance, modified in texture by the degrees of organic arrangement and by the occasional presence, and different pro- 736 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. portion and quality, of gelatin. But the difference in chemical properties showed that this last mentioned substance, gelatin, was quite distinct from that which is now under examination; and, from the resemblance of certain effects observed when quill and tortoise-shell were compared with inspissated albumen, by being long digested in boiling water, I was induced to make a series of comparative ex- periments on albumen, similar in every respect to those which have been so lately described, of which the following are the results. ] . By distillation, the coagulated dry semi-transparent albumen, afforded products exactly similar to those obtained from tortoise-shell, and the other substances which have just been examined. 1. A spongy coal remained, of very difficult incineration; as towards the end of the process it appeared vitrified, and glazed with a melted saline coat, which was how- ever easily dissolved by water. The residuum was again exposed to a long con- tinued red heat, and again treated with water, till at length a few scarcely visible particles remained; which, as far as such a small quantity would permit to be as- certained, proved to be phosphate of lime. The portion dissolved by water, which was by much the most considerable, consisted principally of carbonate, mixed with a small quantity of phosphate of soda. 3. When steeped in dilute nitric acid, it was not soon affected ; but, after about 4 weeks, the acid began to be tinged with yellow, which gradually became deeper in the course of 3 months; the albumen however, though less transparent, was but little diminished. The yellow acid so- lution, when saturated with ammonia, changed to a deep orange colour, and re- mained transparent. 4. The albumen which had been thus steeped in the dilute nitric acid, was im- mediately immersed in ammonia ; which changed it to a deep olive colour, inclin- ing to a blood red, and gradually dissolved it, without any apparent residuum. This solution is of a deep yellowish brown. 5. If the albumen, instead of being immersed in ammonia, was washed, and then boiled with distilled water, it was dissolved, and formed a pale yellow liquor, which, by evaporation, formed a gelatinous mass ; this, being dissolved again in boiling water, was, like gelatin, precipitated by the tanning principle, and more slowly by nitro-muriate of tin. 6. By concentrated nitric acid, or by the dilute acid when heated, albumen was speedily dissolved, with much effervescence, and a copious discharge of nitrous gas. 7. This solution was like that of tortoise- shell, and the other substances mentioned in the former experiments. 8. When evaporated, it afforded similar results. 9. Albumen, like tortoise-shell, quill, and nail, was dissolved by boiling lixivium of caustic potash, and formed animal soap. 10. In like manner also, a considerable portion of ammonia was discharged ; and, if the alkali was in excess, some coal was deposited. 1 1 . The animal soap ob- tained from albumen, when dissolved in water, yielded a precipitate, by the addition of acetous or muriatic acid ; and the precipitate was re-dissolved when the acid was added to excess. VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 737 ] 2. This precipitate, when collected on a filter, appeared more saponaceous, and less viscid, than that obtained from the substances lately examined*. When gently heated, some oil flowed from it ; after which a brownish viscid substance re- mained, similar in its properties to that which was obtained from the animal soap made by tortoise-shell and the other bodies-f-. 13. It may not be improper here to repeat, that inspissated albumen, long boiled with distilled water, was not apparently diminished ; but the water, like that in which tortoise-shell, quill, or nail, has been boiled, had acquired the property of becoming white and turbid, when nitro-muriate of tin was added, though it was not changed by the tanning principle. To this also may be added, that the water in which tortoise-shell, nail, and albumen, had been boiled, became in some measure putrid in a few days, and emitted an offensive smell. I am not inclined however, to regard this as a proof that any gelatin had been separated from these bodies by means of boiling water, but rather that inspissated albumen, tortoise-shell, &c. are substances really soluble, though in so slight a degree as to approach insolubility ; and that thus the prevalent opinion has arisen concerning the insolubility of coagulated albumen in boiling water. Neither is the putrefaction of the water in which the bodies abovementioned have been boiled, a proof that any other than their real substance has been dissolved ; for this putre- faction appears to depend on its attenuated and diluted state, more than on any other cause. Tortoise-shell, nail, quill, and similar bodies, certainly are not liable to putrefaction ; neither is albumen, when in the inspissated semi-transparent state. This last substance also, when merely coagulated, does not easily putrefy ; for I kept it, when it was soft, white, and coagulated, in water, during the whole of the month of April, without finding that it became really putrid; towards the latter part of the time, it had rather a disagreeable smell ; still however it was far from being absolutely putrid. But albumen which has not been coagulated, or which has been diluted and shaken with a quantity of cold water, begins in a very few days to be putrid ; liquid albumen therefore enters easily into putrefaction, though it is the reverse with that which is dense and solid : and from a comparison of the preceding ex- periments on tortoise-shell, quill, nail, &c. with those made on albumen, I am induced to believe that the former bodies are essentially composed of albumen, modified by the various effects of organization, and reduced to a state of density far exceeding that which is produced by simple inspissation. And though the * This precipitate, when obtained from different substances, such as hair, wool, and muscular fibre, appeared in some cases more, and in others less viscid, though similar in every other property. It will be proper also to observe, that the saponaceous solutions were always filtrated, before the addition of the acids. f The yolk of eggs, when boiled with caustic lixivium of potash, forms a pale olive- coloured concrete animal soap, which, when dissolved in water, and saturated with muriatic acid, is precipitated in the state of mere fat. Yolk of egg, by incineration, affords a small portion of phosphate of soda and of lime. VOL. XVIII. 5 B 738 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. bodies, which of late have been particularly mentioned, appear to consist prin- cipally of albumen, with sometimes the addition of gelatin in different proportions, yet, as in certain membranes and such like substances, portions of muscular fibre were at times found joined or interwoven ; and as muscle, ligament, and tendon, seem to glide almost imperceptibly into each other, I was almost unavoidably in- duced to make some experiments on muscular fibre. The muscular fibre on which the greater part of these experiments was made, was that of beef; and in order to separate the liquid albuminous part or lymph as much as possible, a quantity of lean muscle of ox beef, cut into small thin pieces, was macerated 15 days in cold water, and was subjected to pressure each day, when the water was changed. The weather was very cold; and the maceration was continued to the end of the 15th day, without any sign of putrescency. The shreds of muscle, amounting to about 3 lb., were then boiled with about 6 quarts of water, during 5 hours ; and, the water being changed, the same was repeated every day, for 3 weeks ; at the end of which time, the water afforded only slight signs of gelatin, when infusion of oak-bark, or nitro-muriate of tin, was added. After this the fibrous part was well pressed, and was dried by the heat of a water bath. Some of the muscular fibre thus prepared, was steeped in nitric acid diluted with 3 measures of water, for 15 days. The acid acquired a yellow tinge, and possessed all the properties of the nitric solutions of albumen. The fibre which had been thus steeped in the acid, was, when washed, dissolved by boiling water, and by evaporation became a gelatinous mass: which, being again dissolved in boiling water, was precipitated by infusion of oak-bark, and, more slowly, by nitro-muriate of tin, like the albuminous substances, when treated in a similar manner. When the fibre which had been steeped in the acid was immersed in ammonia, it was not completely dissolved, like albumen, but afforded a residuum, which will soon be noticed. The greater part was, however thus dissolved ; and formed a deep orange or yellowish brown solution, similar in properties to that of albumen. When boiled with lixivium of caustic potash, this muscular fibre was completely dissolved ; ammonia was discharged, and animal soap was formed; which being diluted with water, and saturated with muriatic acid yielded a precipitate, similar in every property to that which had been obtained from the animal soaps formerly mentioned, excepting that it sooner became hard and glossy, when exposed to the air*. Muscular fibre, when prepared as already mentioned, so as, by long maceration and subsequent boiling with frequent change of water, to be * In respect to economical purposes, it may be proper here to observe, that all animal substances whatever, exclusive of carbonate and phosphate of lime, may be converted into 2 substances of much utility, namely, glue, under which term I include all the varieties mentioned in this paper, and soap, with the additional advantage, that those parts which would be rejected in making the one, are the most proper to prepare the other. The offensive smell of Chaptal's soap is considered as an objection j but this may be removed, by exposing the soap for some time, in flat vessels, to the air ; after which, it may be reduced to the proper degree of consistency, by a second boiling. — Ong. VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 730 very nearly deprived of the whole of its gelatinous part, is not easily brought into the putrid state. A small quantity was kept moistened with water, during the whole of last April ; in the course of which time it acquired a musty but not a putrid smell ; neither were the fibres reduced to a pulpy mass*. I am inclined therefore to suspect, that strong and completely formed muscular fibre, considered as a distinct substance, is not of easy putrescibility ; and that the readiness with which muscle in general enters into putrefaction, is principally owing to the gelatin, which is combined and mixed with it, in a large proportion, as a component part, and which, with the natural quantity of moisture, is requisite to give the fibre a proper degree of toughness and flexibility. The residuum afforded by muscular fibre which had been long steeped in dilute nitric acid, and afterwards immersed in ammonia, consisted chiefly of fat, mixed with a small portion of the fibre which had not been sufficiently acted on by the acid; and little or no earthy matter was thus obtained. But when the prepared muscular fibre was dissolved in boiling nitric acid, a complete solution, resembling that of albumen, in its general properties, was formed ; and some fat floated in drops at the top of the liquor. Ammonia was then added, so as to super-saturate the acid, and produced the same effects as on the nitric solutions of albumen, excepting that a copious white precipitate was obtained. This precipitate, while moist, was agitated with a quantity of acetous acid, which dissolved, and separated, a small portion of phosphate of lime; but the remainder, and by much the greatest part of this precipitate, was scarcely attacked, even when the acid was boiled. When exposed to a red heat it became dark gray, and then nearly white ; after which it was in the state of carbonate of lime. Another part was dissolved in nitric acid, and lime was precipitated by carbonate of soda. The slight excess of the latter was then saturated by acetous acid ; and the whole was boiled, to expel the carbonic acid ; after which the liquor, from its effects on solutions of lime, barytes, &c. evidently contained oxalic acid in solu- tion : the precipitate was therefore oxalate of lime, mixed with a very small quan- tity of phosphate of lime. 200 gr. of the dry muscular fibre, dissolved and boiled with nitric acid, afforded 17 gr. of this precipitate. Though it is known that the gelatinous liquor obtained from muscle by boiling water, contains phosphate of soda, and of lime, yet I did not imagine that the greater part of the latter could be so completely separated. I therefore in some measure repeated the experiment on the muscle of veal ; and found phosphate of soda, and of lime, in the liquor. But when the muscle was afterwards dissolved in boiling nitric acid, and the solution was saturated with ammonia, I was surprized to find that, though the same change in colour was produced as in all the former experiments, the liquor remained transparent ; and even after several days only a few scattered particles appeared at the bottom of the vessel. Another experiment was made on the recent * A portion of this muscular fibre was kept under water 2 months ; it did not however become putrid, nor was it converted into that fatty substance which is obtained from recent muscle under similar circumstances. — Orig. 5B 2 740 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. muscle of mutton; but this was immediately dissolved in nitric acid, without being previously boiled in water. The fat being separated, the solution was, as before, saturated with ammonia ; and, as usual, became of a deep orange colour, or yellowish brown : in a few hours also, a small quantity of a white precipitate subsided. This precipitate however was completely and readily soluble in acetous acid : and in every respect proved to be phosphate of lime. Before proceeding it will be proper to observe, that the liquor from which the above precipitate was separated, as well as those afforded by the muscle of veal, by the prepared muscle of beef, by the solutions of tortoise-shell and of albumen, in boiling nitric acid, subsequently saturated by ammonia, all contained a con- siderable portion of uncombined oxalic acid, which was separated by acetite of lime, and of lead. But I did not find oxalic acid in the solutions formed by immersing these bodies, for a long time, in cold and dilute nitric acid ; neither did I find oxalic acid in solutions made by dissolving these substances in boiling muriatic acid. It is evident therefore, that the oxalic acid observed in the above experiments, was a product of the operations, and not an educt of the substances. We may conclude, from the experiments on the muscular substances which have been lately mentioned, that they contain lime, in various proportions, and in 2 different states, viz. carbonate and phosphate ; and that the greater part of the latter is gradually separated, in conjunction with the gelatin, by means of boiling water. I would not however have it understood that phosphate of lime is an essential ingredient in gelatinous substances : for, on the contrary, isinglass, which is a perfectly gelatinous body, affords but a mere visible trace of it. The muscular fibre of beef appears to have been nearly deprived of its phosphate of lime, by the long continued and repeated boiling in water to which it had been subjected ; but still so large a quantity of lime remained, that when oxalic acid was formed by the action of the boiling nitric acid, it combined with the lime, and formed an oxalate, which amounted to 17 gr., from 200 gr. of the dry mus- cular fibre, dissolved in nitric acid, and precipitated by ammonia. I do not know what quantity of lime was separated with the gelatin, as I was then only intent on preparing the fibrous part of the muscle; but, from the quantity of lime which remained, and which afterwards combined with the oxalic acid, it is evident, that in the muscle of beef there is a considerable portion of earthy matter ; and as, by the experiment on the muscle of veal, scarcely any precipitate was obtained after it had been boiled, and as but a small portion of phosphate of lime was present in the gelatinous liquid, it appears that in this muscle the whole of the small portion of lime which it contained was in the state of phosphate ; and this being nearly separated, there did not remain any part of uncombined lime, or carbonate of lime, which, by uniting with the oxalic acid, subsequently produced, would form an oxalate; and as lime, in the states of phosphate and carbonate, is so much more abundant in the muscle of beef than in that of veal, we may infer, that the earthy matter is more abundant in the VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 741 coarse and rigid fibre of adult and aged animals, than in the tender fibre of those which are young ; and this seems to be corroborated by the tendency to morbid ossification, so frequently observed in aged individuals of the human species. Gelatin, albumen, and muscular fibre, not only differ very much from each other by the relative quantity of their saline or earthy residua, but also by the proportion of one of their essential and elementary principles, namely carbon. 500 gr. of isinglass, made perfectly dry by distillation, yielded 56 gr. of coal, from which, 1.50 gr. of earthy residuum, obtained by incineration, being deducted, the proportion of coal appears to have been 54.50 gr. 500 gr. of dry albumen afforded 74.50 gr.; and as the saline residuum amounted to 11.25 gr., the quantity of mere coal was 63.25 gr. 500 gr. of tortoise-shell yielded 80 gr. of coal; from which 3 gr. of earthy matter being deducted, 77 gr. remain, for the proportion of coal. And 500 gr. of the dry prepared muscular fibre of beef, when distilled, left 108 gr. of coal, which, by incineration, afforded 25.60gr. of earthy residuum; the coal may therefore be estimated at 82.40 gr. There appears much reason therefore to believe, that the gelatinous substances and muscular fibre, differ from simple and unorganized albumen, by a diminution of the carbonic principle in the one, and by an excess of it in the other; and as, in vegetables, the fibrous part is that which contains the largest proportion of carbon, so, in respect to the other animal substances, muscular fibre appears to contain the greatest quantity of it. The nature of the residua obtained by the incineration of the substances lately mentioned, also deserves to be noticed. Only 1 .50 gr. was obtained from 500 gr. of isinglass ; and, as far as the quantity would allow, was proved to be phosphate of soda, mixed with a very minute proportion of phosphate of lime. The 3 gr. afforded by tortoise-shell, consisted of phosphate of soda and of lime, with some traces of iron : it is probable that the latter was accidentally present. The pre- pared muscular fibre of beef yielded 25.60 gr. ; the greatest part of which was carbonate of lime, mixed with some pure lime, and a small portion of phosphate ; there can be no doubt but that the latter would have been more abundant, had it not been for the repeated boilings to which the muscular fibre had been sub- jected. The recent muscles of veal and mutton were with great difficulty reduced to ashes ; for, towards the end of the process, the ashes and remaining coal be- came coated and glazed with saline matter, which appeared to be soda, partly in the state of phosphate; and it is not a little remarkable that the 11.25 gr., ob- tained from albumen, consisted chiefly of soda, in a caustic state, by reason of the long continued heat, mixed with a small quantity of phosphate of soda, and a very minute portion of phosphate of lime. Pure albumen therefore, which has not been subjected to the effects of organization, appears to contain a considerable portion of saline matter, and very little of any earthy substance ; but the contrary seems to happen in bodies which, though evidently derived from albumen, have suffered various changes by the action of the vital principle; which may be con- sidered as the cause of organization, by which these bodies are differently modified, 74'2 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. according to the nature of the parts of animals which, singly or conjointly, they are employed to form. In these bodies the quantity of the saline substances appears to be diminished, while that of the earthy matter is increased, especially in the coarser kinds of muscular fibre. On a comparison of the chemical properties of the substance which remains, after the separation of gelatin from the great variety of animal substances which have been so often mentioned in the course of this paper, and which need not therefore now be repeated, there can scarcely be any doubt but that it is one and the same substance, in different states of density and texture. For the similarity of its nature was proved by, 1st. The effects of fire, and the products obtained by distillation. 2dly. Its very difficult solubility by long digestion in boiling water. 3dly. The effects produced by re-agents, on the water in which bodies like inspis- sated albumen or tortoise-shell had been boiled. 4thly. The effects of acids, particularly nitric acid, of ammonia, and of caustic lixivium of potash. 5thly. The animal soap which was formed ; and the precipitate obtained from it, by the addition of acetous or muriatic acid*. Gthly. The difficulty attending the putre- faction of the substance in question, when pure and dense. The similarity in all these properties, appears to be a full proof, that it is the same substance which constitutes the principal part of membrane, sponge, horn, hair, &c. and even of muscular fibre. Besides, on comparing the properties of this substance with those of pure albumen in a state of inspissation, so evident a resemblance in every respect is dis- covered, that few I believe will hesitate to pronounce albumen to be the original substance from which tortoise-shell, hair, horn, muscular fibre, &c. have been de- rived and formed. There is much reason to believe that gelatin, though it appears so different in many respects from albumen, is yet formed from it-f~. * This appears to be a strong marked character of the albuminous substances. + In addition to the chemical properties by which gelatin and albumen are distinguished, particularly the different effects observed when these 2 substances were treated with nitric acid, I shall mention some others, not less remarkable, which are produced by the muriatic acid. When any of the varieties of gelatin, such as glue, isinglass, &c. are immersed in cold muriatic acid, they are dissolved in a few hours ; and the solutions thus formed surfer no apparent change, even in the course of several months. In like manner, gelatin may be separated and dissolved from bodies which contain it, such as sponge, bladder, skin, and muscle ; but the part which remains undissolved, and which, with the other substances formerly mentioned, I regard as formed of albumen more or less organized, is very differently affected; for when coagulated albumen, the undissolved part of bladder, muscular fibre, feather, quill, tortoise- shell, wool, and hair, were separately steeped in muriatic acid, they gradually became of a dark colour, and the acid was tinged with the same. The colour afforded by albumen was deep blue, inclining to purple ; that of bladder was brownish purple ; feather, quill, tortoise-shell, and muscular fibre, afforded a beautiful deep blue ; and wool, and hair, like bladder, produced a brownish purple. The change began to take place in the coagulated albumen in about 8 or 10 days; but wool and hair were the last affected. In about 3 months, the different liquids were become very dark, though scarcely any perceptible quantity of the immersed substances appeared to be dis- solved. Nitric acid, in a small proportion, changed these blue and brownish purple liquors to deep yellow ; and ammonia, being then added, changed them to orange colour, and produced all those effects which were observed, when the nitric solutions of these substances were thus treated. — Orig. VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 743 It may be recollected, that in a former part of this paper mention was made, that tortoise-shell, horn, muscular fibre, and inspissated albumen, after long immersion in very dilute nitric acid, and after being well washed, were soluble in boiling water; and that a substance was formed, which, by becoming liquified when heated, by being soluble in boiling water, by being precipitated by the tanning principle and by nitro-muriate of tin, and lastly, by forming a gelatinous mass when the aqueous solution was sufficiently evaporated and cooled, approached and resembled gelatin. It would be perhaps too hasty to assert, that gelatin was thus absolutely formed ; but if a substance so very similar to it could be thus produced, we may with some reason conclude that the real gelatin, with its various modifications, is formed from albumen, by the more efficacious and delicate operations of nature. In attempting to prove that albumen or the coagulating lymph is the original animal substance, I have hitherto only stated chemical facts ; but when the phe- nomena attending incubation are considered ; when the experiments made by emi nent physiologists, such as Haller, Maitre Jean, and Malpighi, are viewed ; when the oviparous foetus is seen to be progressively formed in and from the albumen of the egg, so that, on the bursting of the shell which separated it from external matter, the young animal comes forth complete in all its parts ; when such strong facts as these are corroborated by those afforded by chemistry, it can scarcely be doubted that albumen is the primary animal substance, from which the others are derived ; and there is much cause to believe that the formation of gelatin, and of the animal fibre especially, begins with the process of sanguification in the fcetus. As the 3 principal and essential component parts of the blood, viz. albumen, gelatin, and fibre*, appear therefore to compose the various parts of animals, in such a manner that one, being predominant, influences the nature of that part of the animal which it is principally employed to form ; and as albumen, gelatin, and fibre, by relative proportion, by the degrees of density, by the effects of organiza- tion which singly or conjointly they have experienced, by the texture of the animal substance which they, as materials and thus modified, have concurred to produce, and by the proportion of natural or inherent moisture peculiar to each part of dif- ferent animals, present an immense series of complicated causes ; so are the effects found to be no less numerous and diversified, by the infinite variety in texture, flexibility, elasticity, and the many other properties peculiar to the various parts which compose the bodies of animals. * The whole of the blood, which by anatomists is divided into serum, red globules, and coagulating lymph, when chemically examined, is found to consist of albumen, gelatin, and fibre. The serum which remains liquid after the coagulation of the blood, is composed of albumen, gelatin, some saline matter, and much water. The clot or crassamentum also affords, by repeated washing, a large pro- portion of albumen and gelatin j after which a substance remains, in appearance very analogous to muscular fibre, excepting that it is in a more attenuated state. This substance, called fibrin by chemists, may be regarded as that part of the blood which has undergone the most complete animalization ; and from which the muscular fibre and other organs of the body are formed. — Orig. 744 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. XVII. On the Electricity excited by the mere Contact of Conducting Substances of different kinds. By Mr. Alex. Folta, F. R. S. Prof, of Nat. Philos. in the University of Pavia. From the French, p. 403. The chief of these results, and which comprehends nearly all the others is the construction of an apparatus which resembles in its effects, viz. (such as giving shocks to the arms, &c.) the Ley den phial, and still better electric batteries weakly charged ; acting continually, or whose charge, after each explosion, recharges itself again ; which in short becomes perpetual, from one infallible charge, from one action or impulse on the electric fluid ; but which besides differs essentially from the other, by thi6 continual action which is proper to it, and because that instead of consisting, like the ordinary phials and electric batteries, in one or more isolated plates, or thin layers of those bodies deemed the only electrics, and armed with conductors or bodies called non-electrics, this new apparatus is formed only of a number of these last bodies, chosen even among the best conductors, and so the far- thest removed, according to the usual opinion, from the electric principle. This asto- nishing apparatus is nothing but an assemblage of a number of good conductors of a different kind, arranged in a certain manner. Thus, 30, 40, 60, or more pieces of copper, or better of silver, each applied to a piece of tin, or still much better of zinc ; and an equal number of layers of water, or of some other liquid which may be a better conductor than simple water, as salt water, lye, &c. or of bits of card or leather, &c. soaked in such liquids. Of such layers, interposed between each couple or combination of 2 different metals, one such alternate series, and always in the same order, of these 3 kinds of conductors, is all that constitutes M. Volta's new instrument ; which imitates so well the effects of the Leyden phial or electric bat- teries ; not indeed with the force and explosions of these, when highly charged ; but only equalling the effects of a battery charged to a very weak degree, of a battery however having an immense capacity, but which besides infinitely surpasses the virtue and the power of these same batteries ; as it has no need, like them, of being charged before hand, by means of a foreign electricity ; and as it is capable of giving the usual commotion as often as ever it is properly touched. This appa- ratus, as it resembles more the natural electric organ of the torpedo, or of the elec- tric eel, than the Leyden phial and the ordinary electric batteries, M. Volta calls the artificial electric organ. For the construction of this instrument, M. V. pro- vides some dozens of small round metal plates, of copper, or tin, or best of silver, about an inch in diameter, like shillings or half-crowns, and an equal number of plates of tin, or much better of zinc, of the same shape and size : these pieces he places exactly one upon another, forming a column, pillar, or pile. He provides also as many small round pieces of card, or leather, or such like spongy matter, capable of imbibing and retaining much of the water, or other liquid, when soaked in it. These soaked roullets or circles are to be a little less in diameter than the small metal discs or plates, that they may not jut out beyond them. All these VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 745 discs are then placed horizontally on a table, one over another continually alter- nating, in a pile as high as it will well support itself without tottering and falling down ; beginning with a plate of either of the metals, as for instance the silver, then upon that one of zinc, over which is to be put the soaked card ; then other 3 disks, over these in the same order, viz. a silver, next a zinc, and then another moistened card, &c. After having raised the pile to about 20 of these stages or triads of plates, it will be already capable, not only of affecting Cavallo's electrometer, assisted by the con- denser, so as to raise it 10 or 15°, charging it by a simple touching, so as to cause it to give a spark, &c. as also to strike the fingers with which we touch the top or bottom of the column, with several small snaps, the fingers being wetted with water. But if to the 20 sets of triplets of the plates be added 20 or 30 more, disposed in the same order, the actions of the extended pile will be much stronger, and be felt through the arms up to the shoulders; and by continuing the touchings, the pains in the hands become insupportable. Mr. V. constructs and combines his apparatus in various ways and forms, more or less powerful, convenient, or amusing. One is as follows, fig. 1, pi. 13, which he calls a couronne de tasses. He disposes in a row a number of cups, of wood, or earth, or glass, or any thing but metal, half filled with pure water, or salt water, or lye ; these are all made to communicate in a kind of chain, by several metallic arcs, of which one arm or link Aa, or only the extremity a, immersed in one of the cups, is of copper, or of copper silvered, and the other z, immersed in the fol- lowing cup, is of tin, or rather of zinc, the 2 being soldered together near the crown of the arch. It is evident that a series of these cups, thus connected to- gether, either in a straight or curved line, by the 2 metals and the intermediate liquid, is similar to the pillar or pile before described, and consequently will exhibit similar effects. Thus, to produce the commotion or sensation in the hands and arms, we need only dip one hand into one of the cups, and a finger of the other hand into another cup, sufficiently distant from the former ; then the action will be so much the stronger as the 2 cups are farther asunder, or have the more in- termediate cups ; and consequently the greatest by touching the first and the last in the chain. As to the structure in the other method, by the column or pile, Mr. V. found out various ways to prolong and extend it, in multiplying the metal plates without shaking it down ; to render this instrument convenient, portable, and durable ; and, among others, the 3 methods exhibited on figs. 2, 3, 4, pi. 13. In fig. 2, m m m m, are upright bars or rods, to the number of 3, or 4, or more, erected from the bot- tom of the pile, and extended to a convenient height, inclosing the pile like a cage to prevent its falling. These rods may be either of glass, wood, or metal ; only, in this last case, they must be hindered from touching the metal plates ; which may be done, either by covering each metal rod with a glass tube, or by interpo- sing between them and the pile some bands of cerecloth, or oiled paper, or sim- VOL. XVIII. 5 C 7^6 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. pie paper, or any imperfect conducting substance. But the best expedient for forming the instrument of a great number of plates, as of 60, 80, 100, is to divide the pile into 2 or more, as in the figures 3 and 4 ; where the pieces have all their respective positions or communications, as if it was one pile only, plied and turned. In all these figures, the different metal plates are denoted by the letters a and z, the initials of argent and zinc, and of the wet discs of card, or leather, &c. interposed at each pair of those metals, by a layer or band shaded black. The dotted lines show the contact of each couple of the metal plates a and z, where they may be conveniently soldered together, cc, cc, cc, are metal plates forming the communi- cation between one column, or section of a column, and another ; and b, b, b, b, b, are basins of water, in communication with the bottoms or extremities of the piles. Mr. Volta concludes with various remarks and cautions in using this instrument; showing that it is perpetual in its virtue, renewing its charge spontaneously, and serving most of the purposes of the ordinary electrical machines, and even affecting and manifesting its power by most of the human senses, viz. feeling, tasting, hear- ing, and seeing. (See a Note at the end of this Fblume.J XVllh Some Observations on the Head of the Ornithorhynchus Paradoxus. By Everard Home, Esq. F. R. S. p. 432. The specimens of this extraordinary animal which have been sent to Europe, have been deprived of the internal parts, and the skins are mostly dried, and but badly preserved. Such imperfect specimens have raised the curiosity of the natu- ralist, and excited the ardor of the anatomist, without satisfying their inquiries. It was natural, under these circumstances, to reserve any observations which had been made on this newly discovered quadruped, till the entire animal should be brought home preserved in spirit, and enable us to examine the structure of its different organs ; but finding that Professor Blumenbach has been led to believe that it was an animal without teeth, an opinion which must have arisen from the imperfect state of the specimen he examined, it appeared highly proper to do away the mis- take, and lay before the r. s. such observations respecting the head of this extraor- dinary animal, as I have been enabled to make. My opportunities of examining the Ornithorhynchus were procured through Sir Jos. Banks ; who permitted me to have drawings made from the skin of one of a very large size, and which, from hav- ing been preserved in spirit, was more perfect than any of the dried specimens. Any general description of the beak of this animal, which is its most conspicuous peculiarity, becomes unnecessary, as the accompanying drawings will give a suf- ficiently correct idea of the outward appearances, to answer the present purpose. It was not permitted to examine the head anatomically ; but a smaller dried spe- cimen, received from Sir Jos. Banks, furnished me with the following observations. The beak of the Ornithorhynchus, when cursorily examined, appears so strongly to resemble that of the duck, as to lead to the belief of its being calculated for VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 747 exactly the same purposes ; it will however be found to differ materially from it, in a variety of circumstances. The beak is found, on examination, not to be the animal's mouth, but a part added to the mouth, and projecting beyond it. The cavity of the mouth is situated as in other quadrupeds, and has 2 grinding teeth on each side, both in the upper and lower jaw; but, instead of incisor teeth, the nasal and palate bones are continued forwards, lengthening the anterior nostrils, and forming the upper part of the beak ; and the 2 portions of the lower jaw, in- stead of terminating at the symphysis, where they join, become 2 thin plates, and are continued forwards, forming the under portion of the beak. This structure differs materially from the bill of the duck, and indeed from the bills of all birds, since in them, the cavities of the nostrils do not extend beyond the root of the bill; and, in their lower portions, which correspond to the under jaw of quadrupeds, the edges are hard, to answer the purpose of teeth, and the middle space is hollow, to receive the tongue. But in this animal the 2 thin plates of bone are in the centre ; and the parts which surround them are composed of skin and membrane, in which a muscular structure probably is enclosed. The teeth have no fangs which sink into the jaw, as in most quadrupeds, but are imbedded in the gum ; and have only lateral alveolar processes, from the outer and inner edges of the jaw, to secure them in their places, but no transverse ones between the 2 teeth. The tongue is extremely short, not half an inch long ; and the moveable portion not more than a quarter of an inch ; the papillae on its sur- face are long, and of a conical form. When the tongue is drawn in, it can be brought entirely into the mouth ; and when extended can be projected about a quarter of an inch into the beak. The organ of smell in this animal, differs in some particulars from that of the quadrupeds in general, as well as of birds. The external openings of this organ are placed nearly at the end of the beak, there being only the lip beyond them , while the turbinated bones are in the same rela- tive situation to the other parts of the skull as in quadrupeds ; by which means, there are 2 cavities the whole length of the beak, superadded to the organ of smell. The turbinated bones in each nostril are 2 in number, and are distinct from each other. That next the beak is the longest, has a more variegated surface than in the duck, and has the long axis in the direction of the nostril ; the posterior one is short, projects farther into the nostril, and the ridges are in a transverse direc- tion. The posterior nostrils do not open directly under the turbinated bones, as in the duck, but about an inch farther back, and are extremely small ; the cavities of the nose, in this animal, are therefore uncommonly extensive ; they reach from the end of the beak nearly to the occiput. The beak itself is formed by the projecting bones already mentioned, covered with a smooth black skin, which extends some way beyond the bones, both in front and laterally, forming a moveable lip. This lip is so strong, that when dried or hardened in spirit, it seems to be rigid ; but when moistened is very pliant, and has probably a muscular structure. The under portion of the beak has a lip equally 5 C 2 748 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. broad with the upper : this has a serrated edge ; but the serrae are confined to the soft part, not extending to the membrane covering the bone, and are not met with in the upper one. The extent of the lips beyond the bones, is distinctly marked in the drawings. There is a very curious transverse fold of the external black smooth skin, by which the beak is covered, projecting all round, exactly at that part where the beak has its origin. Its apparent use seems to be to prevent the beak being pushed farther into the soft mud, in which its prey may lie concealed, than up to this part, which is so broad that it must completely stop its progress. The nerves that supply the beak, in their general course, size, and number, seem very closely to correspond with those of the bill of the duck. The cavity of the skull bears a greater general resemblance to that of the duck than of quadrupeds : there is a very uncommon peculiarity in it, which is, that there is a bony falx of some breadth, but no bony tentorium. This is met with in no quadruped that I know of: it is found in a small degree in some birds, as the spoon-bill, and the parrot ; but not at all so as to resemble the falx in this animal. The orifice of the eye lids is uncommonly small, for the size of the animal ; but the eye itself was not in a state to be examined. The external opening of the ear was so small as not readily to be perceived : it is simply an orifice ; but the meatus enlarges considerably beyond the size of the opening, and passes some way under the skin, before it reaches the organ, which in this specimen had been destroyed. In the duck, the orifice leading to the ear is very large, when compared with the opening in this animal. When we consider the peculiarities in the structure of the nose of this animal, which lives in water, it is natural to conclude the organ is fitted to smell in water, and the external nostrils are so placed, to enable it to dis- cover its prey by the smell ; for that purpose, the animal can apply its nose, with great ease, to the small recesses in which its prey may be concealed. The struc- ture of the beak is not such as enables it to take a firm hold ; but, when the mar- ginal lips are brought together, the animal will have a considerable power of suc- tion, and in that way may draw its prey into its mouth. Explanation of the Figures. — PI. 13, fig. 5, is a view of the beak, to show the situation of the open- ings of the external nostrils, marked aa. Fig. 6, another view of the beak, exposing the under portion. Fig. 7, a lateral view, to show the opening of the lips, and the situation of the eye and ear. a. The eye. b. The ear. Fig. 8, a view of the upper jaw and palate, to show the teeth in their situation. Fig. 9, a similar view of the under jaw. Fig. 10, the bones which form the beak delineated, and the soft sur- rounding parts only marked in outline. Fig. 1 1, a similar view of the bones forming the lower portion of the beak. XIX. Experiments on the Solar, and on tlie Terrestrial Rays that occasion Heat ; wtth a Comparative View of the Laws to which Light and Heat, or rather the Rays which occasion them, are subject, in order to determine w/iether they are the same, or different. By William Herschel, LL. D., F. R. S. Part 1. p. 437. In the first part of this paper it has been shown, that heat derived immediately from the sun, or from candent terrestrial substances, is occasioned by rays etna- YOL. XC.] PHILOSOPHICAL TRANSACTIONS. 749 nating from them ; and that such heat-making rays are subject to the laws of re- flection and refraction. The similarity between light and heat in these points is so great, that it did not appear necessary to notice some small difference between them, relating to the refraction of rays to a certain focus, which will be mentioned hereafter. But the next 3 articles of this paper will require, that while we show the similarity between light and heat, we should at the same time point out some striking and substantial differences, which will occur in our experiments on the rays which occasion them, and on which hereafter we may proceed to argue, when the question reserved for the conclusion of this paper, whether light and heat be occasioned by the same or by different rays, comes to be discussed. Art. 4. Different Ref Tangibility of the Rays of Heat. — We might have con- cluded this article in the first part of this paper, as a corollary of the former 3 ; since rays that have been separated by the prism, and have still remained subject to the laws of reflection and refraction, as has been shown, could not be otherwise than of different refrangibility ; but we have something to say on this subject, which will be found much more circumstantial and conclusive than what might have been drawn as a consequence from our former experiments. However, to begin with what has already been shown, we find that 2° of heat were obtained from that part of the spectrum which contains the violet rays, while the full red colour, on the opposite side, gave no less than 7° ; and these facts ascertain the different refrangibility of the rays which occasion heat, as clearly as that of light is ascertained by the dispersion and variety of the colours. For, whether the rays which occasion heat be the same with those which occasion the colours, which is a case that our foregoing experiments have not ascertained, the arguments for their different refrangibility rests on the same foundation, namely, their being dispersed by the prism ; and that of the rays of light being admitted, the different refran- gibility of the rays of heat follows of course. So far then a great resemblance a ain takes place. I must now point out a very material difference, which is, that the rays of heat are of a much more extensive refrangibility than those of light. In order to make this appear, I shall delineate a spectrum of light, by assuming a line of a certain length ; and dividing it into 7 parts, according to the dimensions assigned to the 7 colours by Sir Isaac Newton, in the 4th figure of the second part of his Optics, I shall represent the illuminating power of which each colour is possessed, by an ordinate drawn to that line. And here, as the absolute length of the ordinates is arbitrary, provided they be proportional to each other, I shall assume the length of that which is to express the maximum, equal to f£ of the whole line. Thus, let Ga, fig. 12, pi. 13, represent the line that contains the arrangement of the co- lours, from the red to the violet. Then, erecting on the confines of the yellow and green the line lr=-§4 of gq, it will represent the power of illumination of the rays in that place. For, by experiment already delivered, we have shown that the maximum of illumination is in the brightest yellow or palest green rays. From 750 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. the same experiments we collect, that the illuminations of yellow and green are equal to each other, and not much inferior to the maximum ; this giveN us the ordinates k and m. Then, by the rest of the same experiments, we Obtain also the ordinates h, i, n, o, p, with sufficient accuracy for the purpose here intended. All these being applied to the middle of the spaces which belong to their respective colours, we have the figure gr»g, representing what may be called the spectrum of illumination. We are now, in the same manner, to find a figure to express the heating power of the refracted prismatic rays, or what may be called the spectrum of heat. In order to determine the length of our base, I examined the extent of the invisible rays, and found, that at a distance of 2 inches beyond the visible red, my ther- mometer in a few minutes acquired 1°^- of heat. The extent of the coloured spectrum at that time, or the line which answers to Ga in the figure, measured 2.997 inches. If 2 inches had been the whole of the extent of the invisible part, it might be stated to be in proportion to the visible one as 2 to 3 ; but we are to make some allowance for a small space required beyond the last ordinate, that the curve of the heating power drawn through it may reach the base ; and indeed, at 24- inches beyond visible red, I could still find 4- degree of heat. It appears there- fore sufficiently safe, to admit the base of the spectrum of heat aq, to be that of the spectrum of light gg, as 5^ to 3 ; or conforming to the Newtonian figure before mentioned, the base of which is 3.3 inches, as 574 to 33« Now if we assume for the maximum of heat, an ordinate of an equal length with that which was fixed on for the maximum of light, it will give us a method of comparing the 2 spectra together. Accordingly I have drawn the several ordinates b, c, d, e, p, g, h, i, k, l, m, n, o, p, of such lengths as, from experiments made on purpose, it appeared they should be, in order to express the heat indicated by the thermometer, when placed on the base, at the several stations pointed out by the letters. A mere in- spection of the 2 figures, which have been drawn as lying on each other, will enable us now to see how very differently the prism disperses the heat-making rays, and those which occasion illumination, over the areas asqa, and grog, of our 2 spectra ! These rays neither agree in their mean refrangibility, nor in the situa- tion of their maxima. At r, where we have most light, there is but little heat; and at s, where we have most heat, we find no light at all ! Exper. 21. The Sines of Refraction of the Heat-making Rays, are in a Constant Ratio to the Sines of Incidence. I used a At j inch At , inch Standard# prism with a refracting angle of 6* 1°; and placing the Min. N°4. N° 1. N° 2. thermometer N° 4 half an inch, and N° 1 one inch, 67 66 6J beyond the last visible red colour, I kept N° 2 by 5 6*9 67 63J the side of the spectrum, as a standard for tempera- 8 9* '* * ture. Here in 8 minutes, the thermometer at half an inch from visible colour, rose 5-J- degrees; and, at 1 inch from the same, the other thermometer rose 3±; while the temperature, as appears by N° 2, remained without change. 55 55 57 54| 58 55 58f 55 VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 751 I now took a prism with an angle of 45°, and, placing the thermometers as before, I had as follows: Here we also had, in 5g 10 minutes, a rise of 7° in the thermometer N° 4, and of 3-f- in J>1 N° 1 ; while N° 2 remained stationary. I tried now all the 3 angles of a prism of whitish glass: they were of 63, 62, and 55 degrees ; and I found invisible rays of heat to accompany all the visible spectra given by these angles. I tried a prism of crown glass, having an angle of 30° ; and found invisible heat rays as before. I tried a prism of flint glass, with so small an angle as J 9°, and again found invisible heat rays. I made a hollow prism, by cementing together 3 slips of glass of an equal length, but unequal breadth, so as to give me different refracting angles : they were of 51°, 62° 30', and 66° 30'. Then filling it with water, and receiving the spectrum, when exposed to the sun as usual, on the table. I placed the thermo- meter N° 1 at .45 inch behind the visible red colour, and N° 5 in the situation of the standard. The refracting angle of the prism was 62° 30' ; and in 5 minutes the thermometer received 1-f- degrees of heat from the invisible rays. On trying the other angles, I likewise found invisible heat rays, in their usual situation be- yond the red colour. Now, setting aside a minute inquiry into the degrees of heat occasioned by these invisible rays, I shall here only consider them as an ad- ditional part, annexed to the different quantities of heat which are found to go along with the visible spectrum ; in the same manner as if, in the spectrum of light, another colour had been added beyond the red. Then, as from the fore- going experiments it appears, that a change of the refracting medium, and of the angle by which the refractions were made, occasioned no alteration in the relative situation of the additional part ag, with respect to gq ; and as the part Get is already known to follow the law of refraction we have mentioned, it is equally evident that the additional heat of ag must follow the same law. We do not enter into the dispersive power of different mediums with respect to heat, since that would lead us farther than the present state of our investigation could authorize us to go ; the following experiment however will show that, as with light so with heat, such dispersive power must be admitted. Exper. 11. Correction of the Different Refrangibility of Heat, by contrary Refraction in Different Mediums. — I took 3 prisms ; one of crown glass, having an angle of 25° ; another of flint glass, with an angle of 24 ; and a third of crown glass, with an angle of 10°. These being put together, as they are placed when experiments of achromatic refractions are to be made, I found that they gave a spectrum nearly without colour. The composition seemed to be rather a little over adjusted; there being a very faint tinge of red on the most refracted side, and of violet on the least refracted margin. I examined both extremes by 2 ther- mometers ; keeping N° 3 as a standard, while N° 2 was applied for the discovery of invisible rays ; but I found no heat on either side. After this, I placed N° 2 in the middle of the colourless illumination ; and in a little time it rose 2°, while 752 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. N° 3 still remained unaltered at some small distance from the spectrum. This quantity was full as much as I could expect, considering the heat that must have been intercepted by 3 prisms. Thus then it appears, that the different refrangi- bility of heat, as well as that of light, admits of prismatic correction. And we may add, that this experiment also tends to the establishment of the contents of the preceding one ; for the refrangibility of heat rays could not be thus corrected, were the sines of refraction not in a constant ratio to those of incidence. Exper. 23. In Burning-glasses, the Focus of the Rays of Heat is Different from the Focus of the Rays of Light. — I placed the burning lens, with its aperture reduced to 3 inches, in order to lessen the aberration arising from the spherical figure, in the united rays of the sun ; and being now apprised of the different refrangibility of the rays of heat, and knowing also that the least refrangible of them are the most efficacious, I examined the focus of light, by throwing hair- powder, with a puff, into the air. This pointed out the mean focus of the illu- minating rays, situated in that part of the pencil which opticians have shown to be the smallest space into which they can be collected. That this may be called the focus of light, our experiments, which have proved the maximum of illumination to be situated between the yellow and green, and therefore among the mean refran- gible rays of light, have fully established. The mean focus being thus pointed out by the reflection of light on the floating particles of powder, I held a stick of sealing-wax ls.6 or 4 beats of my chronometer, in the contracted pencil, half an inch nearer to the lens than the focus. In this time, no impression was made on the wax. I applied it now half an inch farther from the lens than that focus ; and, in tV of a second, or 2 beats of the same chronometer, it was considerably scorched. Exposing the sealing-wax also to the focus of light, the effect was equally strong in the same time ; from which we may safely conclude, notwith- standing the little accuracy that can be expected, for want of a more proper appa- ratus, from so coarse an experiment, that the focus of heat, in this case, was certainly farther removed from the lens than the focus of light, and probably not less than ■{- of an inch ; the heat, at half an inch beyond the focus of light being still equal to that in the focus. Art. 5. Transmission of Heat-making Rays. — We enter now on the sub- ject of the transmission of heat through diaphanous bodies. Our experiments have hitherto been conducted by the prism, the lens, and the mirror ; these may indeed be considered as our principal tools, and, as such, will stand foremost in all our operations ; but the scantiness of this stock cannot allow us to bring our work to perfection. Nor is it merely the want of tools, but rather the natural imper- fection of those we have, that hinders onr rapid progress. The prism which we use for separating the combined rays of the sun, refracts, reflects, transmits, and scat- ters them at the same time ; and the laws by which it acts, in every one of these operations, ought to be investigated. Even the cause of the most obvious of its effects, the separation of the colours of light, is not well understood ; for, VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 753 in 2 prisms of different glass, when the angles are such as to give the same mean refraction, the dispersive power is known to differ. Their transmissions have been still less ascertained ; and I need not add, that the internal and external reflec- tions, and the scattering of rays on every one of the surfaces, are all of such a nature as must throw some obscurity on every result of experiments made with prisms. A lens partakes of all the inconveniencies of the prism ; to which its own defects of spherical aberrations must be added. And a mirror, besides its natural incapacity of separating the rays of light from the different sorts of heat, scatters them very profusely. But if we have been scantily provided with mate- rials to act on rays, it has partly been our own fault : every diaphanous body may become a new tool, in the hands of a diligent inquirer. My apparatus for transmitting the rays of the sun is of the following construc- tion: see fig. 13, pi. 13. In a box, 12 inches long, and 8 inches broad, are fixed 2 thermometers. The sides of the box are 2^- inches deep. That part of the box where the balls of the thermometers are, is covered by a board, in which are 2 holes of * inch diameter, one over each of the balls of the thermometers ; and the bottom of the box, under the cover, is cut away, so as to leave these balls freely exposed. There is a partition between the 2 thermometers, in that part of the box which is covered, to prevent the communication of secondary scat- terings of heat. Just under the opening of the transmitting holes, on the outside of the cover, is fixed a slip of wood, on which may rest any glass or other object, of which the transmitting capacity is to be ascertained. A thin wooden cover is provided, fig. 14, that it may be laid over the transmitting holes, occasionally, to exclude the rays of the sun ; and on the middle of the slip of wood, under the holes, a pin is to be stuck perpendicularly, that its shadow may point out the situation of the box with respect to the sun. The box, thus prepared, is to be fastened on 2 short boards, joined together by a pair of hinges. A long slip of mahogany is screwed to the lowest of these boards, and lies in the hollow part of a long spring, fastened against the side of the upper one. The pressure of the spring must be sufficiently strong to keep the boards at any angle ; and the slip of mahogany long enough to permit an elevation of about 85°. In order to see whether all be properly adjusted, expose the apparatus to the sun, and lift up the board which carries the box, till the directing pin throws the shadow of its head on the place where the point is fastened. Then hold a sheet of paper under the box, and, if the thermometers have been properly placed, the shadow of their balls will be in the centre of the rays passing through the transmitting holes to the paper. A screen of a considerable size, fig. 15, with a parallelogram- mic opening, should be placed at a good distance, to keep the sun's rays from every part of the apparatus, except that which is under the cover; and no more sun should be admitted into the room, than what will be completely received on the screen, interposed between the window and the apparatus. vol. xviii 5 D 754 PHILOSOPHICAL TRANSACTIONS. [ANNO 1 80O. As one of iae thermometers is to indicate a certain quantity of heat coming to it by the direct ray, while the other is to show how much of it is stopped by the glass laid over the transmitting hole, it becomes of the utmost consequence to have 2 thermometers of equal sensibility*. The difficulty of getting such is much greater than can be imagined: a perfect equality in the size and thickness of the balls is however the most essential circumstance. When 2 are procured, they should be tried in quick and in slow exposures. These terms may be explained by referring to fire heat ; for here the thermometers may be exposed so as to acquire, for instance, 30° of heat in a very short time; which may then be called a quick exposure: or they may be placed so as to make it require a good while to raise them to so many degrees; on which account the exposure may be called slow. It is true, that we have it not in our power to render the sun's rays more or less efficacious, and therefore cannot have a quick or slow exposure at our command; but a great difference would be found in the heat of a rising, or of a meridian sun : not to mention a variety of other causes, that influence the transmission of heat through the atmosphere. Now when thermometers are tried in various expo- sures, they should traverse their scales together with constant equality ; otherwise no dependence can be placed on the results drawn from experiments made with them, in cases where only a few minutes can be allowed for the action of the cause whose influence we are to investigate. The balls must not be blacked : for, as we have already to encounter the transmitting capacity of the glass of which these balls are made, it will not be safe to add to this the transmitting disposition of one or more coats of blacking, which can never be brought to an equality, and are always liable to change, especially in very quick exposures. Transmission of Solar Heat through Colourless Substances. Ecrper. 24. — I laid a piece of clear transparent glass, with a bluish-white cast, on one of the holes of the transmitting machine : the faces of this glass are parallel, and highly polished. Then, putting the cover over both holes, I placed the machine in the situation where the experiment was to be made, and let it remain there a sufficient time, that the thermometer might assume a settled temperature. For * The theory of the sensibility of thermometers, as far as it depends on the size of the balls, may be considered thus. Let d, d, s, *, t, t, be the diameters, the points on which the sun acts, and the points on which the temperature acts, of a large and a small thermometer having spherical balls i and let x toy be the intensity of the action of the sun, to the intensity of the action of the temperature, on equal points of the surface of both thermometers. Then we have * : s :: dl : d*, and t : t :: 4d* : 4d\ The action of the sun therefore will be expressed by dlx, d2x; and that of the temperature by Ad1}/, 4D*y; and the united action of both by (x — 4y) x cP, (x — 4y) x d*j which are to each other, as «P : d9. Now the total effect being as the squares of the diameters, while x : y remain in their incipient ratio, and the contents of the thermometers being as the cubes, the sensible effect pro- d* d1 11 duced on the particles of mercury, must be as — : — :: -r : -; that is, inversely as the diameters. The r a* d* a d small thermometer therefore will set off with a sensibility greater than that of the large one, in the same ratio. — Orig. N°5. N°l. Min. Sun. Bluish- white glass. o 67 67 1 68j 68i 2 70^ 69i 3 7H 70 4 72f 701 5 73 71| minutes. The result was VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 755 this purpose, an assistant thermometer, which should always remain in the nearest convenient place to the apparatus, will be of use, to point out the time when the experiment may be begun ; for this ought not to be done till the thermometers to be used agree with the standard. In order not to lose time after an experiment, the apparatus may be taken into a cool room, or current of air, till the thermometers it contains are rather lower than the standard ; after which, being brought to the required situation, they will soon be fit for action. All these precautions having been taken, I began the experiment by first writing down the degrees of the thermometers ; then, opening the cover at the time that a clock or watch showing seconds came to a full minute, I continued to write down the state of the thermometers for not less than 5 minutes, as annexed. Here the sun communicated, in 5 minutes, 6° of heat to the thermo- meter N° 5, which was openly exposed to its action ; while, in the same time, N° 1 received only 4± degrees by rays transmitted through the bluish-white glass : then, as 6 : 4-1 :: 1 : .750. This shows plainly, that only $ of the incident heat were transmitted, and therefore that 4- of it was intercepted by the glass. I shall here, as well as in the following experiments, point out the difference between heat and light, in order, as has been mentioned before, to lead to an elu- cidation of our last discussion. To effect this therefore, I have ascertained, with all the accuracy the subject will admit of, the quantity of light transmitted through such glasses as I have used; but as it would here interrupt the order of our subject, I have joined, at the end of this paper, a table, with a short account of the method that has been used in making it, wherein the quantity of light transmitted is set down ; and to this table I shall now refer. To render this comparative view more clear, we may suppose always 1000 rays of heat to come from the object : then 750 being transmitted, it follows that the bluish-white glass used in our experiment stops 250 of them ; and, by the table at the end of this paper, it stops 86 rays of light ; the number of them coming from the object also being put equal to 1000. It should be remarked, that when I compare the interception of solar heat with that of the light of a candle, it must not be understood that I take terrestrial to be the same as solar light ; but not having at present an opportunity of providing a similar table for the latter, I am obliged to use the former, on a supposition that the quan- tity stopped by glasses may not be very different. N° 5. N° l. Eocper. 25. I took a piece of flint glass, about 2-1- tenths of an sun. Flint glass. inch thick, and fastened it over one of the holes of the trans- J?f 69£ . 71$ 71 mitting apparatus. Here the heat-making rays gave, in 5 minutes, 724 72^ 54- degrees to the thermometer N° 5; and, by transmission through £H 73% the flint glass, 5° to N° 1 . Then, proceeding as before, we have 75| 74| 5d 2 756 PHILOSOPHICAL TRANSACTIONS. [anno 1800. 5j=.909; which shows that 9 1 rays of heat were stopped. In the table before referred to, we find that this glass stops 34 rays of light. Before proceeding it will be necessary to adopt a method of reducing the detail of the experiments into a narrower compass. It will be sufficient to say, that they have all been made on the same plan as the 2 which have been given. The obser- vations were always continued for at least 5 minutes ; and by examining the ratios of the numbers given by the thermometers in all that time, it may be seen that, setting aside little irregularities, there is a greater stoppage at first than towards the end ; but as it would not be safe to take a shorter exposure than 5 minutes, on ac- count of the small quantity of heat transmitted by some glasses, I have fixed on that interval as sufficiently accurate for giving a true comparative view. The ex- periments therefore may now stand abridged as follows. Exper. Q6. I took a piece of highly polished crown glass, of a greenish colour, and, cutting it into several parts, ex- Min. Sun. amined the .transmitting power of one of them, reserving 0 66% the other pieces for some experiments that will be men- 5 73 tioned hereafter. This glass therefore stops 259 rays of heat, and 203 of light. Exper. 27. I cut likewise a piece of coach glass into Min. Sun. several parts, and tried one of them, reserving also the 0 68f other pieces for future experiments. 5 75% It stops 214 rays of heat, and l6"8 of light. Exper. 28. I examined a piece of Iceland crystal, of Min. Sun. Iceland crystal, nearly -^ of an inch in thickness. 0 67 67 It stops 244 rays of heat, and 150 of light. 5 72* 71$ . . • 5f Greenish crown glass. 66% 71i...6|:5 = .741 Coach glass. ..7 fj8f 74'-. 5£ = .786 Min. Sun. Talc. Exper. 29. 0 67\ 67h 5 72 7l|...4j:8f= .861 Min. Sun. An easily calculable talc. Exper. 30. 0 50 50 5 54| 73|4|:3J = .816 44 = .756 It stops 139 rays of heat, and 90 of light. It stops 184 rays of heat, and 288 of light. Transmission of solar Heat through Glasses of the prismatic Colours. Exper. 31. Exper. 32. Exper. 33. Exper. 34. Exper. 35. Exper. 36. Min. 0 5 Min. 0 5 Min. 0 5 Min. 0 5 Min. 0 5 Min. 0 5 Sun 73 79k Sun. 68f 72i Sun. 671 74| Sun. 70k 744 Sun. 70£ 7H Sun. 67k 74i Very dark red glass. 73 744 ... 64 : 14 = This glass stops 800 rays of heat, and 9999, out of 10000 rays of light j which .200. amounts nearly to a total separation of light from heat. Dark- red glass. This red glass stops only 606 rays of 684 heat, and above 4999, out of 5000 70 . . . 4\ : 1* - = .394. rays of light. Orange glass. This orange-coloured glass stops 604 67^ rays of heat, which is nearly as much as 70|- . . . 6% : 2£ = .396. is stopped by the last red one ; but it stops only 779 rays of light. Yellow glass. 704 73 ... 3| : ty = .667. Pale-green glass. 70£ 71£...3|: 1| = .367. Dark-green glass. 67 h 68| ...6* -: 1 = .151. It stops 333 rays of heat, and 319 of light. It stops 633 rays of heat, and only 535 of light. This glass stops 849 rays of heat, and 949 of light. This accounts for its great use as a darkening glass for telescopes. VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 757 Min. Sun. Bluish-green glass. Exper. 37. 0 6of 6'9| It stops 768 rays of heat, and 769 of 5 76-f 71 ...7: 1|= .532. light. Min. Sun. Pale-blue glass. Exper. 38. 0 70| 70f The pale blue glass stops 812 rays 5 76% 7H . • • 6 : li = .188. of heat, and only 684 of light. Min. Sun. Dark-blue glass. Exper. 39. 0 71 71 The dark-blue glass stops only 362 5 76£ 743 . . . 5f : 3| = .638. rays of heat, and 801 of light. Min. Sun. Indigo glass. Expsr.40. 0 6l| ol| This glass stops 633 rays of heat, and 5 67i 64 . . . 6^ : 2£ = .367. 9997, out of 10000 rays of light. Min. Sun. Pale-indigo glass. Exper. 41. 0 62 62 It stops 532 rays of heat, and 978 of 5 67i 6'4| . . . 5f : 2| a .468. light. Min. Sun. Purple glass. Exper. 42. 0 613 613 It stops 583 rays of heat, and 993 of 5 673 64J...6:2£ = .417. light. Min. Sun. Violet glass. Exper. 43. 0 62 J 62 J It stops 489 rays of heat, and 955 of 5 68i 65} . . . 51 : 3 = .511. light. Transmission of Solar Heat through Liquids. — I took a small tube, 1-J- inch in diameter, fig. 16, and fixed a stop with a hole -§• inch wide at each end, on which a glass might be fastened, so as to confine liquids. The inner distance, or depth of the liquid, when confined, is 3 inches. Placing now the empty tube, with its 2 end glasses fixed, on the transmitting apparatus, I had as follows : Min. Sun. Empty tube, and two glasses. These glasses, with the intermediate Exper. 44. 0 53 53 air, stop 542 rays of heat, and 204 of 5 59 553 ... 6 : 23 = .458. light. Exper. 45. I filled the tube with well-water, Min. Sun. Well-water, and placed it on the transmitting apparatus. 0 52£ 52^ 5 58| 55 . . . 6£ : 2-£ = .442. Here 2 glasses, with water between them, stopped 558 rays of heat. The same glasses, and water, stop only 2 1 1 rays of light. If we were to deduct the effect of the empty machine, there would re- main, for the water to stop, only 16 rays of heat, and 7 of light ; but it cannot be safe to make this conclusion, as we are not sufficiently acquainted with the action of surfaces between the different mediums on the rays of heat and light ; I shall therefore only notice the effect of the compound. Exper. 46. I filled now the tube with sea-water, Min. Sun. Sea-water, taken from the head of the pier at Ramsgate, at 0 54| 54| high tide. 5 60 56 5£ : 13 = .318. The compound stops 682 rays of heat, and 288 of light. Min. Sun. Spirit of wine. Exper. 4,7. 0 51-| 514 The compound stops 612 rays of 2-f = .388. heat, and 224 of light. Min. Sun. Spirit of wine. 0 514 51| 5 573 54 ... 6- Min. Sun. Gin. 0 52 52 5 573 53|... 53 Min. Sun. Brandy. 0 56 56 5 60! 56-| ... 4 Exper. 48. 0 52 52 This compound stops 739 rays of l£ = .261. heat, and 626 of light. Exper. 49. 0 56 56 This stops 794 rays of heat, and 996 lj : 4= .206. rays of light. Other liquids have also been tried ; but the experiments having been attended with circumstances that demand a further investigation, they cannot now be given. Transmission of Solar Heat through Scattering Substances. Exper. 50. I rubbed one of the pieces of crown glass, mentioned in the 26th experiment, on fine emery laid on a plain brass tool, to make the surface of it rough, which, it is well known, will occasion 758 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. the transmitted light to be scattered in all directions. Supposing that it would have the same effect on heat, I tried the transmitting capacity of the glass, by exposing it with the rough side towards the Min. Sun. Crown glass. sun, over one of the transmitting holes of the 0 67 67 apparatus. 5 74 70| . . . 7 : 3| = .536. The glass so prepared stops 464 scattered rays of heat, and 854 of light. Now, as the same glass, in its polished state, transmitted 259 rays of heat, and 203 of light, the alteration produced in the texture of its surface acts very differently on these 2 principles ; occasioning an additional stoppage of only 205 rays of heat, but of 651 rays of light. Exper. 51. One of the pieces of coach glass, Min. Sun. Coach glass, mentioned in the 27th experiment, was prepared 0 663 66% in the same manner. 5 73 \ 69^ ... 7 : 3 = .429- It stops 571 scattered rays of heat, and 885 of light ; so that the fine scratches on its surface, made by the operation of emery, have again acted very differently on the rays of heat, and of light, occasioning an additional stoppage of 375 of the former, but of no less than 7 1 7 of the latter. Etpcr. 52. I took another of the pieces of crown Crown glass ; glass, mentioned in the 26th experiment, and Min. Sun. both sides rubbed on emery, rubbed both sides on emery. 0 69? 69^ 5 75\ 71} h. 6 : 2 = .333. The glass thus prepared, stops 667 scattered rays of heat, and 932 of light. Exper. 53. Another piece of coach glass, one of Coach glass ; those that were mentioned in the 27th experiment, Min. Sun. both sides rubbed on emery, was prepared in the same manner. 0 69% 69% 5 75$ 7lJ...6-L:lA = .265. It stops 735 scattered rays of heat, and 946 of light. Exper. 54. I placed now the coach glass, one side of which had been rubbed on emery, on the trans- mitting hole, and over it the crown glass prepared in the same manner, both with the rough side to- Crown glass, and. coach glass ; wards the sun ; but 2 slips of card were placed be- Min. Sun. one side of each rubbed on emery, tween the glasses, to keep them from touching 0 67 67 each other. 5 73*- 69 ... 6*- : 2 = .302. These glasses stop 698 scattered rays of heat, and 969 of light. Exper. 55. I placed now the coach glass, with Coach glass, and crown glass ; both sides rubbed on emery, on the transmitting Min. Sun. both sides of each rubbed on emery, hole, and over it the crown glass prepared in the 0 69% 69| same manner, with 2 slips of card between them, 5 75% 70^ . . . 6£ : I5 = .200. to prevent a contact. These glasses stop 800 scattered rays of heat, and 979 of light. rCrown glass ; the rough side to the sun. Exper. 56. I used now all the 4 glasses j placing Min. Sun. \ g^S5. ^gh on both sides. them as follows, and putting slips of card between V_Coach glass ; ditto, them, to prevent a contact. : 0 57% o7k 5 62I 58| ...54,: | = .146. These 4 glasses stop no more than 854 scattered rays of heat, and 99$ of light. Exper. 17. I used now a piece of glass of an olive colour, burnt into the glass, in the manner Min. Sun. Olive-coloured glass, that glasses are prepared for church windows, 0 69 69 which transmits only scattered light. 5 76% 70j . . . 7| : 1| = .l6l This glass stops 839 scattered rays of heat, and 984 of light. Min. Sun. Calcined talc. This substance stops 867 scattered Exper. 58. 0 5 If 51* rays of heat, and so much light that 5 55± 5 1-Z- . . . 3f : J- = . 1 33. the sun cannot be perceived through it.* Min. Sun. White paper. Exper. 59. 0 63 63 This substance stops 850 scattered 5 68 63| . . . 5 : I = .150. rays of heat, and 994 of light. Min. Sun. Linen. Exper. 60. 0 63 63 "White linen stops 916 scattered rays 5 69 63^. . . . 6 : £ = .0833. of heat, and 952 of light. * See the 175th experiment. Min. Sun. White persian. Exper. 6l. 0 70 70 5 76i 71^...6^:H=.240. Min. Sun. Black muslin. Exper. 62. 0 64g 64f 5 70 66| . . . 5| : H = .286. VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 759 This thin silk stops 760 scattered rays of heat, and 916 of light. This substance stops 714 scattered rays of heat, and 737 of light. Transmission of Terrestrial Flame-heat through various Substances. — My ap- paratus for the purpose of transmitting flame-heat is as follows. Fig. 1, pi. 14, a box 22 inches long, 5-^ broad, and 1^ deep, has a hole in the centre lTv inch in diameter, through which a wax candle, thick enough entirely to fill it, is to be put at the bottom ; the box being properly elevated for the purpose. There must be 2 lateral holes in the bottom, 2 inches long, and 1^ broad, one on each side of the candle, to supply it with a current of air, as otherwise it will not give a steady flame, which is absolutely necessary. At the distance of 1-^ inch from the candle, on each side, are 2 screens, 12 inches square, with a hole in each, 4 inch in diameter, through which the heat of the candle passes to the 2 thermometers, which are to be placed in opposite directions, one on each side of the table. Care must be taken to place them exactly at the same distance from the centre of the flame, as otherwise they will not receive equal quantities of heat. The scales, and their supports also, must be so kept out of the way of heat coming from the candle, that they may not scatter it back on the balls, but suffer all that is not intercepted by them to pass freely forwards in the box, and downwards, through openings cut in the bottom. Before the transmitting holes, between the 2 wooden screens, must be 2 covers of the same material, close to the openings, fig. 2 ; and it will be necessary to join these covers at the side, by a common handle, that they may be removed together, without disturbing any part of the apparatus, when the experiment is to begin. The glasses are to be put before the thermometer, close to the transmitting hole, by placing them on a small support below, while the upper part is held close to the screen by a light plummet suspended by a thread which is fastened on one side, and passes over the glass, to a hook on the other side. In making experiments, many attentions are necessary, such as, keeping the candle exactly to a certain height, that the brightest part of the flame may be just in the centre of the two transmitting holes : that the wick may be always straight, and not, by bending, approach nearer to one thermometer than to the other : that the wax-cup of the candle be kept clean, and never suffered to run over, &c. Be- fore, and now and then between, the observations also, the thermometers must be tried a few degrees, that it may be seen whether they act equally ; and the candle, during the time they cool down to the temperature, must be put out by an extin- guisher, large enough to rest on the bottom of the box, without touching any part of the wax. Many other precautions I need not mention, as they will soon be dis- covered by any one who may repeat such experiments. Min. Candle. Bluish-white glass. From this experiment we find, that Exper. 63. 0 591- $9h wtile me rays of the candle gave 3 5 62| 6'0-| . . . 3 : Vg = .375. degrees of heat to the thermometer 76o PHILOSOPHICAL TRANSACTIONS. [anno 1800. openly exposed to their action, the other thermometer, which received the same rays through the medium of the interposed glass, rose only 1% degrees. Hence we calculate, that this glass stops 625 rays of flame-heat, out of every thousand that fall on it. It stops only 86 rays of candle-light ; but this, having been referred to before, will not in future be repeated. Expcr. 64. Exper. 65. Exper. 66. Exper. 67. Exper. 68. Exper. 69. Exper. 70. Exper. 71. Exper. 72. Exper. 73. Exper. 74. Exper. 75. Exper. 76. Exper. 77. Exper. 78. Exper. 79- Exper. 80. Exper. 81 \ Min. Candle. Flint glass. 0 m 59| It stops 591 rays of flame-heat, and 5 624 60| . . . 2| : 1* = .409. Min. Candle. Crown glass. 0 59i m It stops 636 rays of flame-beat. 5 624- 60*...2|: 1 = .364. Min. Candle. Coach glass. 0 60 60* 5 63 62 . ..3 : 1*=.542. Its tops 458 rays of flame-heat. Min. Candle. Iceland crystal. 0 58j 58| 5 62* 60* . .3|:1* : = .484. It stops 5l6 rays of flame-heat. Min. Candle. Calcinable talc. 0 5*f 58* This substance stops only 375 rays of 5 6ll- 60| ...3: 1* = .625. flame-heat. Min. Candle. Very dark red glass. 0 604 60J- 5 63^ 6l| ...2| : 1 = : .36i. This glass stops 636 rays of flame-heat. Min. Candle. Dark red glass. 0 60f 60| 5 63* 61*. ..24:1* = .474. It stops 526 rays of flame-heat. Min. Candle. Orange glass. 0 60J 6o| 5 631 61J...3H l* = AW. It stops 560 rays of flame-heat. Min. Candle. Yellow glass. 0 60| 60* 5 ftf 6l*...3:l£ = .417. It stops 583 rays of flame-heat. Min. Candle. Pale-green glass. 0 60* 60* 5 63* 62|...3:lJ = .500. It stops 500 rays of flame-heat. Min. Candle. Dark-green glass. 0 61* 61* 5 64 6l|...25:| = : .261. It stops 739 rays of flame-heat. Min. Candle. Bluish-green glass. 0 61* 61* 5 64 62*... 2*: 1 = = .348. It stops 652 rays of flame-heat. Min. Candle. Pale-blue glass. 0 6l| fci 5 641 62$... 2*: 1* = .391. It stops 609 rays of flame-heat. Min. Candle. Dark-blue glass. 0 61* 6l| 5 6\\ 62| . . . 2| : 1 = : .381. It stops 619 rays of flame-heat. Min. Candle. Indigo glass. 0 6l7g 61 \ 5 651 63 ... 3 J : 1* = = .321. It stops 679 rays of flame-heat. Min. Candle. Pale indigo glass. 0 62 J 62* 5 64| 63J...24: 1* = .429- It stops 571 rays of flame-heat. Min. Candle. Purple glass. 0 6H 6\\ 5 65 634... 3fr: \\ = .480. It stops 520 rays of flame-heat. Min. Candle. Violet glass. 0 5 595 631 59* 614 ... 3A : li = .500. It stops 500 rays of flame-heat. VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 76l Min. Candle. Exper. 82. 60 63f Min. Candle. Exper. 83. Exper. 84. Exper. 85. Exper. 86. Exper. 87. 0 5 Min. 0 5 Min. 0 5 Min. 0 5 Min. 0 5 59| 63| Candle. 59| 63 Candle. 591 63 Candle. 55$ 59 Candle. 551 59i Crown glass 5 one side rubbed on emery ; the rough side exposed. 60 This glass, so prepared, stops 741 scat- 601 . . . 3f : I = .259. tered rays of flame-heat. Coach glass j one side rubbed on emery 3 the rough side exposed. m 604 . . . 3| : 1 J = .333. It stops 667 scattered rays of flame-heat. Crown glasss ; both sides rubbed on emery. 59f It stops 6 i 5 scattered rays 61 ... 3J : 1| = .385. of flame-heat. Coach glass ; both sides rubbed on emery. Min. Candle. Exper. 88. 0 5 Min. Exper. 89. 0 5 Min. Exper. 90. 0 5 Min. Exper. 91. 0 5 Min. -Erper. 92. 0 Exper. 93. Min. 0 5 56| 594 Candle. 60 63 Candle. 604 Candle. 574 61 Candle. 57i 6oh Candle. 57| 604r 59% 6(>§ . . . 3-t : 1 = .320. /Crown glass. \ One side of each rubbed \ Coach glass. / on emery. 551 56| . . . 3-L : 1 = .280. / Crown glass. \ Both sides of each rubbed \ Coach glass./ on emery. 55-| 57 . . . 34 : 4 = .333. {Crown glass ; the rough side to the candle. Coach glass ; ditto. Crown glass ; rough on both sides. Coach glass ; ditto. S6\ 57i... 24: 4 = .130. Olive-colour, burnt in glass. 60 * It stops 680 scattered rays of flame-heat. These glasses stop 720 scattered rays of flame-heat. These glasses stop 667 rays of flame-heat. These four glasses stop 87"0 scat- tered rays of flame-heat. 604. ..3 White paper. 571 57±...3 Linen. 571 This glass stops 79% scattered rays of 4 = .208. flame-heat. This substance stops 792 scattered rays of 5 = .208. flame-heat. 58£ ... 34 : 14 = .310. It stops 690 scattered rays of flame-heat. White persian. 57 584. ..34 Black muslin. 57| 59 ... 24 : 14 = .407. It stops 593 scattered rays of flame-heat. = .435. It stops 565 scattered rays of flame-heat. Transmission of the Solar Heat which is of an Equal Refrangibility with Red Prismatic Rays. — The apparatus which I have used for transmitting prismatic rays, is of the same construction as that which has already been described under the head of direct solar transmissions ; but here the holes in the top of the box are only 2 inches from each other, and no more than 4-ths in diameter, fig. \*J, pi. 13. On the face of the box are drawn two parallel lines, also 4-ths of an inch distant from each other, and inclosing the transmitting holes : they serve as a di- rection by which to keep any required colour to fall equally on both holes. The distance at which the box is to be placed from the prism, must be such as will allow the rays to diverge sufficiently for the required colour to fill the transmitting holes ; and the balls of the thermometers placed under them ought to be less than these holes, that the projected rays may pass around them, and show their proper adjustment. The diameters of mine, used for this purpose, are 2\ tenths of an inch. VOL. XVIII. 5 E ;6'2 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. Exper. Q4. — I placed my apparatus at 5 feet from the prism, and so as to cause the red-making rays to fall be Min. Red rays. Bluish-white glass. Therm. A. Them. B. tween the parallel lines in order to find what heat-mak- 0 75-f 754 in°- rays would come to the thermometer along with them. 5 77-f- 764 . . . 2 : 14 = .625. "From this experiment it appears, that when 1000 red-making rays fall on each transmitting hole, 375 of them, if they also be the heat-making rays, are stopped by the bluish-white glass which covers one of these holes ; or, what requires no other proof than the experiment itself, that 375 rays of heat, of the same refrangibility with the red rays, are intercepted by this glass. Exper. 95. Eiper. 9$ Exper. 97. Exper. 98. Exper. 99 Exper. Exper. Eiper. Exper. Exper. Exper. Exper. Min. 0 5 Min. 0 5 Min. 0 5 Min. 0 5 Min. 0 5 Min. 100. 0 5 Min. 101. 0 5 Min. 102. 0 5 Min. 103. 0 5 Min. 104. 0 5 Min. 105. 0 5 Red rays. 75| 111 Red rays. 7^ 78 Red rays. 541 55-1 Red rays. 7H 78 Red rays. 51| 534 Red rays. m 78i Red rays. 75 77 Red rays 75$ 764 Red rays. 74| 76-f Red rays. 68| 70\ Red rays. 69 704 Min. Red rays. 106. 0 694 5 70| Min. Red rays. Exper. Exper. 107. 0 5 Min. 108. 0 5 Min. Exper. 109. 0 5 Min. Exper. 110. 0 5 Min. Exper. ill. 0 5 67 68| Red rays. 68 J rot Red rays. 69 71 Red rays. 564 58] Red rays. 574 594 Flint glass. 75± tft,..ll Crown glass. 75-1 77i...2i: l£ = .706 Coach glass. 53| 54f . . . 14 Iceland crystal. 75| 77J... I*: 1| =-800 Calcinable talc. 514 52i . . . H : Dark red glass. 764 77i • • • H : I = -308. Orange glass. 7H 75f ...2: Yellowglass. 75 75f...l| Pale green glass. 74i 75... 2^:4 = .412. Dark-green glass. 6si 694 ... 1| : 4= .214. Bluish- green glass. 684 69i...H: Pale-blue glass. 69| 694. .-14 = Dark-blue glass. 674 6*4... 1|:14= .929. Indigo glass. 6*4 69}.. • 2: 14 = .633. Pale indigo glass. 6H • 70 ... 2 : 14 = .687. Purple glass. 56 574 •- • 24 Violet glass. 57 58i... 14 This glass stops only 143 rays of heat which are of the same refrangibility with the red rays. This glass stops 294 rays of the same sort of heat. 1 = .800. It stops 200 rays of the same sort of heat. This substance stops 200 rays of the same sort of heat. 14 = .867. It stops 133 rays of the same sort of heat. This glass stops 692 rays sort of heat. of the same 1 = .500. It stops 500 rays of the same sort of heat. 4 = .583. It stops 417 rays of the same sort of heat. It stops 588 rays of the same sort of heat It stops 786 rays of the same sort of heat. I = .538. It stops 46'2 rays of the same sort of heat. = .300. It stops 700 rays of the same sort of heat. This glass stops only 71 rays of the same sort of heat. It stops 367 rays of the same sort of heat It stops 3 1 3 rays of the same sort of heat. 1 4 = .556. It stops 444 rays of the same sort of heat. 11 b .600. Itstops 400 rays of the sm sort of heat. Min. Red rays. Exper. 112. 0 5 52 Min. Red rays. Exper. 113. 0 5 53| 55i Exper. Min. 114. 0 3 Red rays. 304 52| Exper. Min. 115. 0 5 Red rays. 34i 55| Exper. Min. li6. 0 5 Red rays. 51* 53| VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 763 Crown glass ; one side rubbed on emery, rough side exposed. 49 This glass, so prepared, stops 389 scat- 50| . . . 2 J :l-§ = .611. tered rays of the same sort of heat. Coach glass ; one side rubbed on emery, rough side exposed. 52-| It stops 500 scattered rays of 33 J . . . 1| : £ = .500. the same sort of heat. Crown glass 5 both sides rubbed on emery. 494 It stops 47 1 scattered rays of 5 1 ... 2\ : 14 = .529. the same sort of heat. Coach glass j both sides rubbed on emery. 53f It stops 833 scattered rays of the 34 . . . 1 £ : i = . 16"7- same sort of heat. Calcined talc. 50£ This substance stops 7tf scattered rays 5H . . • 24 : 4 = .263. of the same sort of heat. Transmission of Fire- Heat through various Substances. — When the same fire is to give an equal heat to two thermometers, at some short distance from each other, it becomes highly necessary that there should be a place of considerable dimensions in its centre, where it may burn with equal glow, and without flame or smoke. To obtain this, I used a grate 1Q inches broad, and 84 high, having only 3 bars, which divide the fire into 3 large openings. In the centre of the middle one of these, when the grate is well filled with large coals or coke, we may, with proper management, keep up the required equality of radiance. The apparatus I have used is of the following construction. A screen of wood, fig. 3. pi. 14, 3 feet 6 inches high, and 3 feet broad, lined towards the fire with plates of iron, has two holes, \ of an inch in diameter, and at the distance of 24- inches from each other, one on each side of the middle of the screen, and of a height that will answer to the centre of the fire. 24- inches under the centre of the holes is a shelf, about 22 inches long and 4 broad, on which are placed two thermometers, in opposite directions fixed on proper stands, to bring the balls, quite disengaged from the scales, directly 2 inches behind the transmitting holes. A small thin wooden partition is run up between the thermometers, to prevent the heat transmitted through one hole from coming to the thermometer belonging to the other. The screen is fixed on a light frame, which fits exactly into the opening of the front of the marble chimney-piece ; and the ends of the frame are of a length which, when the screen is placed before the fire, will just bring the transmitting holes to be 64- inches from the front bars of the grate. A large wooden cover, also plated with iron, shuts up the transmitting holes on the side next to the fire ; but may be drawn up by a string on the outside so as to open them when required. Two assistant thermometers are placed on proper stands to bring their balls to the same distance from the screen as those which re- ceive the heat of the fire ; but removed sideways as far as necessary, to put them out of the reach of any rays that pass obliquely through the transmitting holes. They are to indicate any change of temperature that may take place du- 5 e 2 764 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. ring the time of the experiment : for, notwithstanding the largeness of the screen, some heat will find its way round and over it ; and this acting as a general cause, its effect must be allowed for. Exper. 117. Having tried the apparatus sufficiently to find that the thermometers exposed to the transmitting holes would generally receive 20 or more degrees of heat, without differing more than sometimes \ or at most J of a degree, I Min. Fire. Bluish-white glass. now placed the bluish- white glass of the 24th experiment on a 0 66 66 support prepared for the purpose, so as closely to cover one of 5 86 71 ... 20 : 5 = .250. the transmitting holes. A small spring, moveable on its cen- tre, is always turned against the upper part of the transmit- ting glasses, to keep them in their situation. This glass stops 750 rays of fire-heat. By looking through it, at the same place in the fire, after the screen was removed, in order to cool the apparatus for the next experiment, I found that this glass can hardly be said to stop any of the light of the fire. Min. Fire. Flint glass. Exper. 118. 0 67 67 5 87 72 . . 20 : 5 = .250. It stops 750 rays of fire-heat. Min. Fire. Crown glass. Exper. 119. 0 67 67 5 86| 7*h • • • 191 : H — .278. It stops 722 rays of fire-heat. Min. Fire. Coach glass. Exper. 120. 0 67h W\ 5 86| 73 . . • 191 : H = »28?>. It stops 71 i rays of fire-heat. Min. Fire. Iceland crystal. Exper. 121. 0 6*8 68 5 90h 73£ . . . 22£ : 5\ = .244. This substance stops 756 rays of fire-heat. Exper. 122. I took now the piece of talc used in the 30th experiment, and, . placing it over the transmitting hole, I had the following result. But, as the unexpected event of a calcination, which took place, was attended with circumstances that ought to be noticed, I shall in- stead of the usual abridgement of the experiments, give this at full length. This substance stops 713 rays of fire heat. I am now to point out the singularity of this experiment ; which consists, as we may see by the above register of it, in the apparently regular continuance of its power of transmitting heat, while its capacity of transmitting light was totally de- stroyed. For, when I placed this piece of talc over the hole in the screen, it was extremely transparent, as this substance is generally known to be ; and yet, when the experiment was over, it appeared of a beautiful white colour ; and its power of transmitting light was so totally destroyed,that even the sun in the meridian could not be perceived through it. Now, had the power of transmitting heat through this substance been really uniform during all the 5 minutes, it would have been quite a new phenomenon ; as all my experiments are attended with a regular increase of it ; but since by calcination, the talc lost much of its transmitting power, we may easily account for this unexpected regularity. Fire. Very dark red glass. Exper. 123. 66 06 894 75 ... 23 4 : 9 = 3b7. This glass stops 6l3 rays of fire-heat. Min. Fire Dark-red glass. This glass, which stops 999-3 rays of Exper. 124. 0 67 67 candle-light, stops only 573 rays of fire- 5 92g 78 . . . 25| : 1 1 = .427. heat ; whereas my piece of thick flint glass, which stops no more than 91 rays of that light, stops no less than 750 of fire-heat. It does not in. 0 Fire. Therm. D. 65 Talc. Therm. C. 65 1 2 3 4 5 72 77 80| 83 85 67 ... 7 ftj ... 12 69h... 15| 70 ...18 70| . . . 20 : : 2 sfe .289. 1 3| = .281. : 4| = .290. : 5 = .278. 5| = .287. VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 7§5 appear, by looking through these glasses, that there is a difference in their disposition to transmit candle- light or fire-light. Min. Fire. Orange glass. Exper. 125. 0 66" 66 5 80 71 ... 14 : 5 = .357. It stops 643 rays of fire-heat. Min. Fire. Yellow glass. This experiment be- Exper. 126. 0 6l£ 6lJ ing made early in the 5 83 68 1 ... 21 : 7f • cor. - 1£° . 20| : 6£ — .315 morning, before the temperature of the room was come to its usual height, the assistant thermometers showed a gradual ris- ing of 1^ degree in the 5 minutes : they are in general very steady. The glass stops 685 rays of fire-heat. Min. Fire. Pale green glass. Exper. 127. 0 65% 65| 5 85 7 If . . . 19h ■■ 6 = .312 It stops 688 rays of fire-heat. Min. Fire. Dark green glass. Exper. 128. 0 68 68 5 88f 73*- ...20 g : 5| cor. - 4°= 255. It stops 745 rays of fire-heat. Min. Fire. Bluish green glass. Exper. 129- 0 6'8£ 68£ 5 87 74 1- . . . 18-J. : 5 J = .304. It stops 696 rays of fire-heat. Min. Fire. Pale blue glass. Exper. 130. 0 68£ 68 5 S6£ 73| ... 17| : 5| = .324. It stops 676 rays of fire-heat. Min. Fire. Dark blue glass. Exper. 131. 0 67 67 5 84-| 73 ... 17|: 6. cor. -1°= .296. It stops 704 rays of fire-heat. Min. Fire. Indigo glass. Exper. 132. 0 69% 69I 5 85-a 73| .. . 16l : 4| = .279- It stops 721 rays of fire-heat. Min. Fire. Pale indigo glass. Exper. 133. 0 67^ 67k 5 85-1 74 . . . 18| : 6^ . cor. - \° = .345. It stops 655 rays of fire-heat. Min. Fire. Purple glass. Exper. 134. 0 69 69 5 83 73^... 14 : \\ = .321. It stops 679 rays of fire-heat. Min. Fire. Violet glass. Exper. 135. 0 66% 66'| 5 86 j 74} . . . 20 : 7| = -385. It stops 615 rays of fire-heat. Min. Fire. Crown glass ; one side rubbed on emery. Exper. 136. 0 67i 67% This glass, so prepared, stops 723 scat- 5 89| 73| . . . 22i : 6\ = .277. tered rays of fire-heat. Min. Fire. Coach glass ; one side rubbed on emery. Exper. 137. 0 68 67 1 5 87^ 72\ . . . 19^ : 4-| = .242. It stops 758 scattered rays of fire-heat. -— ' Min. Fire. Crown glass ; both sides rubbed on emery. Exper. 138. 0 68| 68 5 92f 73 . . . 23! : 5 = -2°9. It stops 791 scattered rays of fire-heat. Min. Fire. Coach glass ; both sides rubbed on emeiy. Exper. 139. 0 67 67 It stops 854 scattered rays of 5 88 701 ...21 :3|. cor. - |° = .146. fire-heat. M'n Vrt* $ Crown glass. \ One side of each rubbed lVIin. fire. \ Coach glass./ on emery. Exper. 140. 0 66 66 These glasses stop 849 scat- 5 86 69i ... 20 : 31 . cor . - 1 ° = . 1 5 1 . tered rays of fire-heat. Min PW / Crown glass. \ Both sides of each rubbed iviin. rire. \ Coach glass./ on emery. Exper. 141. 0 66| 66| These glasses stop 897 scat- 5 83| 68| . . . 17 : If = .103. tered rays of fire-heat. M. The 4 glasses of the 2 preceding expe- lYLin. pure. riments put together. Exper. 142. 0 66 66 , These 4 glasses stop 902 scat- 5 80 67-f ... 14 : 1-f = .098. tered rays of fire- heat. 766 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800, Exper, Min. 143. 0 5 Fire. 63$ 85f Olive colour, burnt into glass. 63% 67% ...22:3f .cor.— J° = . Exper. Min. 144. 0 5 Fire. 66% 83h Paper. 66\ 68 ... 17: 1| = .0882. Exper. Min. 145. 0 5 Fire. 63| 84| Linen. 63| 67 ...21:3£.car.— 1$° = Exper. Min. 146. 0 5 Fire. 8H White persian. 65$ 68-f... 15^: 2-| =.171. Exper. Min. 147. o 5 Fire. 66 82£ Black muslin. 66 70£ . . . 16| : 4i . cor. + h° = This glass stops 849 scattered 151. rays of fire-heat. This substance stops 912 scattered rays of fire-heat; it was turned a little yellow by the exposure. This substance stops 9 10 scat- .0897. tered rays of fire-heat. This substance stops 829 scat- tered rays of fire-heat. This substance stops 706 scat- .294. tered rays of fire-heat. Transmission of the Invisible Rays of Solar Heat. — The same apparatus which I have used for the transmission of coloured prismatic rays, fig. 17, pi. 13, will also do for the invisible part of the heat spectrum: it is only required to add 2 or 3 more parallel lines, -±$ of an inch from each other, below the two which inclose the transmitting holes, in order to use them for directing the invisible rays of heat, by the position of the visible rays of light, to fall on the place required for coming to the thermometers. This glass stops only 71 invi- sible rays of heat. This glass stops no invisible rays of heat Min. Invis. rays. Bluish white glass. Exper. 148. 0 48 47 5 491 484... If: If =.929. Min. Invis. rays. Flint glass. Exper. 149. 0 50| 491 5 52 51-L...1J: 1| = 1.000. Min. Invis. rays. Crown glass. Exper. 150. 0 50| 49| • 5 5}i 50J...1$:H=.818. Min. Invis. rays. Coach glass. Exper. 151. 0 54| 531 5 55-| 54f...l:| = .857. Min. Invis. rays. Calcinable talc. Exper. 152. 0 m 50| 5 52| 5LJ...l!:li = .750. Min. Invis. rays. Dark red glass. Exper. 153. 0 474 46| 5 48-| 47* ... 1 : 1 = 1.000. looking at the sun thi rough a telescope, when red darkening glasses Min. Invis. rays. Orange glass. xper . 154. 0 51-3. 51 5 53 52 . :. 1| : 1 sb .727. Min. Invis. rays. Yellow glass. Exper. 155. 0 51| 51 5 53 52 . . . lj : 1 =s .800. Min. Invis. rays. Pale green glass. Exper. 156. 0 «* 514 5 52| 511 . . . 1 : i = .625. Min. Invis. rays. Dark green glass. Exper. 157. 0 51* 51| 5 52i 52 . . . 1 : I = .500. Min. Invis. rays. Bluish green glass. Exper. 158. 0 53 52j 5 54j 52j . . . \\ : I = .200. It stops 1S2 invisible rays of heat. It stops 143 invisible rays of heat. This substance stops 250 invisible rays of heat. This glass stops no invisible rays of heat. This accounts for the strong sensation of heat felt by the eye, in are used. It stops 273 invisible rays of heat. It stops 200 invisible rays of heat. It stops 375 invisible rays of heat. It stops 500 invisible rays of heat. It stops 800 invisible rays of heat. VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 767 Min. Invis. rays. Pale blue glass. Exper. 159. 0 5H 5l£ 5 53-jj- 51-|- . . . \\ : -f == .417. It stops 583 invisible rays of heat. Min. Invis. rays. Dark blue glass. Exper. 160. 0 52-L 5 14 5 52-| 52| ... I : i = .833. It stops 167 invisible rays of heat. Min. Invis. rays. Indigo glass. Exper. 161. 0 52| 52| 5 54f 53 . . . I5 : f = .500. It stops 500 invisible rays of heat. Min. Invis. rays. Pale indigo glass. Exper. 162. 0 52| 52-L 5 53f 52i ... 1 : I = .750. It stops 250 invisible rays of heat. Min. Invis. rays. Purple glass. Exper. 163. 0 5l£ 50-f. 5 52-g- 51-3. . . . 1-J : 1 = .727. It stops 273 invisible rays of heat. Min. Invis. rays. Violet glass. Exper. 164. 0 53£ 52f 5 54J 53 l . . . 1 : £ = .750. It stops 250 invisible rays of heat. ,,. T . Crown glass: one side rubbed on emery, Min. Invis. rays. P .,' , J> * rough side exposed- Exper. 165. 0 49| 48£ This glass, so prepared, stops 6*00 5 50| 49| . . . I5 : \ — .400. scattered invisible rays of heat. ,.. , . Coach glass; one side rubbed on Mm. Invis. rays. u -j j 1 emery, rough side exposed. Exper, 166. 0 54 53-f It stops 500 scattered invisible rays 5 55\ 54 . . . l£ : -I = .500. of heat. Min. Invis. rays. Crown glass ; both sides rubbed on emery. Exper. 167. 0 50 49^ It stops 600 scattered invisible rays 5 5lJ 49| . . . 14 : \ = .400. of heat. Min. Invis. rays. Coach glass 3 both sides rubbed on emery. Exper. 168. 0 54| 54 £ It stops 714 scattered invisible rays 5 55% 54f . . . i : J = .286. of heat. Min. Invis. rays. Calcined talc. Exper. 169. 0 51| 50^ This substance stops 889 scattered 5 53 51 . . . 1£ : •£■ == .111. invisible rays of heat. Transmission of Invisible Terrestrial Heat. — This is perhaps the most extensive and most interesting of all the articles we have to investigate. Dark heat is with us the most common of all; and its passage from one body into another, is what it highly concerns us to trace out. The slightest change of temperature denotes the motion of invisible heat ; and if we could be fully informed about the method of its transmission, much light would be thrown on what now still remains a mys- terious subject. It must be remembered, that in the following experiments, I only mean to point out the transmission of such dark heat as I have before proved to consist of rays, without inquiring whether there be any other than such existing. My apparatus for these experiments is as follows. A box, fig. 4, pi. 14, 12 inches long, 54- broad, and 3 deep, has a partition throughout its whole length, which divides it into 2 parts. At one end of each division is a hole ^ inch in dia- meter; and each division contains a thermometer, with its ball exposed to the hole, and at 1 inch distance from the outside of the box. Four inches of the box, next to the holes are covered ; the rest is open. In the front of it is a narrow slip of wood, on which may rest any glass to be tried; and it is held close to the wood at the top, by a small spring applied against it. Two screws are planted on the front, 768 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. one on each side, which may be drawn out or screwed in, by way of accurately adjusting the distance of the thermometer' from the line of action. In order to procure invisible terrestrial heat, I have tried many different ways, but a stove is the most commodious of them. Iron is a substance that transmits invisible heat very readily; while, at the same time, it will most effectually intercept every visible ray of the fire by which it is heated, provided that be not carried to any great ex- cess. I therefore made use of an iron stove, fig. 5, having 4 flat sides, and being constructed so as to exclude all appearance of light. I had it placed close to a wall, that the pipe which conveys away smoke might not scatter heat into the room. The thermometer box, when experiments are to be made, is to be put into an arrangement of 12 bricks, placed on a stand, with casters: these bricks, fig. 6, when the stand is rolled close to the stove, which must not be done till an experi- ment is to begin, form an inclosure, just fitting round the sides, bottom, and covered part of the top of the thermometer box, and completely guard it against the heat of the stove. The box is then shoved into the brick opening, close to the iron side of the stove, where the two front screws, coming into contact with the iron plate, give the thermometers their proper distance; which, in the following experiments, has been such as to bring the most advanced part of the balls to 1^ inch from the hot iron. It will be necessary to remark, that on calculating the transmissions for the 5th minute, I found that it would not be doing justice to the stopping power of the glasses, to take so long a time; for, notwithstanding the use of brickwork, and the precaution I had taken, of having two sets of it, that one might be cooling while the other was employed, and though neither of them was ever very hot, yet I found that so much heat came to the box, that when it was taken out of the bricks, in order to be cooled, the thermometers continued still to rise, at an average, about 2° higher than they were. I have therefore now taken the 3d minute, as a much safer way to come at the truth. This glass stops 700 invisible rays of heat. It stops 533 invisible rays of heat. It stops 783 invisible rays of heat. It stops 625 invisible rays of heat. This substance stops 726 invisible rays of heat. At the end of 5 minutes, when the box was taken out of the bricks, the talc was perfectly turned into a scattering sub- stance; as such, it stops 5^6 scattered invisible ravs of heat. The sun cannot be seen through it; but this I find is chiefly owing to its scattering disposition. It stops however 997 scattered rays oi light. Min. Stove. Bluish white glass. Exper. 170. 0 3 56 591 55| 56| ... 3| : l\ — .300. Exper. 171. Min. 0 3 Stove. 53| 55i Flint glass. 53£ 5H.-.H:i = .467. Min. Stove. Crown glass. Exper. 172. 0 3 50£ 53* 50^ 5H...2-|:|=.217. Min. Stove. Coach glass. Exper. 173. 0 3 50£ 52£ 50£ 5l| ...2: £ = .375. Min. Stove. Iceland crystal. Exper. 174. 0 3 47 54| 46| 48f . . . 7| : 2i = .274. Min. Stove. Calculable talc. Exper. 175. , 0 3 51 57h 5H 54| . • • 61 = H = -404. VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 769 Min. Stove. Dark red glass. . Evper. 176. 0 58 58 3 64£ 6o£ . . . 6£ : * of heat. flame. Fire. . 700 Pale-indigo .571 655. . 533 Purple 520 679. . 783 Violet 500 6l5. . 625 Crown glass, one side rough. . 741 .... 723. . 726 Coach glass, ditto 667. . . . 758. , .615 Crown glass, both sides rough 6l 5. ... 791. Coach glass, both 680 854 . 630 The two last but two, together 20. . . . 849 . 524 The two last together 667 897 .531 The four last together 87 0 902 . 632 Olive-colour, burnt in glass . 792. . . . 849. . 700 White paper 792 912. . 556 White linen 690. . . . 910. . 548 White persian 593 82Q . 632 Black muslin 565 706 .659 Inriiiblt heat. ..700 .730 .684 .775 .741 .833 .769 .636 .535 .457 782 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. Let us now examine what information we may draw from the facts which are recorded in this table. The first that must occur is, that a candle which emits light, is also a copious source of invisible heat. If this should seem to require a proof I give it as follows. That the candle emits heat along with light, the ther- mometer has ascertained ; and, that a considerable share of this at least must be invisible, follows from comparing together the quantity of light and heat which , are stopped by different glasses. The bluish-white one, for instance, stops 86 rays of light, and 625 of heat. Hence, if only visible rays of heat came from the candle, a glass stopping more light, as for instance the dark-red glass, which stops 999.8, ought to stop all heat whatever ; but the fact is, that it even stops 100 rays less than the former. This instance alone shows plainly, that the exist- ence of invisible terrestrial heat in the flame of a candle, is proved; while, on the contrary, heat derived from rays that are visible, remains yet to be established, by those who would maintain that there are any such. But, for the sake of argu- ment, let us endeavour to explain how visible rays of heat may be reconciled with the contents of our 6th table. " Now though we must allow," it may be said, " that there is a certain quantity of candle-heat which cannot be seen, we are however at liberty to assign any ratio that this may bear to its visible heat-rays. Let us therefore begin with the bluish-white glass, and make the most favourable supposition we can, in order to explain its phenomena. Visible or invisible, it stops 625 rays of heat, and also 86 of light. Now, as in the last column of the table we have likewise the proportional quantity of invisible heat it intercepts, which is 700 out of 1000, we may surmise that the 914 rays of light, together with the 300 of the invisible rays which are transmitted, make up the 375 rays of heat which pass through the glass. . Hence, by algebra, we have the number of invisible heat-rays 878, and the number of the visible ones 122. Then, to try how this will answer, if 1000 rays of light give 122 of heat, 80 will give 10; and if out of 1000 invisible rays 700 be stopped, 878 will give 6l5 to be inter- cepted. The sum of these will be 625, which is exactly the number pointed out by our table." Now this being a fair solution of one instance, let us see how it will agree with some others. Before proceeding however, I cannot help remarking, that the supporters of visible heat-rays must feel themselves already considerably confined, as our present argument will not allow them more than 122 of such rays out of 1000. Now, if the assumption that terrestrial heat is owing to a mixture of visible and invisible rays, in the proportion of 122 of the former to 878 of the latter, be well-founded, it ought to explain every other phenomenon collected in our table. The purple- coloured glass stops 993 rays of light, which, according to our present hypothesis, should stop 121 rays of heat: it also stops 730 invisible rays, which will give 641 rays of intercepted heat; therefore this glass should stop 762 rays of heat, out of every 1 000 that come from a candle ; but from our table we find that it stops no more than 520, so that 242 rays cannot be accounted for. The glass VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 783 with an olive colour burnt into it, stops 984 rays of light, or 120 of heat, and 637 invisible rays, or 559 °f heat. The sum is 679 which that glass should stop, but it stops actually 79*2 ; so that, as in the foregoing instance we had a deficiency of 242 rays, we now have an excess of 113; which plainly shows, that no hypo- thesis of any other proportion between the visible and invisible rays of heat can answer to both cases; and that consequently, not only the present, but every other assumption of this kind, must be given up as erroneous. I shall not enlarge on these arguments, as I take them to be sufficiently clear to decide the question we have had under consideration. I also forbear going into an examination of what our 6th article, which treats of scattered heat, might afford, in addition to the former arguments. It may just be remarked, that the 211th experiment points out a black object, which scatters more heat than a white one ; while the case, as to light, is well known to be the reverse. The 21Qth experi- ment also shows, that the scattering of heat of gold paper is considerably inferior to that of black velvet ; whereas a contrary difference, of a very great extent, is pointed out between these two substances ; for black velvet scatters only 7 rays of light, while the scattering of gold paper amounts to more than 124000. I am well aware that this difference will perhaps admit of a solution on other principles than those which relate merely to the laws of scattering, and confess that many experiments are still wanting to complete this article, which cannot now be given ; but as this paper is already of an unusual length, I ought rather to apologize for having given so much, than for not giving more. Table of the Transmission of Terrestrial Scattered Light through various Sub- stances ; with a short Account of the Method by which the Results contained in this Table have been obtained. — The transmissions here delivered are called terrestrial and scattered, to distinguish them from others, which are direct and solar; and, in the use I have made of them in the foregoing paper, it has been supposed that light-making rays, whether direct and solar, or scattered and terrestrial, are trans- mitted in the same manner ; or that the difference, if there be any, may not be considerable enough to affect my arguments materially. In this I have only fol- lowed the example of an eminent optical writer, who does not so much as hint at a possibility that there may be a difference. Before describing my apparatus, I ought to mention that it is entirely founded on the principles of the author now alluded to,* and that no other difficulty occurs in the execution of his plan, than how to guard properly against the scatterings of the lamp : for the light which this will throw on every object, must not be permitted to come to the vanes; since these scatterings cannot remain equal on both vanes, when one of them is move- able. In the following construction, the greatest difficulties have been removed ; and a desirable consistency in the results of the experiments, when often repeated, has now been obtained. * See Traite d'Optique, page 16, fig. 5 j Ouvrage posthume de M. Bouguer.— Orig. 784 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. A board about 14 feet long, and 6 inches broad, fig. 7, pi. 14, has 2 slips of deal, an inch square, fastened on the 2 sides: these make a groove, for 2 short pieces, to slide in, backwards and forwards. The 2 sliding pieces, figs. 8 and 9, carry each a small board or vane; one towards the right, the other towards the left; but so as to meet in the middle, and apparently to make but one when placed side by side. The vanes are covered with a piece of fair white paper, which is to reflect, or rather to scatter light in every direction. To one end of the board is fixed a circular piece of wood, with an opening in it, which is afterwards to be shut up by a small moveable piece, fig. 10, intended for placing the transmitting objects on. This moveable piece contains 2 holes, at the distance of 14- inch from centre to centre, and a inch in diameter each. Against the circular wooden screen, and close over the opening in it, is placed a lantern containing a lamp; fig. 11. Its construction is such as to admit a current of air to feed the flame from below, by means of a false bottom, and to let it out by a covered roof; and the whole of the light, by the usual contrivance of dark lanterns, is thus kept within, so as to leave the room in perfect darkness. In the front, that is towards the vanes, the lantern has a sliding door of tin-plate, in which there is a parallelogrammic hole, covered with a spout 5 inches long, of the same shape. Two or 3 such doors, with dif- ferent spouts and openings, will be required to be put in, according to the ex- periments to be made; but the first will do for most of them. A narrow arm is fastened to the long board, which advances about 3 feet beyond the screen, and carries a circular piece of pasteboard, that has an adjustable hole in the centre, through which the observer is to look when the experiments are to be made. At the further end of the long board is a pulley, over which a string, fastened to the back of the slider that carries one of the vanes, is made to pass. This string returns under the bottom of the long board, towards the other end, where, close to the observer, another pulley is fixed; and, after going also over this pulley, it returns at the top of the board, to the front of the same vane, to which the other end of it is fastened at the back. By pulling the string either way, the observer may bring forward the moveable vane, or draw it back, at plea- sure. At the side of the long board is a scale of tens of inches, numbered from the place of the flame of the lamp, O, 10, 20, 30, 40, and so on to J 60. A pair of compasses being applied from the last 10 towards the vane, ascertains its distance from the flame, to as great an accuracy as may be required. When the transmitting power of a glass is to be tried, it must be placed over one of the holes of the small moveable piece, which then is fastened with a button, on the opening left for it in the circular wooden screen. Then, looking through the hole of the pasteboard at the 2 vanes, and bringing that which is seen through the glass near enough to give an image equally bright with that which is seen through the open hole, the observation will be completed. Having measured the odd inches by a pair of compasses, or immediately by a scale, we deduce, as usual, the transmitting power, by taking double the logarithm of the distance of the 785 VOL. XC.] PHILOSOPHICAL TRANSACTIONS. farthest vane from the lamp, from double the logarithm of the distance of the nearest vane. The remaining logarithm is that of the transmitting power, as compared to the light coming directly to the eye from the other vane. I have now only to remark, that the use of this instrument requires some practice, especially when coloured glasses are to be examined ; it will however be found, that the dif- ference of the colour of the 2 objects, when their light is brought to an equality, may be overcome by a little abstraction, which is required for the purpose; for, by attending only to brightness, it has often happened to me, that both objects appeared at last of the same colour; which proved to be some mean between the 2 appearances considered separately. Some glasses stop so much light, that it will be adviseable to take them by the assistance of an intermediate one. Thus, instead of comparing the open vane directly to a red glass, I settle first the ratio of the violet one to that vane ; then, taking the ratio of the red to the violet, and compounding these 2 ratios, the re- sult will be more accurate. The reason for this will be easily comprehended, when the construction of the apparatus is considered. For a red glass, immediately com- pared to the open vane, would require its object to be brought extremely near the lamp, while the other must remain at a very great distance. This would occasion a considerable difference in the angles, both of incidence and of reflection, between the rays falling on one vane, and on the other. But, by dividing the observation into 2 operations, we avoid the errors that might be occasioned by the former arrangement. In the following table, the 1st column contains the names of the different substances through which light has been transmitted. The 2d column shows the transmission of light, expressed in decimal fractions ; or the proportion which it bears to the whole incident light considered as unity. An arithmetical complement to this fraction, or what it wants to unity, will therefore give us the proportion of light which is stopped by each of the substances contained in the 1st column ; and that quantity multiplied by 1000 is placed in the 3d column. table 7* Substances without colour. Transmission Bluish- white glass 914 Flint glass 966 Crown glass 797 Coach glass 832 Stoppage. Transmission. 86 Iceland crystal 850 34 Talc 910 203 Easily calcinable talc 712 168 Very dark red glass 0001335 Dark-red glass 000188 . . 999-8 Orange glass 221 .. 779 Yellow glass 681 .. 319 Pale-green glass 465 . . 535 Dark-green glass ....... .05 1 1 . . 949 Bluish-green glass 231 . . 76'9 Glasses of the prismatic colours. Transmission. Stoppage. 999-9 Transmission. Pale-blue glass 3l6 Dark-blue glass 199 Indigo glass 000281 . Pale-indigo glass 0218 Purple glass . 00675 Violet glass 0452 Stoppage. 150 90 288 Stoppage. . 684 . 801 i 9997 . 978 . 993 . 955 VOL. XVIII. 5H 786 PHILOSOPHICAL TRANSACTIONS. [anno 1800. Transmission. Empty tube and two glasses .796 Well-water and ditto 789 Sea-water 712 Liquids. Stoppage. Transmission. . 204 Spirit of wine and 2 glasses .776 , 211 Gin 374 . 288 Brandy 00381 Scattering Transmissions. Transmission. Crown glass, one side 1 . . ^ rubbed on emery. $ Coach glass, ditto 115 Crown glass, both sides ^ 0gR * rubbed on emery. J Coach glass, ditto 0542 The two first, together .. .03158 . The two next, together . . .0208 Stoppage. 854 885 932 9*6 969 979 Transmission The four first, together . . .00456 Olive colour, burnt in glass .0160 Calcined talc 00345 White paper 00556 Linen Oi83 White Persian 0841 Black muslin .263 Stoppage. . 224 . 626 • 996 Stoppage. 995 984 997 99* 952 916 737 Table of the Proportional Terrestrial Light Scattered by various Substances. The same apparatus which has been used to gain the results of the preceding table, has also been employed for the following one, with no other difference than that while the vane with the white paper remained on one side, the other vane was successively covered by the objects whose power of scattering light was to be ascer- tained, and both vanes were viewed directly through the 2 open holes in the screen ; the eye being stationed in the same place as before. It will be found, that this table contains the scattering of more objects than have been referred to in the preceding paper; but, as I made these experiments in a certain order, I thought it would be acceptable to give the table at full length. The 1 st column gives the names of the objects ; and the 2d contains the number of rays of light scattered by them, when compared to a standard of white paper, which is supposed to scatter IOOO. table 8. Rays of light. White paper scatters 1000 Message card 1 000 White linen 1008 White cotton 1054 White chamois leather, smooth side . . 1228 White worsted 620 White Persian, suspended 67 1 White Persian, on whitish-brown paper 719 White Persian, on white Persian 818 White muslin 827 Red paper 158 Deep pink-coloured paper 513 Pale pink- coloured paper 62 1 Orange paper 619 Yellow papei 824 Pale-green paper 549 Dark-green paper ; 308 Rays of light. Pale-blue paper 665 Dark-blue paper 1 49 Indigo paper, with a strong gloss .... 144 Dark-violet paper scatters 75 Brown paper ] 01 Black paper, with a strong gloss 420 Black satin. . . 102 Black muslin, suspended 64 Black muslin, upon black muslin .... 18 Black worsted 16 Black velvet . , 7 Tin-foil 8483 Iron 10014 Copper 13128 Brass 43858 Gold-leaf paper 124371 I cannot help remarking, that in making these last experiments, I found that black paper could not be distinguished from white ; and that, on bringing it a little VOL. XC.] PHILOSOPHICAL TRANSACTIONS. J87 nearer to the light than it should be to make them perfectly equal, any of my friends who happened to be present, would mistake the black for the white. XX. An Account of the Trigonometrical Survey, carried on in 1797* 1798, and 1799, by Order of Marquis Cornivallis, Master-General of the Ordnance. By Capt. Wm. Mudge, F. R. S. Communicated by the Duke of Richmond, F. R. S. p. 539. This is now one more of the reports on the national military survey of this country, which has been carried on for many years, under the immediate and suc- cessive conduct of General Roy, Colonel Williams, and Capt. (now Col.) Mudge, of the Royal Artillery, and which is still continued under the direction of the same Col. Mudge. The contents of the work now meeting the public eye, are important and numerous: it is divided into sections. The 1st contains the calculations of the sides of the principal and secondary triangles extended over the country in 1 797, 1798, and 1799; with an account of the measurement of a new base line on Sedge- moor, and a short historical narrative of each year's operation. The 2d section contains the computed latitudes and longitudes of those places, on the western coast, intersected in 1795 and 179^, ana< also such others, since determined, as lie conveniently situated to the newly- observed meridians. This section also contains the directions of those meridians ; one on Black Down, in Dorsetshire; another on Butterton Hill, in Devonshire ; and another on St. Agnes Beacon, in Cornwall. Among the contents are also to be numbered the bearings, distances, &c. of the stations and intersected objects, from the parallels and meridians. The 3d and last section contains the triangles which have been carried over Essex, the western part of Kent, and portions of the counties joining the former, Suffolk, and Hertfordshire. It is with satisfaction stated, that Mr. Gardner, the chief draftsman, with his assist- ants, had nearly completed the survey of this extensive tract, which, no doubt, like the map of Kent, will be given to the public : the materials for these different sur- veys are ample, and will be found in this section, which concludes with the altitudes of the stations and mean refractions. Before advancing farther in the work, Col. M. entertained ideas of condensing all the data in his possession, and distributing them in it ; but, when he found his paper would, in that case, be too large for the Philos. Trans, he desisted, content- ing himself with presenting little more than a moiety : it is, even now, he says, of inconvenient magnitude, but he could not with propriety still further abridge it, having in several instances rejected important matter. That he will therefore take an early opportunity of compiling a 4th account, in which will be given the latitudes and longitudes of those places, in Essex, Kent, &c. found in the last section. In the former accounts of this survey, the conductors were particularly guarded in not intermixing their contents with distances determined from numerous doubtful inter- 5h2 788 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. sections ; and experience has hitherto not detected above 3 or 4 errors arising from wrong bearings or misnomers. Previously indeed to the compilation of them, a great part of the objects in Sussex, Hampshire, and the Isle of Wight, were verified by Mr. Gardner, in process of an extensive survey, carried on by the order, and performed for the service of the Board of Ordnance. This gentleman will also have it in his power to detect any errors, if. such exist, in the names of places to the west- ward ; as the Master General has been pleased to issue his directions for the survey of Devonshire, and as much of Somersetshire and Cornwall as will square the work. The principal object proposed to be accomplished in the year 1797, was the deter- mination of the directions of meridians at proper stations, in order to afford the necessary data for computing the latitudes and longitudes of places intersected in the surveys of 1795 ana* 1796* From errors which are the result of computations made on the supposition of the earth's surface being a plane, it was expedient that new directions of meridians should be observed, when the operations are extended, in eastern or western directions, over spaces of 60 miles from fixed meridians. The distance from Dover to the Land's End being upwards of 300 miles, it becomes necessary, on this principle, that 4 directions of meridians should be observed ; which, with that of Greenwich, amounts to 6, dividing this space into 6 nearly equal parts. Whatever might be the stations farther to the westward, which offer as fit places for these observations, Dunnose in the Isle of Wight seemed highly eligible, not only because it is removed the necessary distance from the meridian of Greenwich, but also because it commands a most extensive view of the western coast : therefore, as the direction of the meridian was observed on this station in 1793, it became necessary to fix on 3 other places only. In the selection of these stations, it was wished to have found such as should lie nearly in the same parallel, each intermediate one being visible from those east and west of it; by which means, the differences of latitude between their respective parallels would be accurately de- termined. When the party was at Dunnose, in the year 1793, a hill at a very considerable distance, in a direction very nearly west, was seen just rising out of the horizon. It then occurred that this spot would, at some future period, be a very proper one for a station where a new direction of the meridian might be observed. Experience, in the survey of 1795, led to the belief that this hill was actually Black Down in Dorsetshire ; therefore it was determined that the operations should com- mence at that station, and the event verified the truth of the suppositions. As the high land in the vicinity of Teignmouth, in Devonshire, cuts off all view of the southern extremity of Dartmoor from Black Down, the necessary alternative was, the firing of lights on some remote station, communicating with Butterton. Rippin Tor was quickly discovered to be the most proper spot ; and that eminence would, in every point of view, be a most eligible one for a new direction of the meridian, if the hills in the middle of the moor were not considerably higher. It was therefore chosen only with a view of being subservient to the purpose of finding the latitude of Butterton. From Black Down, the party removed to Butterton; at VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 789 which place but few observations were made, the weather being either tempestuous or hazy, during the greatest part of the time they were at that station : these were however made under favourable circumstances, in other respects, and are there- fore likely to afford accurate results. As in the case of Rippin Tor, with respect to Black Down, so Hensbarrow, in Cornwall, was selected as the spot for con- necting St. Agnes Beacon with the station on Butterton; for these latter are not visible from each other, the high land about St. Austle, on the northern part of which is situated Hens or Hengist barrow, being higher and intermediate. The staff to which the lights and star were referred, was placed on a hill called Hem- merdon Ball, a secondary station in the series of 1795. On the 1st of May, the party proceeded to St. Agnes Beacon, at which place the observations were com- pleted on the 8th. After these directions of meridians were determined, the party proceeded with the survey, and for that purpose from St. Agnes Beacon repaired to Trevose Head, a promontory on the northern coast of Cornwall. Hence they continued the survey through Cornwall, Devon, and the other counties to the eastwards in succession ; the account of which, and the list of the angles taken at the several stations, concludes the account of the operations of the year 1797* The object first attained the next year, 1798, consisted in a trigonometrical survey of the counties adjacent to the northern and southern shores of the Thames. The stations in Kent, besides that of Wrotham, where a former survey ended, were Gravesend, Gad's Hill, and the Isle of Sheppey ; those in Essex were Hadleigh, South End, and Prittlewell. Observations made from these places afforded data for the proposed survey. The new base on Sedgemoor was next measured. This measurement was begun in July, and finished in August ; in the course of which, very little interruption arose from any inclemency of weather. It is unnecessary to enter minutely into a description of the difficulties which arose from the frequent in- tervention of ditches ; let it suffice to observe that, possessed of a 50- feet chain in addition, and similar to the 100 feet one, these were rendered less material than they would otherwise have been. King's Sedgernoor being sufficiently level, the base was measured horizontally ; an advantageous circumstance ; and the process was quite similar to that used in measuring the former bases, that have been already described. After the conclusion of this operation, the party proceeded to select such stations in the neighbourhood of the base, as might afford means of connect- ing it with the triangles carried on in the preceding year. The two chosen for this purpose, were Dundon Beacon, and a spot near the village of Moor Lynch. The station at Ash Beacon was visited subsequent to these just spoken of, and afterwards that on the Mendip Hills, for the purpose of taking the angle between Moor Lynch and Dundon Beacon. The operations of 1798 then terminated with a diligent search after some spot in Cornwall ; for a base of only 2 or 3 miles in length : this search however was fruitless. On commencing the account of the operations in 1799> *t is observed, that were the length of a degree of the meridian, in these latitudes, accurately knownj 790 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. the most eligible method of carrying on the survey would be, that of working between any two determined parallels of latitude, till the space between them was completed. Yet this mode would manifestly be subject to some slight innovations, from the necessity of measuring bases in certain stages of the work ; it would be right however to adopt the principle for general practice. Under this idea, it would have been proper to have commenced the operations of this year in Somer- setshire, and to have carried on the triangles from the neighbourhood of the new base there, into the north of Devon. It is mentioned in one of the former accounts, that a zenith sector was formerly bespoken of Mr. Ramsden, by his Grace the Duke of Richmond, for the purpose of aiding the design of measuring the length of a degree of latitude in this country. The pressure of other busi- ness caused Mr. Ramsden to lay aside this instrument, after he had considerably advanced in its construction. The real necessity however for being supplied with an instrument of this description being made known to him, he resolved to take it in hand again, and complete it. Relying on the strength of his assurances to this effect, Col. Mudge determined to relinquish the intention of proceeding to the westward ; and resolved to commence this year's operations, with running up a series of triangles along the meridian of Blenheim. But as the Master-General issued directions, at this time, to survey Essex, and parts of the adjoining coun- ties, in the same manner, and for the same purpose, as Kent had been, Col. M. was obliged to suspend, for a short time, the intention of proceeding with the measurement of a meridional degree, and to devise the best means for carrying his lordship's instructions into execution. For this purpose therefore, before any stations were chosen in Essex, the county was very minutely examined ; when it appeared that insuperable difficulties would occur, if the survey were prosecuted with the large theodolite only. The range commencing at Havering Bower, and running to Gallywide Common, cuts off a regular communication between the stations subsequently chosen in the southern and northern parts of Essex. The difficulty resulting from this circumstance was made still greater from the want of success in the endeavours to find one spot on this range, pfoper for a station. The eastern part was, in some degree, found more favourable ; but it was discovered that, even here, the small instrument must frequently be used as a substitute for the large one. Under these disadvantages, the survey commenced in March ; the large theodolite being taken to a station on Hampstead Heath. From Hampstead, the instrument and portable scaffold were carried to Langdon Hill, and thence to Triptree Heath, near Maiden ; whence the party repaired to Highbeech, leaving the remainder of the county to be sur- veyed with the small circular instrument ; which seems to have been done with considerable accuracy. After the necessary observations were made at Highbeech Col. M. proceeded to Shotover Hill, in Oxfordshire ; and before May elapsed had reconnoitred the country. As the distance between Inkpin Hill and Highclere, appeared to be shorter than was necessary for a base on which the northern VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 701 triangles were to rest it became certain, that their sides would depend on the base on Hounslow Heath. The only means by which the series now proposed to be carried westwards, for the double purpose of forwarding the survey, and also of finding a portion of the meridional arc, could be properly connected with the triangles in the neighbourhood of Salisbury Plain, was the side just spoken of; for the high land in the vicinity of Calne, intercepted the view of the stations on the Marlborough range, from White Horse Hill. In order however to make a connection, though imperfect, an immediate station was chosen on this high intercepting land. At Shotover Hill the party separated, each having its instru- ment. This article is closed with enumerating the names of the stations visited and observed, and mentioning that Shotover Hill and Cumner Hill, in Oxford- shire, were selected principally with a view of ascertaining the situations of the observatories at Oxford and Blenheim. The names of the stations were, Nuffield, White Horse Hill, and Scutchamfly, in Berkshire. Shotover Hill, Cumner Hill, Whiteham Hill, Crouch Hill, and Epwell Hill, all in Oxfordshire. Those in Gloucestershire were, Pen, Cleave, Broadway Beacon, and the Malvern Hills. The Lecky Hills, in Worcestershire. Corley and Nuneaton, in Warwickshire. Bardon Hill, Naseby Field and Barrow Hill, in Leicestershire. Arbury Hill, and Souldrop, in Northamptonshire. Quainton, Brill, Wendover, and Bow Brick- hill, in Buckinghamshire. Woburn Park, and Lidlington, in Bedfordshire. Kinsworth, Lillyhoe, Berkhamstead, Tharfield, and Bushy Heath, in Hertford- shire. From the last mentioned station, the party returned to London, in Octo- ber. A list is here added of the quantities of all the angles, at those stations, taken this year 17 99 ; which is followed by a description of the situations of all the stations, where the angles were observed ; by which they may be easily dis- covered again, on any future occasion. Next follows the account of the measurement of the base, before-mentioned, on Sedgemoor, including the remeasurement and adjustment of the chains. The result of the whole is as follows. The overplus of the 273d chain was measured by Mr. Ramsden, and found to be 23.517 feet; therefore the apparent length of the Feet. base was 27676.4S30 From the measurement in the riding-house of the Duke of Marlborough, the chain a was found to exceed 100 feet, in the temperature of 54°, 0.11425 parts of an inch; to which adding the wear by the measurement on Salisbury Plain, viz. -^-, and also half the wear by the measurement of this base, viz. — — part of an inch, 0.1191 we get ' for the excess of the chain's length above 100 feet; 12 0.1191 therefore --£- X 272.8 = 2.7075 feet; which add -f 2.7075 12 The sum of all the degrees shown by the thermometer was 985 1 1 ; 7^2 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. therefore (-^— - 54° X 272.8) X ^~ = 3.1069 feet; which Feet. also add + 3.1069 Again, from the comparison of the 50-feet chain with the standard b, it appeared that the excess above 50 feet, in the temperature of 54°, was O.O9075 parts of an inch; therefore /fej X 8 = 0.0005 part of a foot: this also add -f- 0.0005 The sum of all the degrees shown by the thermometers placed by 1372 the sides of the 50-feet chain, was 1372; therefore (—7 54° X 5 4) X : — ■" = 0.0365 parts of a foot: and this add -f 0.0365 The sum is 27682.3944 And for the reduction of the base to the temperature of 620, viz. 0 01237 x 272 8x8° for 8° on the brass scale, we have - — — \ =2.2497 feet; which subtract — 2.2497 Therefore, the length of the base is , 2768O.1447 which, neglecting decimals, may be taken at 27 680 feet. As to the probable error of the above conclusion, Col. M. knows not how to form a just opinion. On ground sufficiently hard, and otherwise favourable, he thinks a base of 5 miles might be measured so accurately, as to afford a result not differing from the truth more than 3 inches: but, on this occasion, he should not suppose the error can be less than 6, nor more than 9 inches. Next follows a calculation of the sides of certain principal triangles in Cornwall and Devonshire, not necessary to be here detailed ; and afterwards the sides of all the other angles in succession, from the west towards the eastern counties. After these particulars are stated the circumstances relating to the latitudes and longitudes of the chief stations, and the direction of the meridian at the same. After which occurs the following note : It may probably be expected, says Col. Mudge, that I should determine the directions of the meri- dians at Black Down, Butterton Hill, and St. Agnes Beacon, by calculation, and afterwards compare them with the observed ones 5 I have desisted from the measure in the body of the work, and reserved the little I have to say for this note. If the earth were a perfect sphere, or an ellipsoid of known dia- meters, the direction of the meridian, at any station not very remotely situated from the parallel of an- other, might be determined, provided the direction of the meridian at that station were observed, and the value of the arc subtended by the space between them pretty accurately ascertained, and also the latitude of the station, at which the angle is given, nearly obtained. Thus, if it be required to find the angle at Dunnose, between Beachy Head and the meridian, from the observed angle at the latter station, and the arc between them, we shall have 39° 15'36".3, the co-latitude of Beachy Head, and 55' 28". 7 for the oblique arc. These data, two sides and an included angle, give 1° 26v 48".4, for the difference of longitude between Beachy Head and Dunnose, and 81° 56' 52''. .6, for the angle which the meridian at the latter makes with the former station. The difference of longitude found in a rather more correct way, has been heretofore shown to be 1° Q6' 47 ".93, and the angle at Dunnose was also shown to be VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 7g3 81° 56' 53", from observation, which may be considered the same with that found by this mode of com- putation. In all cases in which the data were equally correct, no doubt the direction of meridians might be computed, without fear of the results deviating much from the truth ; but if it be required to find the angle at Black Down, from the observed direction of the meridian at Dunnose, a different method must be used. It is however less accurate than the former one, and it has been expressly for this reason, that I have not introduced this subject into the account. In the adjoining diagram, suppose b to be Black Down; D, Dunnose, and n, Nine Barrow Down; also let pb, the meridian of Black Down, be pro- longed to m, and dm be drawn, fm being = pd. Then we shall have 3 spherical triangles, bpd, bnd, bmd. Now the angle nbd was found from observations to be 4° 30' 28", and bnd 172° 27' 33". 5; these give the angle bdn = 3° 1' 59". 5, nearly, because the excess of the 3 angles above 180° is 1". The observed angle at d, Dunnose, between Nine Barrow Down and the meridian dp, or pdn, was 87° 56' 53"; therefore 87° 56' 53" — 3° 1' 59".5 = 84° 54' 53".5, is the angle at d, between the meridian and N * the station on Black Down. Now, the difference of longitude between b and n, or the angle at p, has been already found = 1* 20' 46".4; and since bp is very nearly = pd, and pd is small, we shall have rad. : tang. |r : cosine dp : cosine bmd = 89° 28' 47". But the angle pdb has been found = 84° 54' 53". 5; therefore 89° 28' 47" - 84° 54' 53".5 = 4° 33' 53".5, the angle bdm; hence 180° Dundon and Lugshorn Corner ' Moor Lynch and Greylock's Foss-way 4. Lugshorn Corner and Greylock's Foss-way . . Cadon Barrow and horizon of the sea in the direction of Trevose Head Ditto in a northern direction Brill and Nuffield '.'"'* Broadway and Stow Epwell and Broadway Highclere and White Horse Hill JL Nuffield and White Horse Hill {jI Nuffield and Bagshot ^l Epwell and Stow j Brill and Stow on the Wold Wendover and Bow Brickhill Kinsworth and Bow Brickhill Shotover and White Horse Hill Epwell and Brill Bow Brickhill and Brill 0 T TV tV T7 _i TV 1 The height of the station on Trevose Head, above the surface of the sea at low-water, was determined in 1797, by levelling. The transit instrument was used for the purpose ; and there is reason to believe the result, 274^- feet, is within a very few inches of the truth. In the Philos. Trans, for 1797, the height of the station on Maker Heights is said to be 402 feet ; this was also found by levelling. The altitude of St. Agnes Beacon, determined from that station, is 5QQ feet ; but if the calculation be made from the base of altitude at Trevose Head, the height of that station, above the level of the sea, will be 62 1 feet, which gives a difference of 22 feet. It must be recollected however, that in the first result, the computation was carried through 2 intermediate stations, which gave 3 arcs, and as many mean refractions ; and, considering the extreme variableness to which refractions are liable, we are assuredly not to consider 22 feet deviation from the truth as a large quantity. Besides St. Agnes Beacon, the altitudes of Cadon Barrow, Brown Willy, Hens- VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 795 barrow, and Bodmin Down, have been determined from that of Trevose Head. Of the remaining stations, some are derived from Maker Heights, others from Dunnose : most of them are mean results, that is, each station has generally been found 2 ways ; and as it will serve to show what errors proceed from irregularity of refraction, and imperfection of observation, I shall exhibit a few particulars. Height of Deduced from Feet. Mean. ( Maker Heights 1 169 Black Down < 1 16*0 t Carraton Hill 1 152 C Black Down 609 St. Stephen's Down X 6*05 LCarraton Hill 600 C Bradley Knoll 779 Westbury Down < 775 ( Beacon Hill 771 {Mendip Hills -. . 703 700 Westbury Down 6*96" C Mendip Hills 335 Moor Lynch 2 330 I Ash Beacon 325 rDundon Beacon 46* Lugshorn Corner 1 49 LGreylock's Foss-way 52 {Highclere 1014 1011 Beacon Hill 1009 r Bull Barrow 653 Ash Beacon 1 655 (.Bradley Knoll 657 The above will sufficiently show what dependence is to be placed on the heights deduced from observed angles of elevation or depression ; the results are indeed often less consistent, and frequently unsatisfactory ; but generally they run on a parallel with these. The data from which all the heights have been computed, accompany the article. The measurement of the base on Sedgemoor, showed a fall of about 7 feet from Lugshorn Corner to Greylock's Foss-way : therefore, supposing that fall to be gradual and constant, all the way from the latter station to the surface of the sea at Bridgewater Bay, we shall get 24 feet, for the height of Lugshorn Corner from the surface of the sea. The altitude of this station, deduced from that of Trevose Head, is 49 feet ; and subtracting 3 feet from it, the height of the bank on which the instrument stood above the moor, we get 4() feet for the height of the moor at Lugshorn Corner, above the level of the sea at Bridgewater Bay. But this height, supposing the fall regular, is proved to be 24 feet. There is therefore a difference of 22 feet, granting the whole of this to be an error on the side of the survey ; but as the general surface of the moor at Bridgewater Bay is several feet above the surface of the sea, we may take a moiety of 24 feet, for the error of the computed height of the station at Lugshorn Corner. The refractions contained in this account, like those in the former papers, tend to prove, that when rays of light pass horizontally, and considerably distant from 5 1 2 7Q6 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. the surface of the earth, they are less bent or refracted from their rectilinear courses, than theory and opinion have laid down as fact. It is very certain how- ever, that objection lies against particular conclusions drawn from such data as we possess ; because the angles of elevation and depression of corresponding stations are observed at different times, and almost always therefore under different cir- cumstances ; but with the experience and continual practice of thus obtaining means of computing these refractions, though we may not be able to determine the re- fracting power of the air under given circumstances, yet, as the causes which render it variable, are as likely to predominate when the angles of depression or elevation are observed from low stations as when observed from high ones, we may be enabled to make some general deductions*. When the instrument formerly made use of by General Roy was entrusted to my care, I possessed the means of determining, in a more accurate manner than had yet been done, the refractive power of the air near the horizon. To devote much time to it, has not, as yet, been in my power ; because a more rapid exten- sion of the survey was an object of greater importance. I did not, however, lose any opportunity which the subsequent season offered; the 1st was, when the in- struments were at White Horse Hill and Whiteham Hill ; the 2d, when one was stationed at Brill and the other at Arbury Hill; and the 3d opportunity offered it- self, when one party was stationed at the latter place and the other at Wendover. On these occasions, the instructions by which I governed myself were to observe the elevation or depression of the corresponding station at the expiration of every hour, beginning at 6 a.m. and to have the watch well regulated from observed al- titudes of the sun's limb. I was also very minute in having entered in the book the state of the weather ; to keep the instrument properly sheltered from the wind ; * As many instances of strong atmospherical refraction have been related, and ingeniously accounted for, in some of the late publications of the r. s., I think, it right to mention, by way of note, a very extraordinary instance of its variability. In the month of June, 1795, when the instrument and party were stationed at Pilsden Hill, in Dorsetshire, on a particular day, at about the hour of 4, I em- ployed myself in observing the angles of depression or elevation of the surrounding hills. After I had done all that was necessary in this matter, I turned the telescope to Glastonbury Tor, and observed its depression. The air was so unusually clear, that, desirous of proving to a gentleman then with me in the observatory tent, the excellence of the telescope, I desired him to apply his eye to it : he did so, and agreeably to a desire he expressed, I again took the depression of the upper part of the old building, which I was enabled to do with great accuracy, and found it 2" different, the first being 3(y.O" and the last 30'.2". The unusual distinctness of this object led me to keep my eye a long time at the te- lescope; and while my attention was engaged, 1 perceived the top of the building gradually rise above the micrometer wire, and so continue to do, till it was elevated 10'45" above its first apparent situa- tion ; it then remained stationary, and as night drew on, the object became indistinct. The following evening, I observed the depression again, and found it 2O/.50". To what cause this extraordinary change in the refraction could be owing, I am at a loss to conjecture. The former part of the day had been warm, with little wind, and cloudy. The thermometer, at the time of observation, was 65°, and continued stationary for a considerable time. The sky was cloudy, but yet, as before ob- served, the air was remarkably clear. The top of Glastonbury Tor, I suppose, is about 200 feet from the surface of Sedgemoor, over a considerable tract of which the line joining Pilsden with that object passes. The gentleman of whom I speak, as being with me in the tent, was Captain Darcy, of the Royal Engineers, who no doubt well remembers the circumstance. — Orig. VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 797 to be always cautious to adjust the level ; and also to insert the state of the air, as to temperature and density, by noting the thermometer and barometer. The height of the transit telescope above the ground was always 5± feet ; there- fore, an allowance must be made, at each station, for the angle which that space subtends at its corresponding one ; this premised, the refraction will be found from one of the two following rules, viz. if a be the contained arc, and d, d, the ob- served depressions, the quantity answering to the refraction r, will be expressed by -D-d or, if one of the angles should be an elevation, e, then r = a + e — d these rules give the refractions in the following table. 1. Arc. 2. Arc 3. Arc. 4 . Arc. White Horse Hill and Brill and Arbury Hill. Arbury Hill and Broadway Beacon and Whiteham Hill. Wendover. Epwell. i Refraction. Rf fraction. Refraction Refraction. Hour.. ptf. cont. arc. Baroro. Therm. o Hours. pts. I'Ollt. 11- 1 nun. rherm. IUurs. pt«. cont. arc. Barom. Therm. Hours. pis. i out. liaroin. Therm. ir.pt.. in. pts. „ in. pts. o in. ptf. o 3 P.M. 1 io"B~ 29.5 58.0 9 a.m. 1 T5 7 29.1 63.2 5 1 1 O 8 28.8 5+.b 2 1 "3T-T 29-2 54-.1 4 ?-"4 29-5 61.0 10 TV* 29-2 68.7 6 tt't 28.8 61.5 3 TT.V 58.2 5 1 29-5 58.1 11 i Toy 29-2 68.1 4 29.1 57.5 6 T5-T 29-5 57.0 12 To-T 29.2 67.6 7 TffV 29-5 57.0 3 .M. TOT 29-2 72.5 8 l 29 6' 55.6 4 1__ T-T 29-2, 72.0 9 TT-V 29-6 54.5 9 l 7-8 29-2, 6*2.3 10 TT.'S' 29-5 54.3 1 On examining the refractions obtained on the first arc, we perceive them to have been tolerably regular from 3 o'clock till 8 ; the mean being -j-l T part of the con- tained arc. The height of Whiteham Hill is 576 feet, and that of White Horse Hill 893 feet, above the level of the sea : the ray passes therefore through a tract of air considerably elevated, as the country between the stations is, for the most part, flat and low. The air is not often clear enough, or sufficiently free from tremulous motion, for these delicate observations. On the present occasion however, the state of it was highly fit for the purpose ; and as care was taken, I am of opinion an error of more than 3", taking that of the arch of altitude into the account, cannot have obtained in any of the angles. The refractions at 9 and 10 o'clock are less than at the preceding hours ; but this does not appear to have been owing to any change in the refractive power of the air throughout the whole ex- tent of the ray, because the depression of Whiteham Hill, from the other station, varied little at those hours. These changes in the observed angles of elevation at Whiteham, 44" and 42" being the differences, without corresponding ones at White Horse Hill, prove that some partial alteration, from floating strata, had taken place in the refraction near the former station. It will be perceived that a case may be constructed in which this will take place, causing a great variation in one of the angles, while the other apparently remains the same : and this suggested the idea, that to afford any accurate conclusions in this way, a long series of obser- vations would be necessary. It further appears that dew could not have caused these differences at Whiteham Hill, since the same cause would equally operate to vary he observed angles at White Horse Hill ; but these remained nearly the same. 798 PHILOSOPHICAL TRANSACTIONS. [anno 1800. The refractions on the 2d and 3d arcs, I consider as most accurate, on account of the great distance between the stations ; and also as more to be depended on, from the circumstance of the ray generally passing 300 feet above the ground. The 4th arc affords another instance of the refraction varying at one station, and remaining constant at the other. This was owing to the intervention of some par- tial stratum of air, nearer to Epwell than Broadway Beacon. The refractions, de- duced from these contemporary observations are inconclusive. The mean refractions, neglecting the 4th arc, brought under one point of view, will be as follows. Arcs. Mean height of ray above the sea. Feet. 734 774 854 Refraction. Propl. pt. Barom. Therm. in. pts. 29.5 2().2 28.8 57.8 67.8 58.1 ] t White Horse Hill and Whiteham bury Hill and Bril, 5 first refracs. - 3. Arbury Hill and Wendover - If the air had been in a quiescent state, previous to and also at the times when these observations were made, it might be expected that the differences of altitudes in the stations would be obtained, tolerably near the truth, barometrically. The remarks in the tables appertaining to the 1st and 2d arcs, shew that such opportu- nities offered ; but those which belong to the 3d, prove the wind to have been fresh ; and, as the space between the stations which constitute the extremities of that arc is 34 miles, nearly, it is not to be expected that a true result should be obtained. The differences of altitudes of the stations constituting the extremities of the first 2 arcs, obtained by means of the observed angles of elevation and de- pression, as well as from the heights of the mercury in the barometer, will be, Arcs. Obs. Ang. Barom. Diff. 1 3J7 282 35 2 60 15 45 The little that has been done on this subject, points out the necessity of doing more ; it therefore remains to observe, that I shall lose no opportunity of employ- ing the apparatus committed to my charge in the best and most diligent manner, both as relating to matters of refraction, and to all others connected with the Trigonometrical Survey. ^_ Note referred to at page 746 of this Volume. It was intended to subjoin to Mr. Volta's description of his electrical pile or battery, an account of Mr. Davy's discoveries, which constitute a new aera in chemistry, relative to the decomposition of the alkalies and their metallization, by means of the above-mentioned apparatus. But on further reflection it appeared, that even a summary statement of those brilliant discoveries would far exceed the limits of a note, and indeed was scarcely necessary, from the circumstance of Mr. Davy's experiments having been so lately communicated to the public, in the Philos. Trans, (see Bakerian lecture, 1808) which, from the commencement of the present century, where our labours terminate, are, or will be, it ii presumed, in the possession of the Subscribers to this Abridgment. END OF VOL. XC OF THE ORIGINAL, AND OF THIS ABRIDGMENT. INDEX. INDEX TO THE PHILOSOPHICAL TRANSACTIONS ABRIDGED. N, B. The Roman numerals denote the volume, and the Arabic figures the page. ACI jf\jBBS, Rev. Cooper, failure of haddocks on the north coast, xvii. 243 Abdomen, case of tumours of, vii. 277, Rutty — injecting of liquors at tapping, ix. 8, Hales — a steatomatous tumour in, xiii. 108, Henley — see Tapping, Dropsy, Hydatids. Abernethy, John, cases of uncommon formation in the vis- cera, xvii. 295 — some particulars in the anatomy of the whale, xvii. 6'73 — observ. on the foramina Thebesii of the heart, xviii. 287 Aberrations, in object glasses, remarks on Mr. Euler's theorem, x. 401, Short x. 402, Dollond x. 403* 404 Euler — see Light, (Optics) . Abruzzo, journey into the province of, xvi.181,. . Hamilton Absorbents, ill effect of earthy, on the kidneys, viii. 452, Breyne Absorption of moisture from the atmosphere, the relative quantity by various substances, xvi. 260, . . . Rumford Academia Naturae Curiosorum, Institution of, i. 56*1 Academy of Sciences, see Paris. Acmella, efficacy in the cure of stone, iv. 548, .... Hotton Achard, Mr., of swallows in the cliffs of the Rhine, xi. 705 Acid, of ants, experts, on, i. 554, Hulse and Fisher; experts. of Neumann and others. Note, ibid. — from other insects, i. 557, Lister — quantity of acid salts in acid spirits, iv. 483,. . Homberg — varieties in vegetable acids, xii. 479, Monro — of a new animal acid, xiv. 67 1, xv. 168, Crell — specific gravities and attractive powers of various saline bodies, xv. 3, 236, 327, Kirwan . — solution of metals in the mineral acids, xv. 327, . . Same — affinity of mineral acids to metals, xv. 336, Same — phosphor, acid procured from urine, xv. 411, DeChaulnes — a test liquor for acids, xv. 605, ... Watt — freezing of nitrous acids, xvi. 98, 425, Cavendish vitriolic acid, xvi. 105, 429, Same I xvi. 271, Keir — conversion of phlogisticated and dephlogisticated airs into nitrous acid by the electric spark, xvi. 451, Cavendish — experts, on the vapour of acids transmitted through hot tubes, xvi. 6()2, Priestley — production of nitrous acid, xvi. 606, Milner — experts, on molybdic acid, xviii. 21, Hatchett — decomposition of the acid of borax, xyiii. 457, .... Crell — quantity of gallic acid in various barks, xviii. 527, Biggin — experts, for decomposing the muriatic acid, xviii. 641, Henry Acidity, on the principle of, xvi. 419, 473, 518, . . Priestley Acipenser huso (isinglass-sturgeon) account of, ix. 335, Collin son AIR Acoustics, on the doctrine of, ill, 5, Bishop of Ferng — experts, and observations on sound, iv. 338 — see Sound, Music, &c. Acres, on the number of in England, v. 620 Actinia description of different sorts of, xi. 525, ..Gaertner — nature of the actinia sociata, xii. 46*8, Ellis — see Mnemonics (Sea). Adams, Arch., m. d., a monstrous calf; remarks on the human ear. v. 365 — case of an apoplexy, in which the nerves were affeeted on the side of the brain unobstructed, v. 397 — manner of making microscopes, v. 551 Adee, Swithin,M.D. agitation of the waters at Cobham, x.649 Adits, see Mines. Adriatic sea, on a natural history of. x. 706 Donatt Aerostation, see Air-balloon. Aery, T., m. d., cure of a wound of the cornea and uvea, ix. 535 iEtna, chronological account of the eruptions of, i. 357 — particulars of the eruptions in 1669, i. 384; of the mi- neral substances thrown out, 389 — height of, and eruption of 1669, i. 637, Borelli — eruption of 1755, x. 608, Magistrates of Mascali 1766, xii. 419, Hamilton — journey to, and examination of, xiii. 1, Same — a remarkable rain which fell on it, xv. l65, .... Giocni ./Ether, see Ether. Affleck, Capt. agitation of the sea at Antigua, Nov. 1755, xi. 9 Africa, calculations of its geography deduced from observs. of the rate of travelling by camels, xvii. 38, . . Rennell Agaric, of oak, experts, after amputations, x. 478, . . Sharp in stopping haemorrhages, x. 479> 546, Warren - after important operations, x. 480, Same Agaric, inquiry into the species of, x. 546, Watson — successful application of, x. 621, Thornhill — (the French) the species of plant, x, 563, .... Watson — see Styptic. Aglionby, Wm., nature and qualities of silk, iv. 380 Agnus Scythicus, account of, vii, 103, Breyns Agra, method of making salt-petre at, i. 38 Agriculture, inquiries for promoting, i. 32, . . Royal Society — several plants fit for hay, iv. 136, Lister — of China, some particulars of, iv. 69-5, . . . Cunningham — see Manure. Agues, efficacy of willow bark in, xii. 1, Stone Aikin, Rev. John, bills of mortality of Warrington, 1750 to 1773, xiii. 567 Air, experts, of withdrawing it from shining wood and fish, i. 211, Boyle — on the spring and weight of, i. 303, Same — on the quantity of air in water, i. 479> Same AIR. INDEX. AIR. Air, pressure of air unfit for respiration, i. 501, .... Boyle — of its use in elevating the steam of bodies, i, 503, . . Same — on its rarity and density, i. 552, Same — - experts, on its compression by water, i. 606, 622, R. S. — effect of a varying atmosphere on bodies in water, ii. 42, Boyle on the compression of, ii. 128, Leuwenhoek — experiments for the generating of new air, ii. 239, 257, Huygens, &c. early experts, for generating air, ii. 240, note, Boyle, Wren, &c. on mixing and fermenting liquors in vacuo, 246; obser- vations thereon, 270, Boyle of its relative weight with water, ii. 478, and Note augmentation of the weight of oil of vitriol on exposure to air, iii. 1 1 — of its resistance to a projected body, iii. 265, Note on ascertaining its rarefaction by the barometer, iii. 300 Halley its velocity in rushing into a vacuum, iii. 334, . . Papin — its resistance to bodies in motion, iii. 350; Wallis cor- rection of an error in this paper, 350, 356, Notes of its effect on the colour of transparent liquor, iii. 581. Slare experiments on its refraction, iv. 432, Lowthorp quality of the air produced by gunpowder fired in vacuo, v, 1 83, Hauksbee propagation of sound in condensed air, v. 202, .... Same diminution of sound in rarefied air, v. 203, Same resilition of bodies in common and condensed air, v. 208, Same — its proportionate weight to water, v. 288, Same — effect of its compression against two hemispheres, v. 356, Same quantity produced from fired gunpowder, v. 363, Same — effect of a violent impulse on, v. 364, Same different densities at different temperatures, v. 41 6, Same exper. of condensing several atmosph. of air, v. 45 1, Same — exper. on the fall of bodies in common air, v. 669, Same means of supplying divers with air, vi. 258, 521, Halley — resistance of air to falling bodies, vi. 428, 430, Desaguliers — effect of its refraction on astronom. observ. vi. 517, Halley — machine for ventilating rooms, viii. 12, 13, 15, Desaguliers — on the inflammability of air in a mine, viii. 77, . . Maud on the nitrous particles which abound in, viii. 296, Clayton — on the electricity of, x. 434, . . ... Mazeas — antiseptic effects of ventilation, x. 635, 641, 642, Hales — physical and meteorological observ. xii. 223, . . Franklin — quantity of fixed air in alkalis, xii. 229, .... Cavendish — effects of effluvia on the air, xiv. 322, White — salubrity of air at different places, xiv. 56*8, . . Fontana sea air, xiv. 692, Ingenhousz — a new eudiometer, and experiments with it, xv. 35 1, Cavendish — experts, on the resistance of, xv. 362, Edgworth — on its conducting powers with regard to heat, xvi. 109, Rurnford — experts, on the mechan. expansion of, xvi. 372, Darwin — observ. on the air of respiration, xvi. 647, .... Priestley — an unusual horizontal refraction of the air, xviii. 436, Vince — quantity discharged through an aperture, xviii. 604, Young — direction and velocity of a stream of, xviii. 605, Same — see Aii -pump, Vacuum. — see Atmosphere, Meteors, Electricity, Damps. Airs, (Chemistry) experts, on inflam. air, xii. 299, Cavendish — experiments on fixed air, xii. 307, Same — quantity of fixed air in alkalis, xii. 311,....,... Same Airs, of the air produced by fermentation and putrefaction, xii- 316, Same — solubility of iron by fixed air, xii. 633, Lane — impregnating of water with fixed air, xiii. 587, . . Nooth — mixture of nitrous and common air, xiv. 38, Ingenhousz — effects of inflammable air on animals, xiv. 526, Fontana — a new kind of inflammable air, xiv. 547, . . Ingenhousz — nature of the air extracted from different waters, xiv. ^63, Fontana — specific gravity of fixed air, xv. 19, Kirwan — quantity of phlogiston in nitrous air, xv. 254, . . Same fixed air, xv. 255, .... Same vitriolic air, xv. 260, . . Same marine acid air, xv. 262, Same — experts, on air phlogisticated and dephlogisticated, xv. 481, 510, xvi. 15, Cavendish xv. 502, 514, Kirwan — of the component parts of dephlogisticated air, xv. 555, 569, Watt — experiments on hepatic air, xvi. 68, Kirwan — production of dephlogisticated air from waters, xvi. 198, Rurnford — experiments on hepatic air, xvi. 286, Hassenfratz — conversion of airs into nitrous acid by electricity, xvi. 451 , Cavendish — affinities of phlogisticated and light inflammable airs, xvi. 493 Austin — - on the production of nitrous air, xvi. 606, Milner — analysis of the heavy inflammable air, xvi. 632, Austin — formation of fixed air from nitrous ammoniac, xvi. 637, Same — observ. on the air of respiration, xvi. 647, . . Priestley — of the air extricated from animal substances by distilla- tion and putrefaction, xvi. 715, Same — experts, on sulphureous hepatic air, xvi. 726, .... Same — decomposition of fixed air, xvii. 50, Tennant — decomposition of dephlogisticated and inflammable air, xvii. 55 Priestley — decomposition of fixed air, xvii. 221, Pearson — see Gas Air-pump, improv. in the air-pump, x. 247, .... Smeaton — Smeaton's air-pump recommended, xiii. 504,. ; Priestley — experts, with Smeaton's, and other air-pumps, xiv. 220, Nairne — am improved air-pump, xv. 453, Cavallo Air-pump (experiments with) proposals for experiments on plants, &c. i. 150, Beale — pneumatical experiments i. 473 ; on ducks, ibid ; on vipers, 474; frogs, 475; a kitten, 477; quantity of air in water, 479 5 on shell fish, 482 ; on scale fish, 483 ; on animals with wounds in the abdomen, 485 ; on the heart of a cold animal, ibid, Boyle — comparison of the time necessary to kill an animal by drowning, and by withdrawing the air, i. 486, . . Same — of animals in air greatly rarefied, i. 490, Same — effects of the same air when rarefied, and when con- densed, i. 494, Same — experiments of the production or growth of animals in the exhausted receiver, i. 495, Same — expansion of blood and milk in the receiver, i. 498, Same — air latent in the soft parts of the body, i. 499, • • Same — power of assuefaction to enable animals to live in air extremely rarefied, ibid, Same — pressure of air unfit for respiration, i. 501, Same — continuance of a slow-worm and leech in, i. 505, Same — experts, on creeping insects, i. 506 j on winged insects, 507, Same — necessity of air to ants, mites, &c. i. 510 ALM INDEX. AMY Air-pump, experiments on various animals, ii. 271, Huygens and Papin — various experiments with, ii. 272, Same 4- an experiment with, ii. 488, Sturm — effect of the pressure of atmospheric air on two hemi- spheres in the receiver, v. 356, , Hauksbee — see Vacuum. Air-balloon, on giving a direction to, xv. 625 Galvez Akenside, Mark, m. d., biograph. account of. xi. 145. . Note — origin and use of the lymphatics, xi. 145 — effects of a blow on the heart, xii. 39 Albatross, description of the, xiv. 4, Clayton Alcanna, manufacture and use of, iv. 304 Alchorne, Stanesby, chemical examination of ores, xiv. 585 — experiments of mixing gold with tin, xv. 622 Alcyonium, description of, x. 670, Schlosser — remarks on the same specimen, x. 671, Ellis Aldebaran, occulted by the moon, 1681, ii. 510, Hevelius 1736, viii. 137, ..Bevis 1738, viii. 358, . . Kirch 1738, viii. 470, Graham Aldrovandus, Ulysses, biographical account of, 442, Note Ale, method of preserving at sea, i. 174 Aleppo, journey thence to Palmyra, iv. 33, Halifax — Account of the plague at, 1758, &c. xi. 687. . Dawes Alexander, J. place for ascertaining the earth's figure, viii, 419 — medicinal effects of Camphor, xii. 386 Alexandrinus Diophantus, biographical notice of, i. 605 Algae, of the alga marina latifolia, xi. 241, . . . . Peyssonel — on the fructification of submersed algae, xviii. 68 Correa de Serra Algebra, usefulness of, ii. 307, Prestel — - some improvements in, iii. 38, Collins — excellence of the modern, iii. 593, Halley — algebraic and geometrical problems, xii. 19, . . Waring — on finding the values of algebraic quantities, xvi. 191 Same — algebraic demonstration of Newton's binomial theorem, xviii. 33, Sewell t— see Equations, SfC. Alhazen, solu- of his prob., ii. 97, 107, Huygens and Sluse Aliment, see Food. Alimentary canal, uncommon formation of the, xvii. 298, Abernethy Alkalis, of the quantity of fixed air in, xii. 299, Cavendish — chemical analysis of mineral alkali, xv. 241, . . Kirwan volatile alkali, xv. 242, .... Same — a test liquor for, xv. 605, , Watt — formation of volatile alkali, xvi. 493, Austin Alkalizate of vegetables, remarks on, ii. 124, 158,166, Coxe Allantois, discovery of the human, iv. 577, Hale Alleman, Didier, L', description of a celestial globe, ii. 405 Allemand, M. experiments on unannealed glass, ix. l6l — agitation of the waters in Holland, 1755, x. 655 — earthquake in Flanders, 1755, x. 687 Holland, 1756, x. 696 Allen, Benj., generation of eels, iv. 199 4 — account of the gall-bee, iv. 319 — description of the death-watch, ibid. Allen Thos., m. r>., description of an hermaphrodite, i. 223 Alligator, description of those at Jamaica, i. 295, Norwood — - fossil bones of, near Whitby, xi. 259, Chapman — xi. 289, Wooller Almanack, specimen of a perpetual, ii. 495, Wood — derivation of the word al-mon-ac, ibid, note — account of 3 Hindoo almanacks, xvii. 250, , .Wilkins Almon, Rev. Edm., account of a gigantic child, ix. 95 Aloe, American, observations on the, i. 161, .... Merret — of the sap tubes in the leaves of, v. 157, • • Leuwenhoek Alston, Chas. m. d., biographical notice of, x. 204, Note — experiments on lime-water, ibid — experiments on quicklime, x. 204 Alum, efflorescence of crude alum, ii. 179» Lister — of the English alum works, ii. 458, Colwall — analysis of, ibid, note — method of making it in Naples, iv. 508, .... Silvestre — see Salfs (chemistry) Alphabet, essay for an universal, iii. 310, Lodwick — the Palmyrene, x. 522, Swinton Alpine mouse, see Marmot, Alprunus, experiments on the pus of the plague, ii. 491 — preservative from the pestilence, ii. 492 Alsace, of a remarkable oily spring at, i. 49 Altar, of a Roman altar dug up at Chester, iv. 110, Halley — of two Roman altars, iv. 198, Thoresby — a Roman altar and inscription, x. 3l6, Ward — see Inscriptions. Alternations, and combinations, doctrine of, v. 209, Thornycroft Altitude, see Heights, Barometer. Altitudes, on finding time by, xiii. 735, Aubert — see Instruments (mathematical.) Amand, (St.) on the mineral waters of, iv. 336, Geoffroy Ambe of Hippocrates, for luxations, improved, viii. 659> Le Cat Amber, answer to a query respecting it, i. 126 . . Hevelius, — , ibid Scheffer — a specimen of soft amber, i. 515, Hevelius — a piece of white, in an inland lake, i. 722, .... Kirkby — on the nature and origin of, iv. 347, Hartman — phosphoric quality of, v. 408, Wall — of a leaf lodged in a piece of, vii. 160, Breyne — on the nature of, viii. 631, Beurer — on the origin of, ix. 9, Fothergill Ambergris, nature and origin of, ii. 94, Boyle ; Note ibid — thrown on shore at Jamaica, iv. 205, Tredway — of a piece 182 pounds weight, iv. 500, .... Chevalier — found in whales, vii. 57, Boylston — from the spermaceti whale, vii. 78, Dudley — nature and properties of, vii. 66l, Neuman — experiments on, vii. 668, .... Browne and Hanckewitz — an account of, xv. 389, Schwediawer — on the production of, xvii. 6, Fawkener Ames, Joseph, case of the plica polonica, ix 356 America, distance of Asia from, ix. 341, Dobbs — of the languages, manners, &c. of the Indians of North America, xiii. 406 , Johnson American Indians, see Indians Amianthus, of a sort found in Italy, of which may be made incombustible paper, or candle-wicks, i. 599 — see Asbestos Amlwch, of the vitriolic waters at, xi. 429. Rutty Ammonitae, description of a curious fossil, ix. 632, Baker Amnii liquor, the faetus in part nourished by, x. 619, Fleming Amomum, or Tugus, description of the, iv. 347, • • Camelli Amphibious animals, on animals commonly called amphi- bious, xii. 324, Parsons, — on Linnaeus's class of amphibia, xvi. 521, Gray — see Alligator, Crocodile, Chamcelion, Ejt, Frog, Lizard, Salamander, Tortoise — see also Sea animals Amyand, Claudius, of an idiot who swallowed iron, v. 433 — child born with the bowels hanging out, vii. 52y — case of suppressed urine in a woman, vii. 529 A 2 AND INDEX. ANT Amyand, the viscus divided by a stricture, vii. 529 .11 the foramen ovale found open, viii. 54 . an inguinal rupture, with a pin in the appendix caeci, viii. 89 — remarks on wounded intestines, viii. 92 — obstruction of the biliary ducts, and imposthumation of the gall-bladder, viii. 228 — account of a bubonocele, viii. 236 — fracture of the os humeri by the muscular powers, ix. 710 — account of an iliac passion, ix. 124 — observations on the spina ventosa, ix. 245 Anastomosis, of the spermatic vessels in a woman, vii. 420, Mortimer Anatomy, (human) anatomical observations, i. 435, Grandi — professors of morbid anatomy, ii. 164, Note — anatomical observ. on the hair, teetb, bones, &c. ii. 591. Tyson — anatomical observ. with Ray's remarks, v. 310, Marchetti — some anatomical observations, vi. 76, Cheselden — glasses for preserving anatomical preparations, ix. 6l8, Le Cat method of Mr. Carlisle, ix. 6l9 — see Dissection (of human bodies) »— see particular parts of the body, also Skeletons, Monsters Anatomy (comparative) of the cbamcelion, i. 369 — — — beaver, i. 371 _ ■ dromedary, i. 372 ■■ — bear, ibid . — — — — gazelle, i. 373 ■ sea fox [squalus vulpes] ii. 290 lynx, otter, civet-cat, ii. 291 « ■ elk, coati mundi, ii. 292 ■ lumbricus latus [taenia solium] ii. 591. ..Tyson i teres [ascaris lumbricoides] ii. 605, Same — musk hog, ii. 668 Same — of glands in the stomach of a jack, iii. 71 . i the sea-calf, Barbary cow, cormorant, chamois, por- cupine, monkey, Canadian stag, Sardinian hind, pin- tado, eagle, Indian cock, bustard, demoiselle, ostrich, cassowary, and tortoise, iii. 391, 392, 393 — observations on the heads of fowls, iii. 531, ..Moulen — interior structure of fish, iv. 138, Preston — of the leech, iv. 209, Poupart opossum, iv. 248, Tyson — head of a land-tortoise, v. 598, Bussiere — of the woodpecker, vi. 264, Waller ————— siren lacertina, xii. 360, Hunter torpedo [Raia] xiii. 478 Same — see Dissection of Animals Anatomy of vegetables, see Vegetables Ancients, of the stylus and paper used by the, vii. 495, Clerk — on their knowledge of the E. Indies, xii. 408, Caverhill Anderida, situation of the city of, vi. 351 Tabor Anderson, Alex., a bituminous plain at Trinidad, xvi. 531 Anderson, James, description of Morne Garou, and vol- cano, xv. 635, Anderson, Robert, biographical account of, i. 281, . . Note Anderson, Win,, of poisonous fish in the S. Sea, xiv. 108 — of a large stone near Cape Town, xiv. 303 Andrachne, see Arbutus. Andre, (St.) Mr., extraordinary effect of colic, vi. 288 Andre, Wm., microscopic observations on the eye of the monoculus polyphemus, xv. 322 — on the teeth of the sea wolf, and chaetodon nigricans, xv. 540 — renovation of the teeth of cartilaginous fishes, xv. 542 Anemonies, (Sea) [Actiniae] on the different species of xiii. 46l, 633, xiv. 129, Dicquemare Anemoscope, description of the, ix. 36, Pickering Aneurism, of the arteria aorta, iv. 526, . . . Lafage — aorta dissected, vii. 229, Dod — nature and cause of aneurisms, vii. 231 Nicholls — containing blood without pulsation, viii. 621,Schlichting Angelis, S. de, controversy with Riccioli on the earth's motion, i. 254 Angle, on the section of an angle, vi. 6l7, .... Demoivre — instrument for taking angles, vii. 4S6} experiments made with it, 557, Hadley — contrivance for measuring, x. 364, 46*2, Dollond — on the mensuration of angles, xv. 133, Atwood — see Micrometer, Curves Anglesey, see Population. Animals, a curious marine animal at Virginia, ii. 301 — an uncommon animal voided from the stomach, ii. 539, Lister — methodical arrangement of, iii. 565, Ray — of an undescribed scolopendra marina, iv. 133, Molyneux — from Maryland, iv. 324, Petiver — classification of, according to resemblance of their claws to feet or hands, v. 105, Tyson — skeleton impressed on a stone, vi. 398, Stukeley — on the natural heat of, ix. 148,. Mortimer — structure of the teeth of graminivorous, xviii. 5l9,Home — see Amphibious Animals, Sea Animals, Animalcula, Birds, Fishes, Insects, Quadrupeds, Worms, Zoophyta, Serpents. Animal Flower, see Actinia. Animalcula, in pepper water, &c. iii. 069, King — on their production in water, iv. 89, Harris — that produce the itch, v. 1, Bonomo — discovered on water- weeds, v. 6, 52, 175 ; vi. 42, Leuwenhoek — further particulars of the same, v. 74, .... Anonymous — in the semen of young rams, v. 640, .... Leuwenhoek — nature of spermatic animals, ix. 608, Needham — produced in infusions, x. 698, Wright — account of several marine, xi. 131, Baster — in vegetable infusions, on the increase of, xii. 6l2, Ellis — causing white spots in the Eastern Sea, xiii. 290, Newland — for other animalcula discovered by the microscope, see Leuwenhoek. Annuities, attempt to ascertain the value of, iii. 483, Halley — on Halley's and Buffon's data for calculating, x. 383, Kerseboom — of various sorts, observations on, x. 448, Dodson — table of the value of, constructed upon Dr. Braiken- ridge's plan, xi. 56 — different value, whether paid yearly, or at shorterperiods, xiv. 5, . Price — see Life, Survivorships, Reversions. Anson, Lord, biographical account of, x. 603, Note Anspach, Margrave of, remarkable caves at Bayreuth, and fossil bones found there, xvii. 437 Ants, the different sorts, and observations on, i. 151, King — of a musk-scented pismire, i. 6±9, Lister — abstract of Gould's account of English ants, ix. 298, Miles — description of the termites of Africa, xv. 60, Smeathman — account of the sugar ants, xvi. 6S8, Castles Antelope, description of the Bengal, ix. 145, .... Parsons — description of the Nyl-ghaw, xiii. 117, , Hunter Anthelium, see Parhelion. Antilles, see Caribbee Islands, Currents, APO INDEX. ARD Antimony, effect of, as a medicine for animals, i. 279 — on the efficacy of, i. 596, Kirckringius — vitrification of, by cauk, ii. 183, Lister — process for obtaining the cinnabar of, iii. 232, . . Note — effects of vitrum antim. ceratum, x. 207, .. Geoffroy — observations on the use of, x. 554, Huxham Antiquities, Roman urns and other antiqs. ii. 518, Lister — Roman wall and tower near York, ii. 635, .... Lister — in a well at Kirkbythore, iii. 25, Machel — bridge of St. Esprit in France, iii. 4-2, Robinson — earthen vessel found near York, iii. 167 — figures of rings, amulets, &c. iii. 215 — an ancient sepulchre, found in France, iii. 337, . . Justel — a sepulchre found at Rome, iii. 340, Sarotti — Roman ports and forts in Kent, iii. 521, .... Somner — of a Roman pottery near Leeds, iv. Ill, .. Thoresby — Roman, in Yorkshire, iv. 215, Same — Roman coffin, and other antiquities, iv. 309, . . Same — piece of antiquity found in Somersetshire, iv. 341, 469, Musgrave — Roman antiquities in Lincolnshire, iv. 494, De la Pryme — Roman pots and coins near Devizes, iv. 548, . . Clark — Roman inscriptions and stations, iv. 666, .... Hunter . — found in Lincolnshire, iv. 675, Thoresby — vestige* of a Roman town, near Leeds, iv. 718, Same — a Roman coffin found near York, v. 196, Same , Roman monument in Yorkshire, v. 480, Same Roman antiquities in Yorkshire, v. 487, Same brass weapons found in Yorkshire, v. 510, .... Same — remarks on the above weapons, v. 511, Hearne at Corbridge, Northumberland, v. 632, Todd of a tessellated work at Leicester, v. 644, .... Carte — of Ireland, some account of, v. 694, Lhwyd — of Wales and Scotland, vi. 19, Same , ancient trumpets, &c. found in Ireland, vi. 71 Roman pavement, &c. at Rath, &c. vi. 273, . . Tabor in Sussex, and on the city Anderida, vi. 351, . . Tabor Roman, in Lincolnshire, vi. 660, Thoresby of Prussia, account of several, viii. 420, Klein a Roman torques found in England, viii. 550, Mostyn — an ancient temple and stone hatchet, in Ireland, viii. 714, Bishop of Cork — explanation of some, found in Herts, ix. 118, .. Ward . — Tripos and inscription near Turin, ix. 174, .... Baker — found in Cornwall, xi. 322, Borlase — in Italy, account of several, xi. 473, Venuti — Subterraneous apartments with paintings, &c. at Civita Turchino, in Italy, xi. 706, Wilcox 1 — Roman sepulchral stones found at Bonn, xii. 633 description of some ancient arms and utensils, with ex- periments to ascertain their composition, xviii. 38, Pearson — See Altars, Coins, Hypocaust, Inscriptions, Lamps, Sta- tues, Urns — see Architecture. Anus, Of a whelp voided per anum, iv. 110, ... . Halley — case of a fork thrust up the anus, vii. 125, .... Payne — a fish-bone discharged from a tumour near it, viii. 326, Sherman — See Fat-us Aorta, see Aneurum Aper Americanus moschiferus, see Musk Hog Aphelia, see Planets Aphides, of the different species of, xiii. 120, Richardson Aphyllon, or amblatum, account of, x. 250, .... Watson Apogee, mean motion of the moon's, x. 138, Murdoche, < — See Planets, &c. Aponensian Baths, see Baths Apoplexy, case of, and appearances in the body opened, iii. J84 Cole — affecting the nerves on the side unobstructed, v. 397, Adams Aposthumation of the lungs, cure of, v. 37, Wright ; re- marks on the same, v. 41, Cowper Appetite, account of an extraordinary, iv. 503, Burrough — extraordinary, of a boy, ix. 124, B ix. 126, Cookson Apples, molasses from, vi. 618, Dudley — mixed breed of, from mingling the farina, ix. 599, 685, Cooke — See Liquor, Cyder Appulse, the moon to Jupiter, 1762, at Chelsea, xi. 685, Dunn — See Moon, Planets Aquafortis, mixed with verdigris and leaf-gold, effects on the person mixing it, xi. 66, xii. 83, Baker Aqueduct, for carrying the Eure to Versailles, iii. 167 — further account of, and at Mantenon, iii. 231 Arachidna, oil produced from the plant, xii. 665, Brownrigg Arabian figures, on the antiquity of, ii. 677, Wallis — other opinions on their antiquity, ii. 679, Note — remote antiquity of, in England,- iv. 415, 521, Luffkin — remarks on the antiquity of, viii. 32, 39, Ward — — « viii. 37, Cope — an ancient date in, viii. 478, Barlow — Weidler's dissertation on the use of, ix. 46 Ward — on two ancient dates in, ix. 107, Same — ancient date in Berkshire, ix. 603, Same — see Date. Araliastrum, description of the genus, vi. 314, .. Vaillant Arburthnot, John, m. n., proportion of males and females born, v. 606 — biographical account of, ibid, Note Arbutus andrachne, description of, xii. 403, Ehret Arc, theorem of the hyperbolic arc, xii. 647, .... Landen Arches, luminous, see Light (meteoric) Archimedes, of the burning specula of, x. 488, . . Parsons Archipelago, of a new raised island in the, v. 407, Sherard Architecture, two curious old chimney-pieces, iii. 98, Wallis — problem on the Doric temple at Delos, iii. 479, Wallis — of the ancient Bridewell at Norwich, ix. 167, . . Baker Arcturus, on the proper motion of, xiii. 386, Hornsby Arcuccio, used by nurses in Italy, described, vii. 528, St. John Arderon, Wm., a shuttle spire extracted from the bladder, ix. 83 — sinking of a piece of ground in Norfolk, ix. 169 — description of the weaver's larum, ix. 180 — a water-wheel for mills, ix. 182 — bark a preventive of colds, ix; 184 — keeping of fish in glass-jars ; cheap method of catching fish, ix. 189,322, 511 — an improved hygroscope, ix. 214 — improvement in the weather-cord, ix. 235 — an hygrometer made with a deal rod, ix. 242 — effect of a bristle lodged in a man's foot, ix. 244 — strata ef the cliffs on the Norfolk coast, ix. 272 — perpendicular ascent of eels from water, ix. 311 — observations on the bansticle or prickle back, ix. 322 . gossamer, ibid — on the formation of pebbles, ix. 341 — on the hearing of fishes, ix. 46*5 — large caverns in the chalk hills near Norwich, ix. 490 — present state of a Roman camp in Norfolk, ix. 682 — description of a parhelion, ix. 684 — description of a dwarf, x. 53 ASH INDEX. ATM Arderon, heat of the weather, July 1750, x. 95 — on the severe cold of the winter of 1754, x. 454 — magnetism and polarity of brass, xi. 285 -f- fall of rain at Norwich, 1749—1762, xi. 678 Areas, see Curves. Areometer, description of a new one, vii. 41, Fahrenheit Areometry, essay on, xiv. 387, De Luc Aretina, discovery under ground of the ancient city, viii. 402, Sloane — see Herculancum Arithmetic, account of negativo-afhrmative, vii. 163, Colson — of an arithmetical machine, viii. 25, Gersten — Chinese arithmetical instrument, ix. 624, . . Smethurst — of impossible quantities, xiv. 356, Playfair Arm, torn off by a mill, case of, viii. 226, Eelchier — cure of a fracture retarded by pregnancy, x. 28, . . Barde — remarkable operation on a fractured humerus, xi. 475, White. — extraction and regeneration of part of the bone, xii. 349, LeCat. — - see (Os humeri) . Armadilla, account of the American, xii. 99, .... "Watson Aromatariis, Jos. de, on seeds of plants, generation of animals, iii. 650 Arsenic, and cobalt, way of preparing, v. l65, Kreig Arteries, remarks on the circulation of blood, &c. iv. 6'80, Cow per communications of with the veins, v. 44, Same petrifactions and ossifications of, v. 205, Same , ossification of the crural artery, vi. 538, Naish of two, leading to the ovaria, vii. 163, Ranby — peculiar distribution of, in slowly-moving animals, xviii. 601, Carlisle Arteries, see particular arteries individually. Arteries of leaves (see Leaves). Arthritis, distinctions of, v. 135, Musgrave — see Gout. Articulating cartilages, structure and diseases of, viii. 686, Hunter Articulations, as applied to the alphabet, i. 352, .... Holder Artocarpus, see Bread-fruit Tree. Asa faetida, description of the plant yielding it, xv. 642, Hope Asbestos, found in Wales, paper made of, iii. 105, . . Lloyd — experts, on incombustible cloth, iii. 178, Waite — history and manufacture of incombustible cloth, iii. 179, Plott — of different sorts, and manner of weaving, iv. 604,Ciampini — of a sort found in Scotland, iv. 635, Wilson — v. 671, Blair — on the nature of, xi. 494, Needham — see Amianthus. Ascanius, Peter, m. d., a mountain of iron ore in Sweden, x. 564 Ascites, dissection of a body dead of, iii. 606, Turner — cured by tapping, viii. 729, Banyer — improved method of tapping for, ix. 5, 40, .... Warrick — see Tapping. Asellius, Caspar, biographical notice of, i. 247 Ash, Geo., Bp. of Cloyne, on mathematical demonstrations, iii. 64 — of horns growing on the body of a girl, iii. 229 — force of imagination in pregnant women, iii. 375 — effect of the power of imagination, iii. 375 — of a butter-like dew in Ireland, iv. 78 — low state of the barometer, &c. iv. 303 Ashes, a shower of, in the Archipelago, i. 140, . . Badily ■ at sea 25 leagues from land, x. 6*87, . . Whytt Ashes, see Dust. Asia, observations in parts of, ii. 343, 355, .... Tavernier — merchandize of the Mogul Empire, 356*, Same — Russian discoveries on the h. e. coast of, ix. 320, Euler — distance of, from America, ix. 341 , Dobbs Asperia arteria, peculiar structure of in several birds, xii. 329, Parsons in the land-tortoise, xii. 334, Same Assaying, new method for copper-ore, xiv. 6*08 Asterias Caput Medusae, description of, i. 422, Winthrop Asthma, dissection of a body dead of, v. 705, . . Cowper — ■ xii. 145, Watson — see Breath Aston, Francis, some unknown ancient characters, iii, 574 Astroites, see Star stones. Astronomy, advantage of the earth over other planets for astronomical observation, v. 15, Gregory — on the motion of celestial bodies, vi. 395, .... Demoivre — Newton's tables of astronomical refractions, vi. 519, Halley — advantage of taking mean observations, x. 579, Simpson — method of observing the heavenly bodies out of the meridian, xii. 543, Smeaton — three astronomical problems solved, xiii. 348, Pemberton — on the construction of the heavens, xv. 6ll, 6*80, Herschel — on the chief problems in nautical astrononomy, xviii. 95, Mendoza Rios. — see Eclipse, Parallax, Planets, Stars, Sfc. Astronomical Observations at Ballasore, in India j and corrections of some errors of eminent astronomers, ii. 525, H alley — in China, iv. 233, Cassini — at Wansted, vi. 212, *.-... Pound — at Southwick, vii. 132, Lynn — at Toulon, vii. 144, Laval — at Vera Cruz, vii. 224, Harris — at Pekin, vii. 273, Kogler — at Ingolstadt, vii. 274 — at Pekin, vii. 440, Carbone — at Paraguay, ix. 6l5, 619, Sarmento — at Pekin, x. 2, Hallerstein x. 3, Gaubil — in London, x. 408, Bevis and Short — at Swelzingen, xii. 1 19, Mayer — at Vienna, xii. 220, Liesganig — at Naples and Malta, xii. 554, Zannoni — in Pennsylvania, xii. 578, Mason and Dixon — North America, xii.. 642, xiii. 527, Holland, &c. — at the North Cape, xii. 6*44, Bayley — at Hudson's Bay, xii. 682, ...... Wales and Dymond — near Cavan, xiii. 80, Mason — in the West Indies, xiii. 81, Pingre — at K. Charles's Island, xiii. 174, Green — at Portsmouth, xiii. 276, Witchell — at Pekin, xiii. 492, . Cipolla — in the Austrian Netherlands, xiv. 22, 401, Pigott — at Cork, xiv. 511....... Longtield — in Glamorganshire, xv. 118, Pigott — at Chiselhurst, xiii. 382, 532, 6*50, xv. 519, Wollaston — see Sun, Moon, Venus, Saturn. Atkins, John, meteorological journal at Minebead, 1782, xv. 477 Atmosphere, effect of its changes on the weather, iii. 157, Garden — remarks in reply to the above, iii. 16*2, Wallis — of the moon, remarks on, viii. 371, ......... . Fouchy AUR INDEX. BAD Atrho9phere, experiments in support of the existence of a lunar atmosphere, xi. 644, Dunn — cause of the haziness of, in hot weather, xii. 227, Franklin — peculiar electricity of, Oct. 1775, xiv. 60, . . . . Cavallo — effects of effluvia on the, xiv. 322, White •—its effects on the heat of boiling water, xiv. 537, Shuckburgh — relative quantity of its moisture absorbed by various sub- stances, xvi. 260, Rumford — effect* of atmospherical refractions on astronomical observ,, xii. 152, xvi. 221, Maskelyne — ■ on refractions of, xviii. 436, Vince — double images by atmospherical refraction, xviii. 667, Wollaston — see Air. Atkinson, Joseph, an imposthumation in the stomach, vi. 579 — extraordinary case of tumours, vii. 97 Attraction, Wallis's approach to the idea of universal, i. 102, Note — laws of, v. 417, Keill — figure of revolving fluids, vii. 519, Maupertuis — - point of, between the sun and a comet, xii. 405,Winthorp — on the attraction of hills, xiii. 700, Maskelyne ■ Mount Schehallien, xiii. 702, Same — point of greatest attraction in a hill, xiv. 603, . . Hutton — resolution of attractive powers, 572, Waring — see Magnet. Attraction, (Chemistry) attractive powers of various saline bodies, xvi. 236, Kirwan Attrition, of bodies in vacuo, experts, on, v. 270, Hauksbee — of glass, electricity by, v. 307, 324, 344, 355, 41 1, Same — of several bodies productive of electricity, v. 413, Same — production of light by, xvii. 128, 215, Wedgwood Atwell, Joseph, d. d., cause of intermitting springs, vii. 544 — experiments on persons bitten by vipers, viii. 107 Atwood, George, the mensuration of an angle, xv. 133 — on the times of vibration of watch balances, xvii. 380 — theory of floating bodies j stability of ships, xvii. 682 ; xviii. 315 Aubert, Alexander, biographical account of, xii. 665, Note — observation of the transit of Venus, 1769, in London, xii. 665 — on finding time by equal altitudes, xiii. 734 — observations of meteors, Aug. and Oct. 1783, xv. 479 Aubry, Mr., of a medicated springin Glamorganshire, iv. 21 1 Aurora australis, seen at Rome, 1740, viii. 502, . . Revillas ■ ■ London, 1739, viii. 525, Mortimer — — -— — - Chelsea, ibid, Martyn ■ viii. 526, . . Neve. — — — — Chelsea, 1750, x. 3, . . .. Martyn Aurora borealis, observ. of two in Kent, vi. 290, . . Barrell — seen in London, March, 1717* vi. 291, Folkes November, 1719, vi. 441 Halley — same at other places, vi. 442 — four years observations, vi. 645 — observed at Upsal, vii. 54, Burrman — in Ireland, September, 1725, vii. 155, Dobbs — at Petworth, October, 1726, vii. 157, Langwith — at Plymouth, vii. 158, " Huxham — at Exeter, ibid, Hallet — at Geneva, vii. 159, Calandrini — October, 1726, remarks on, vii. 183, Derham — observations of, for 4 years at Lynn, vii. 185,. . Rastrick — observed at Southwick, October, 1726, ibid, Lynn — at several times, vii. 194, Langwith -^- at Liverpool, January, 1727, vii. 195 Aurora borealis, at several places, October, 1726, vii. 238 — uncommon appearances in, vii. 351, ,. Derham — observed, October, 1728, vii. 384, Weidler — an unusual one at Geneva, vii. 393, Cramer — in New England, October, 1730, vii. 463, . . Greenwood — in Maryland, ■ ■ ■- vii. 464, Lewis — inquiry into the cause of, vii. 637, Mairan atWittemberg, Feb.& Oct. 1732, vii. 6*4, Weidler — observations made on, viii. 69, Celsius — in Huntingdonshire, Dec. 1735, viii. 134, .... Neve — in Edinburgh, November, 1736, viii. 412, Short — at Chelsea, February, 1750, x. 12, Martyn — January, 1751, ibid, Miles — account of several, x. 63, Baker Hague, 1750, x. 134, Gabre — on the cause of, and influence on the magnetic needle, xi. 421, Canton — at Philadelphia, 1757, xi. 614, Bartram London, the same, ibid, Franklin — two observed at Paris, 1768, xii. 6l 1, Messier Oxford, l769,xii.66l,xiii.88,..Swinton — on the weather preceding and following, xiii. 512. Winn — see Light (Meteoric) Mtteors. Aurum Mosaicum, apparatus for making, xiii. 106, Woulfe Avoirdupois, the standard of English weights, ix. 637, Reynaidson — see Weights Averrhoa Carambola, sensitive qualities of, xvi. 10, Bruce Austin, Wm., M. D., on the formation of volatile alkali j and the affinities of phlogisticated and light inflammable airs, xvi. 493 — analysis of the heavy inflammable air, xvi. 632 Authors, method of discovering the age of, by their style, v. 227, Wanley — a list of, on the theory of rivers, xiv. 593, .... Mann Axis, observations on Perault's axis in peritriochio, vii. 377, 380, Desaguliers — see Earth, Jupiter, Planets, Syc. Auzout, Adrian, some account of, i. 3, Note — motion of the comet of 1664 predicted, i. 3 — on Cassini's hypothesis respecting it, i. 9 — course of the comet of 1665, i. 14 — table of the apertures of object glasses, i. 22 — controv. with Hook on the grinding of object glasses, i. 2 — illuminating an object to any degree, i. 23 — distance requisite to burn bodies by the sun, i. 23 — superiority of Campani's glasses, i. 24 — on the satellites of jupiter, i. 25 — hypothesis of changes in the moon and earth, to be seen by their respective inhabitants, i. 41 j verified by the subsequent discoveries of Herschell, i. 42, Note — measuring of distances by the telescope, i, 43 — account of shining worms in oysters, i. 67 — diameter of the sun, and parallax of the moon, i. 138 — magnetical variations at Rome, i. 434 Aylett, George, observation of a spina bifida, ix. 5 Azimuth compass, a new one for finding the variation of the needle at sea, viii. 25 1, Middleton B Babin, J. P., flux and reflux of the Euripus, i. 592 Bacon, Vincent, a man poisoned by the napellus, vii. 642 Badcock, R., microscop. observations of the farina of the holly-hock, and passion-flower, ix. 230, 234 — on the farina fcecundans of the yew-tree, ix. 243 Badenach, James, M. D., description of the violaceous par- tridge of Malacca, xiii. 267 Badily, Wm , a shower of ashes in the archipelago, i. 140 B A.R INDEX. BAR Bagford, John, on the invention of printing, v. 350 Bahama Islands, of poisonous fish at, ii. 213 Bailey, Edw., M. D., stone in the colon of a horse, ix. 278 — ■ stones in the intestines of a mare, ix. 279 Bailly, John Sylvain, biographical account of, xiii. 429, Note — on perfecting the theory of Jupiter's satellites, xiii. 422 Baillie, Matthew, M. D., case of transposed viscera, xvi. 483 — on the formation of hair, &c. in the ovarium, xvi. 535 Baker David Erskine, a tripos and inscription, ix. 174 — property of water-efts to slip off their skins, ix. 349 — • two extraordinary belemnites, ix. 597 — comparison of a dwarf with a child of 4 years, x. 53 — an earthquake at York, 1754, x. 469 Baker, Henry, biographical account of, viii. 4:6 .... Note — a beetle which lived 3 years without food, ibid. — discovery of a plant in the seed, viii. 429 — description of Leuwenhoek's microscopes, viii. 443 ; fo- cusses compared with those of Mr. Folkes, 444, 445 — virtue of black currants for a sore throat, viii. 479 — of a woman who spoke after losing her tongue, viii. 586 — observations on a dried polypus, viii. 725 — description of the eye-sucker, ix. 15 — method of procuring the impression of coins, &c. ix. 30 — large fossil elephant's tooth, ix. 110 — architecture of the Bridewell at Norwich, ix. l67 — a curious echinites, ix. 326 — clay moulds for Roman coins, ix. 356 — grass in Norfolk destroyed by grubs, ix. 366 — of the fish called quab in Russia, ix. 470 — experiments in medical electricity, ix. 497 — description of a fossil nautilus, ix. 632 — microscope observ. on minute seeds of plants, x. 8 — account of several aurora; boreales, x. 63 — a fire-ball seen in the air, July 1750, x. 126 — some uncommon fossil bodies, x. 347 — case of disordered skin, x. 562 — - effect of the opuntia and of indigo in colouring the juices of living animals, xi. 137 — description of the American cuttle-fish, xi. 286 — calculus taken from the colon of a horse, xi. 484 — account of Torre's microscope glasses presented to R. s. xii. 287 Baker, Thomas, a wound in the cornea of the eye, viii. 324 Balance, proposition respecting the balance, viii. 348, Desaguliers — paradox relating to the, vii. 482, Same — a new balance for thread, xii. 233, Ludlam Balcarras, Earl, dissection of the body of, i. 30 Baldwin, Christianus Adolph., biograph. account of, ii. 368 — accidental discovery of a species of phosphorus, ii. 368 Balguy, Chas., m. d., dead bodies preserved from decay in peat-moss, vii. 666 Ball, Wm., method of preserving ice with chaff, i. 50 — observation of two rings of Saturn, i. 54 Ballard, Mr., on the magnetism of drills, iv. 332 Ballasore, astronomical observations at, ii. 525, . .Halley Banister, John, biographical account of, iii. 515, Note — account of several insects in Virginia, iv. 565 Banyer, Henry, m.d., extraordinary haemorrhage, viii. 727 — ascites cured by tapping, viii. 729 Barbadoes, remarks on the Nat. Hist, of, ii. 228,. . Towns Barbary, some characteristics of the Moors of, iv. 407, Jones Barbosa, J. M. S., lunar eclipse, 1755, at Elbing, x. 621 Barde, John, cure of a fractured arm retarded by pregnancy, x. 28 Barham, Henry, meteoric stone in Jamaica, vi. 368 — production of silk worms in England, vi. 426 Bark, (Peruvian) opposition to its use, iii. 534, . . Morton Bark, (Peruvian) of the tree producing it, v. 119, ..Oliver — microscopical observations on, v. 372, .... Leuwenhoek — of its efficacy in mortifications, vii. 572, .... Douglas — __ — _ _____ vii. 574, .... Shipton — first used in cases of mortification by Mr. Rushworth, vii. 574, Note — account of the Peruvian bark tree, viii. 14?, .... Gray — preventive of colds, ix. 184, Arderon — use of, in the small pox, ix. 369, "Wall — - efficacy of, in mortification, xi. 159, Grindall — in the delirium of fever, xi. 235, Munckley — description of the bark tree of Jamaica, xiv. 199, Wright — cabbage bark tree of Jamaica, xiv. 200, Same — descript. of the bark tree of St. Lucia, xv. 619, Davidson — (of willow) efficacy of, in agues, xii. 1, Stone Barks, effects of cutting, i. 305, 306, Beale, Tonge — season and method of barking, iii. 420, Plott — observs. of the growth and texture of, v. 188, Leuwenhoek — of the quantity of tanning principle and gallic acid in various barks, xviii. 527, Biggin Barker, Robert, a catoptric microscope, viii. 73 — Sir Robert, thermometrical observations at Allahabad, 1767, and on a voyage to England, 1774, xiii. 631 — general state of the weather at Bengal, xiii. 632 — process of making ice in the East Indies, xiii. 643 — description of the Benares Observatory, xiv. 214 Barker, Rev. Robert, horns and head of a large stag found i n Derbyshire, xvi. 9 Barker, Thomas, biographical notice of, x. 645, . . v . Note — meteor seen in Rutland, 1749, ix. 698 — calculation of the return of a comet, x. 645 — on the mutations of the stars, xi. 432 — of a remarkable halo, xi. 514 — plan of his rain-gage, ibid, xiii. 131 — meteorological observations, at Lyndon, &c, xiii. 131; for 1771, 277; 1773, 530; 1774, 631; 1775, xiv. 48; 1776,178; 1777,389; 1778,592; 1779,711; 1780, xv. 118; 1781, 277; 1782, 396; 1783,543; 1784, xvi. 30; 1785, 95; 1786, 306; 1787, 507; 1788, 563; 1789, xvii. 28: 1790, 74 * 1791, 242; 1792, 335; 1793, 392; 1794,613; 1795, xviii. 64; 1796, 300; 1797, 442; 1798, 580 — separation of salt from salt water by freezing, xiv. 48 — on the annual growth of trees, xvi. 507 — discovery of a chalk-pit in Rutland, xvii. 75 — on the recovery of injured trees, xviii. 442 Barlow, Rev. Wm., population and mortality at Stoke- Damerel, viii. 53 — of the sun-fish, and glue made of it, viii. 402 — analogy of English weights and measures, viii. 432 — an ancient date in Arabian figures, viii. 478 Barnacles, description of, ii. 415, Moray; correction of an erroneous opinion respecting them, 4l6, Note — description of some rare species of, xi. 307, Ellis Barnard, Wm., method of saving a stranded ship, xiv. 625 Barometer, accountof the, and observns. with, i. 54, 57, Beal — observations on the baromer, i. 60 — directions for making observations with, i. 62, . . Boyle — a new wheel-barometer, i. 72, ............ Hook — measuring of heights by, not a recent discovery, i. 80, note — and thermometer, observations with, i. 415, Beale , — , 416 Wallis — the running of sap, a good barometer, i. 559, . . Tonge — cause of the suspension of mercury at the top of a small tube, ii. 1, Huygens ; otherwise accounted for, 3, Note — cause of the suspension of mercury, ii. 44,. . . . Wallis — on the rise and fall of mercury in it, iii. 9^> Lister — heightof the mercury at differ, elevations, iii. 300, Halley BAR INDEX. BAY Barometer, on increasing the divisions of, iii. 343, . . Hook — observations on, at Jamaica, iv. 79, Beeston — trial of the Torricellian expt. on Snowden, iv, 174, Halley — . on the monument, iv. 225,. . Derham — to make a portable barometer, iv. 226, Same — measuring the height of mercury by a circular plate, iv. 231, Same — on enlarging the divisions of, iv. 269, Gray — 'low state of, iv. 303, Ashe — observation on the height of mercury in, iv. 349, Derham — altitude of the mercury in China, iv. 426, . . Cunninghame — height of the mercury, l699> iv- 483, Derham — remarks on Hook's marine barometer, iv. 56l . . Halley — of a new baroscope, v. 120 Caswell — cause ©f the mercurial descent in a storm, v. 147, Hauksbee — expts. with in difft. parts of Switzerl., vi. 166, Scheuchzer — cause of the variation of, vi. 283, Desaguliers — the measuring of heights by, vi. 496, Halley — extraordinary height of, vi. 537, Graham — observations in 1723, vii. 2, Cruquius — height of, at different elevations, vii. 86, .... Nettleton — aa experiment with, vii. 89, Celsius — on measuring of heights by, vii. 264, .... Scheuchzer — of a new barometer, vii. 590 Rowning — cause of the rising, &c. of mercury in, vii. 592, Gersten — in a storm, observations on, viii. 78, Forth — Mr. Orme's improvement of, viii. 198, Beighton — rules for foretelling the weather by, viii. 202 — observs. of differences in heights, viii. 5/8, . . Hollman — on its agreement with the weather, ix. 651, .... Same — a new portable barometer, xii. 201, Spry — improvements of a wheel barometer, xiii. 17, Fitzgerald — the measuring of heights by, xiii. 145, Pigott — De Luc's rule for measuring heights, adapted to Faren- heit's thermometer, and the English measure, xiii. 520, Maskelyne — measurement of the depth of the mines of Hartz by, xiv. 180, 574, De Luc — description of that used by the r. s. xiv. 52, . . Cavendish — ■ admeasurem. of weights in Savoy, xiv. 203, Shuckborgh — on the measurement of heights by, xiv. 226, .... Roy — description of a thermometrical barom.,xv. 164,. . Cavallo — see Heights. — Meteorological Observations Baroscope, on a new statical baroscope, i. 77, .... Boyle — See Barometer Barr, Mr., journal of the weather at Montreal, 1777, xiv. 389, 681 Barrattier, (John,) of the early genius of, xiii. 13, Bar- rington Barrel, Rev., Edm., on the propagation of misleto, vii. 176 — shock of an earthquake in Kent, vii. 195 — difference of sex in misleto, vii. 271 Barrenness, Bath waters a cure for, iii. 140, Peirce Barrington, Hon., Daines, biograph. account of, xii. 421 — of singularly shaped perch and trout in Wales, ibid. — on the change of climate in Italy, &c. from what it was 17 centuries ago, xii. 508 — of the indigenous trees of Britain, xii. 594 — of the early musical genius of Mozart, xiii. 11 — chesnut trees not indigenous in Britain, xiii, 116 ■ — account of a mole from North America, xiii. 148 — fall of rain different at different heights, ibid. — of sea-fish found in fresh water, xiii. 154, Note — specific characters distinguishing the rabbit from the hare, xiii. 267 — on the migration of birds, xiii. 314 — a curious fossil found near Christchurch, xiii. 418 Barrington, on the nat. history of the ptarmigan, xiii. 433 — observations on the singing of birds, xiii. 442 — of the gillaroo trout, xiii. 509 Barros, M. de, observation on a transit of mercury, x. 426 Barrow, Isaac, d. d., biographical account of, i. 633 . . Note Barrows, examination of, in Cornwall, viii. 433, Williams — near Bridgnorth, viii. 582 Stackhouse Bartholine, Erasmus, biographical notice of, i. 403, . . Note — exper. on a crystal-like body, from Iceland, i. 545 Bartholine, Caspar, some account of, ii. 360 — on the salivary vessels, iii. 86. Bartholine, Thomas, biographical notice of, i. 247 Bartram, John, on the teeth of the rattle-snake,* viii. 409 — salt and fresh- water muscles of Pennsylvania, ix. 70 — oysters and oyster-banks of Pennsylvania, ibid. — wasps' nests of clay in Pennsylvania, ix. 123 — of the black wasp of Pennsylvania, ix. 699 — of the libella or dragon fly of Pennsylvania, x. 4, 28 — an aurora borealis at Philadelphia, 1757, xi. 614 — of the yellow wasp of Pennsylvania, xi. 685 Barytes, chemical experiments on, xv. 544 .... Withering Bas-relief of Mithras found at York, ix. 687 .... Stukely Basaltes, in several parts of Germany, x. 703 . . Trembley — Basaltic hills in Hessia, xiii. 222, Raspe — of Basaltic columns in Italy, and on their origin, xiii. 577, 677, Strange — affinity between it and Granite, xvii. 8, Beddoes — See Giant's Causeway. Basil, of remarkable mineral springs at, i. 47 Bastar, Job, m.d., description of the teredo navalis, viii. 37$ — pendulous tumour on an infant's back, viii. 622 — dissection of a child dead of hydrocephalus, ibid. — a foetus with no distinction of sex, x. 57 — of marine animalcula ; nature of corallines, &c. xi. 131 — figures of zoophytes, xi. 537 Bastard, Win,, on the culture of pine apples, xiv. 224 Bate, George, m.d., biographical notice of, iii. 601, Note Bate, James, m.d., change of colour in a negro-woman, xi. 370 Bates, Thomas, distemper among the cows near London, 1714, vi. 375 Bath, (City) particulars of, especially the waters, i. 36l, Glanvil — effect of the waters in curing palsy, &c. iii. 140, . . Plott — degrees of heat of the waters, xii. 419, Howard xii. 420, Canton Baths, description of, in Austria and Hungary, i. 405, Brown — ceremony of bathing at Buda, i. 455 — of the Aponensian baths, i. 720, Doddington — of the hot-baths of Vinadio, xi. 495, Bruni — see Waters {Mineral and Medicinal) . Baxter, Wm., on the hypocausts of the ancients, v. 291 — halos and parhelia seen in North America, xvi. 1 80 Bayes, Rev. Thomas, on certain infinite series, xii. 14 — a problem in the doctrine of chances, xii. 41, 160 Bayle, Francis, m. d., biographical notice of, ii. 435 — an extra-uterine feetus, ii. 435 Bayles, John, his death and dissection at 130 years old, v. 299 Keill Bayley, Edw., m. d., earthquake at Havant, 1734, viii. 96 Bayley, Joel, transit of Venus and solar eclipe, 1769, at North Cape, xii. 644 j going of a clock at the same place, ibid — transit of Venus, 1769, in Pennsylvania, xii. 673 Baynard, Edward, m. d., cause of pain in rheumatism, iv. 9 — cure of suppression of urine by acids, iv. 10 — effect of swallowing copper farthings, iv. 335 10 BEE INDEX. BER Bayreuth, some remarkable caves at, and fossil bones, xvii. 437, Margrave of Anspach Beale, J., d. d., biographical account of, i. 415, .... Note — of the barometer, and observ. with, i. 54, 57 — experiments on shining fish, i. 75 — on petrifactions, i. 119 — an operation for the stone, i. 120 — promiscuous observations in Somersetshire, i. 121 — efficacy of the Malvern water, i. 132 — the salt springs of Droitwich andNantwich, i. 132 — proposal for experiments with the air-pump, i. 150 — on vegetation and the running of sap, i. 304 — connection of parts of a tree with the fruit, i. 334 — observation on the baroscope and thermoscope, i. 415 — on the origin of mineral springs, i. 420 — on the generation of minerals, &c. ibid — reflections on medicinal springs, i. 423 — considerations on apple-trees, planting, &c. i. 589 — use of salt j on sheep, ii. 133 — miscellaneous remarks, ii. 220 — remarks on the Vinetum Britannicum, ii. 288 ————— shining flesh, ii. 294 — agrestic observations, ii. 374, 384 Beans, four sorts from Jamaica cast on shore in Scotland, iv. 103, . . Sloane Bear, anatomical description of the, i. 372 Beard, R., m. d., of a person killed by lightning, vii. 153 — stone voided by a woman by the urinary passage, vii. 175 Beasts, see Quadrupeds. Beatification, see Electricity. Beauchamp, Lord, explosion of a fire ball, viii. 540 Beaumont, John, growth of rock plants, ii. 351, 647 — on fire-damps in mines, ii. 474 — account of the caves about the Mendip Hills, ii. 487 — on cleaving rocks with gunpowder, iii. 113 Beaver, anatomical description of the, i. 371 — natural history and dissection of, vii. 623, .... Mortimer — two species from Hudson's Bay, xiii. 326, Forster Beccaria, J., Baptist, biograph. notice of, xii, 291, . . Note — experiments in electricity, xi. 435 — of double refractions in crystals, xi. 6l5 — experiments in electricity, xii, 291 1 445 — on electrical atmospheres, xiii. 50 — colours emitted by phosphorus, xiii. 130 Becher, Joachim, biographical account of, i. 620 Becke, D., Van Der, volatilization of salt of tartar, ii. 54 Beckett, Wm., antiquity of the venereal disease, vi. 368, 467, 492 — difference in the height of the human body at morning and at night, vii. 25 Beckman, John Christopher, account of osteocolla, i. 278 of an unusual kind of snow, i. 279 Beddoes, Thomas, m. d., experiments on the production of cold, xvi. 279 — affinity between basaltes and granite, xvii. 8 — conversion of cast into malleable iron, xvii. 47» 209 Beech Tree, letters found in the centre of, viii. 359, Klein Bee-hive, of a sort used in Scotland, ii. 82 Bees, on an early swarm, i. 580, Reed — a strange sort of, at Cayenne, iii. 171 — natural history and economy of, x. 78, Dobbs — a specimen of the apis willughbiella, xi. 496, . . Styles — discoveries on the sex of, xiv. 125, Debraw — remarks on Mr. Debraw's observations, xiv. 304, Polhill — natural history and economy of, xvii. 155, . . ..Hunter — see Gall-bee, Insects, Honey. Beeston, Sir William, on the barometer, iv. 79 — efficacy of a hot bath in Jamaica, iv. 79 Beetle, of a species with horns like a stag's, ii. 311 — on the numerous eyes of, iv. 26*8, Leuwenhoek — which lived three years without food. viii. 426,. . Baker — found alive in a cavity of sound wood, viii. 535,Mortimer Behm, Michael, remarks on the serum of blood j on gout j the spleen, &c. i. 237 Beighton, Henry, biographical account of, rii. 442, . . Note — of the London-bridge water- works, vii. 442 — Mr. Orme's improvement of the barometer, viii. 198 — a new plotting- table, viii. 502 Belcher, Mrs., agitation of the waters of the Ontario, x. 695 Belchier, John, case of hydrops ovarii, vii. 533 — bones tinctured red by aliment, viii. 79, 83 — case of an arm torn off by a mill, viii. 226 Belemnites, origin and varieties of, ix. 311, .... Da Costa — description of two extraordinary, ix. 599, Cooke — description of various, x. 542, Brander — origin and formation of, xii. 91* Plott Belius, [Bell] Matthew, copper waters of the mines in Hungary, viii. 236 — of an icy, and a noxious cavern in Hungary, viii. 293 Bell for Diving, see Diving. Bell, George, dissection of a body dead of stone, viii. 557 Bell, William, of the double- horned rhinoceros of Sumatra, xvii. 282 — description of the chaetodon ecan bonna, xvii. 284 Bellers, Fettiplace, strata of a coal mine, v. 707 Bellini, Laurence, biographical account of, i. 135 — anatomical engagements of, i. 531 Bellows, an improvement of the Hessian, v. 226, . . . Papin — a centrifugal bellows for ventilations, viii. 12,Desaguliers — a new water-bellows, viii. 192, Triewald ix. 169, Stirling Belluga-stone, account of the, ix. 335, Collinson — for Belluga-fish, see Acipenser huso. Belly, see Fcetus, Tumours. Belt, see Jupiter, Saturn. Benares Observatory, see Observatory. Benares, method of making ice at, xvii. 294, 305, Williams Benevoli, Antonio, observations on the cataract, vi. 602 Benjamin-tree, [Styrax Benzoin] description of, xvi. 287, Dryander Bennet, Abraham, a new electrometer, xvi. 173, 176 — account of a doubler of electricity, xvi. 282 — new suspension of the magnetic needle, xvii. 142 — polarity of brass and iron filings, xvii. 145 Bent, Thomas, method of making tar rosin, &c. near Mar- seilles, iv. 302 — James, the use of the right arm recovered after the loss of the os humeri, xiii. 539 Benvenuti, Joseph, m. d., remarkable recovery from fever, xii. 551 — case of an uncommon large head, ibid Bengal, heat of the climate of, xii. 423, Martin Bergius, P. J., description of the plant croton lucidum, xii. 529 — description of the nyctanthes elongata, xiii. 147 — plants of the Brownaea genus, xiii. 419 Bergman, Torbern, biographical account of, xi. 506, Note — degree of the electricity of water, ibid — transit of Venus over the sun, 1761, xi. 564 — observations of auroras boreales in Sweden, xi. 615 — experiments in electricity with crystal, xi. 705 — letter to Mr. Wilson on electricity, xii. 109 — electric nature of the tourmalin, xii. 343 Berkley, Edward, eruption of Vesuvius, 1717* vi. 3l6 Berkley, George, d. d., biographical notice of, ix. 288 — of tie petrifying quality of Lough Neagh, ibid BIL INDEX. BLA 11 Bermudas, account of the whale fishery, i. 6, 46,. . A seaman — of the tide, water, and whale fishery at, i. 206, Norwood — the whales, tides, spiders, longevity, &c, i. 283, Stafford — of a berry equal to cochineal for dyeing, i. 284 Bernacle, [anas erythropus] description of, iii. 173, Robinson Bernard, Chas., stones cut from the urethra, iv. 86* Bernard, Rev. Edw., biographical account of, iii. 75, Note — longitudes, &c. of the chief fixed stars, iii. 31 — opinion of ancients on the obliquity of the ecliptic, iii. 75 Bernard, Wm., explosion of air in a coal-pit, xiii. 432 Bernoulli, Nich. biographical notice of, vi. 98, Note — on a problem of the doctrine of chances, ibid Bernoulli, James, biographical account of, ii. 546, . . Note — cause and motion of comets, ibid Bernoulli, John, biographical account of, iv. 129, • • • • Note — solution of his problem on curves, v. 90, Craig — apology against the accusations of, vi. 397, Taylor Belts, Rev. Joseph, computation of comets' motions, ix. 47 Bevan, Sylvanus, case of bones becoming flexible, viU. 682 Beurer, J. Ambrose, nature of amber, viii. 631 — on osteocolla, ix. 126 Bevis, John, m.d., biographical account of, viii. 117, Note — lunar eclipse, London, viii. 1 17, 147, ix. 567, 698, x. 95, xi. 632, xii. 1 13 — transit of Aldebaran over the moon, 1736, London, viii. 147 — solar eclipse, London, viii. 148, 169, ix. 567, x. 409, xii. 112 — occultation of Mars by the moon, 1736, ibid Mercury by Venus, 1737, viii. 251 — - a luminous appearance in the sky, 1735, viii. 404 — conjunction of Venus with Mercury, 1737, viii. 470 — occult, of Jupiter and his satellites by the moon, viii. 477 — transit of Merc, London, Oct. 1736 and 1743, viii. 725 — observations of the planet Mercury, ix. 41 — occultation of Cor Leonis by the moon, ix. 336 • Venus by the moon, 1751, x. 174 — of Mr. Gascoigne's invention of the micrometer, x. 369 — Venus eclipsed by the moon, x. 408 — Mars eclipsed by the moon, ibid — account of" the comet seen May 1759, xi. 337 — latitude of the observatory at Vienna, xii. 220 — state of the thermometer Jan. 1740 and 1768, xii. 507 — transit of Venus and solar eslipse, 1769, at Kew, xii. 631 Bewick, Benj., of the earthquake, Nov. 1755, at Cadiz, x. 662 Bezoar stone, how produced, ii. 356, Tavernier — of the rhinoceros bezoar, ix. 655, Sloane Bianchini, Francis, biographical account of, iii. 135, Note — astronomical observations at Rome, vi. 92 — observations of the comet of 1723 at Albano, vii. 16 — lunar eclipse, Rome, Oct. 1724, vii. 165 Albano, Oct. 1725, ibid — eclipses of Jupiter's satellites, ibid — observation of the lunar spot Plato, vii. 166 — observations of Jupiter's satellites at Rome, vii. 335 — account of the death of the Countess Zangari, ix. 138 Biddle, Owen, transit of Venus, 1769, in Pennsylvania, xii. 673 Bidens tripartita, mistaken for an aquatic animal, viii. 674 Miles Bidloo, Godfrey, biographical account of, iii. 260. . . . Note Biggin, George, of Uie tanning principle aud gallic acid in various barks, xviii. 527 Bile, from different dead bodies, experiments on, vi. 557, 561, 586, Deidier — use of, in the animal economy, vii. 407, 577, . . Stuart — see Gall- Bladder, Biliary ducts, on the obstruction of, viii. 228, .... Amyand Bills of mortality, see Mortality, Population. Billy, J. de, biographical notice of, i. 121 Note — method of finding the Julian year, ibid; demonstrated by Mr. John Collins, i. 207 Bils, Louis de, biographical notice of, i. 283, Note — on the use of the lymphatic vessels, ibid Binomial theorem, demonstration of, xvii. 573 . . Robertson Biornius, Paul, account of Iceland, ii. 187 Biquadratic equations, see Equations. Birbeck, Christ., of a foetus voided by the navel, iv. 634 Birch, (tree) quantity of liquor to be drawn from in spring, i. 304 Birch, Sampson, a strange uterine production, ii. 649 Birch, Thos., d. d., biographical account of, x. 446, Not* — Roman inscription at Durham, ix. 470 — on the luminousness of electricity, x. 446 — agitation of the waters at Peerless Pool, x. 650 — remarks on the black assize at Oxford, xi. 264 Birds, of the humming bird ; man of war bird, &c., i. 23 1 , Note — on the natural history of, ii. 252, "Willoughby — anatomical observations on the heads of, iii. 531, Moulen — on the migration of, v. 425, Derhani — of passage, remarks on, ix. 327* Catesby — method of stuffing, for specimens, ix. 506, ..Reaumur — bird bred between a turkey and pheasant, xi. 493, Edwards — method of preserving for specimens, xiii. 34, . . Davies xiii. 50, Kuckahn — observations on the singing of, xiii. 442 j comparative table of their musical powers, 448, Barrington — on the structure of the eyes of, xvii. 557, Smith — see Albatross, Bernacle, Bunting, Bustard, Cuculus In- dicator, Cuckoo, Cassowary, Columba cristata, Cormo- rant, Crane, Crow, Cuntur, [Condor] Eagle, Finch, Fla- mingo, Fly-catcher, Goose, Grebe, Grosbeak, Grouse, Gull, Hawk, Humming bird, Indian cock, Lark, Ma- creuse, Ostrich, Otis, Owl, Paroquet, Partridge, Pelican, Penguin, Pheasant, Pigeon, Pintado, Ptarmagan, Reed- wreen, Sand-piper, Shrike, Snipe, Swallow, Swan, Tern, Thrush, Titmouse, Vulture, Wagtail, Woodcock, Wood- pecker. Birth, a strange uterine production, ii. 648, Birch — proportion of males and females born, v. 606, Arbuthnot — cases of numerous births, xvi. 294, Garthshore — see Child, Monsters, Parturition, Bitch, experts, of injecting liquor into the thorax of, iv . 271, Musgrave Bite, see Vipers, Rattlesnake, Dog, Mad Animals, Hydro- phobia. Bitumen, a sort found in Sicily, ii. 117 — of a bituminous plain in Trinidad, xvi. 531, . . Anderson Bivalve insects, description of some monoculi, xiii. 132, Muller Black, see Dyeing. Black assize, at Oxford, account of, xi. 263, .... Ward remarks on, xi. 264, Birch Black lead, on the nature of, iv. 272, Plott, and Note Black vomit, of South America, accountof, ix. 665, Watson Black, Jos.,m. d. biographical account of, xiii. 6*10, Note — experiments on the freezing of boiled water, xiii. 6l0 Bladder, of a bullet voided with urine, i. 286, .... Fairfax — operation of cutting a bodkin from the, iv. 468, Proby — case of a triple bladder, iv. 545, Bussiere — unusual formation of the urinary parts, vii. 352, Bugden — a pin taken from a child's bladder, viii. 239, Gregory — an extraordinary stone cut from, after death, viii. 240, Marquis de Caumont B2 12 BLO INDEX. BOH Bladder, account of the preceding case, viii. 241, . . Salien — observations respecting the above stone, viii. 24-2, Sloane — a shuttle spire extracted from the, ix. 83, ... . Arderon — extirpation of a tumour from the inside of, x. 32, Warner — on fungous excrescences of the, x. 214, Le Cat — see Stone, Urine. — for bladders of fish, see Fish. Blagden, Charles, m. d., on the power of the body to resist heat, xiii. 604, 695 — heat of the water of the gulf-stream, xv. 115 — effects of lightning at Heckingham, xv. 306 — history of experts, on mercurial congelation, xv. 431 — account of meteors, with observ. on their nature, xv. 520 — on ancient inks, and on recovering the legibility of decayed writings, xvi. 351 — on cooling of water below the freezing point, xvi. 409 — on lowering the point of congelation, xvi. 459 — best method of proportioning the excise on spirituous li- quors, xvi. 675, xvii. 263 — on the tides at Naples, xvii. 318 Blair, John, l. l. d., agitation of the waters near Beading, 1755, x. 651 Blair, Pat., m.d., natural history and anatomy of the ele- phant^. 557, vi. 382 — of asbestos found in Scotland, v. 67 1 — dissection of an emaciated child, vi. 307 — organ of hearing of an elephant, vi. 382 — of a boy living 3 years without food, vi. 459 — discovery of the virtues of plants from their structure, vi. 459 — observations of the generation of plants, vi. 534 Blake, Francis, biographical notice of, x. 1 87, Note — best proportions of steam-engine cylinders, ibid — reduction of spherical trigonometry to plane, x. 255 — on the greatest effect of engines, xi. 317 Blake, John, lunar eclipse at Canton, 1772, xiii. 493 Bland, Robert, m.d., calculation of the number of acci- dents attendant on parturition ; proportion of male and female children born ; of twins, monsters, &c. xv. 118 — table of the chance of life from infancy to 26 years, xv. 122 of the natives of London compared with its actual inhabitants, xv. 123 Blane, Gilbert, m. d., account of the nardus Indica, xvi. 658 Blane, Win., Esq., on the production of borax, xvi. 282 Blasius, Gerard, biographical notice ef, i. 148, .... Note Blindness, see Vision, Eye. Bliss, Nathaniel, transit of Venus, June I76l, at Green- wich, xi. 552 general deduction from the different observations of the same transit, xi. 564 — observ. of a solar eclipse at Oxford, 1764, xii. 115 Blister, operation- of, in the cure of fever, iv. 378. Cockburn — cases of the good effects of, in coughs, xi. 220, Whytt Blizard, William, new method of treating the fistula lachry- malis, xiv. 679 Blon, James Christopher le, principles of printing in imi- tation of painting, vii. 477 Blondeau, paintings found at Herculaneum, ix. 620 Blondel, Francis, biographical account of, ii. 274, . . Note — proceedings of the Royal Academy at Paris, iv. 651 Blood, of a milky appearance, i. 38, 41 : the same ac- counted for, Note, i. 38 j another instance of, i. 50 — on the serum of, i. 237, Behm motion and colour of, i. 330, 6l2, Lower — on the accension of the, i. 433, Willis Blood, microscopical observ on, ii. 149, 222, Leuwenhoek — natural history of human blood, ii. 684, Boyle — component parts of, ii. 685, Note — periodical discharge of, from the finger, iii. 156 — defence of Harvey against F. Paul, iii. 195, Ent — circulation of, in the lacerta aquatica, iii. 238, Molyneux — quantity in men; celerity of circulation, iii. 417, Moulen — effect of the air on the colour of, iii. 581, Slare — experiments to ascertain the constituent parts of, iv. 283, Vieussens — remarks on Vieussen's experiments, iv. 503, . . Lancisi — on the circulation of, in tadpoles, iv. 464, Leuwenhoek — of the quantity in the human body, iv. 570 .... Lister — remarks and exp. on the circulation of, iv. 680, Cowper — observations of the circulation of, in fishes, v. 460, Leuwenhoek eels, v. 531, Same — on the force of the motion of, vii. 346, Jurin — specific gravity of human, vi. 415, Jurin — of a person dead of the plague, experiments with, vi. 585, Couzier — magnitude of the globules of vi. 660, 677 , Leuwenhoek — effect of the lungs upon, vii. 301 Nicholls — vomiting of, cured by cold drink, vii. 484, Michellotti — circulation of, through the bones, viii. 79> • • Belchier — of a white liquor separated from, ibid Stuart — circulation of, in a water-newt's tail, viii. 501, Baker — constant emission of, in coitu, viii. 620, . . Schlichting — microscopical observations of, xii. 245, Stiles — of the changes which it undergoes when extravasated into the bladder and mixed with urine, xviii. 65, Home — observ. and exper. on the colour of, xviii. 228, Wells, — See Chyle, Haemorrhage, Styptic. Blood, (injection of medicated liquors,) see Injection. Blood, (Transfusion of,) see Transfusion. Blue, Prussian, method of preparing, vii. 4, . . Woodward — first discovery of, ibid Note — observations and experiments on, vii. 6, Brown Blumenbach, John Frederick, M. D., examination of some mummies in London, xvii. 392 Bobart, Jacob, effects of severe frost on trees, &c. iii. 89 Bocone, Paulo, biographical notice of, iii. 6l3, ....Note — natural curiosities presented to R. S. ii. 1 16 Body, (Human) ©n its parenchymatous parts, i. 119, King — height of at morning and night, vii. 24, Wasse — cause of the above difference, vii. 25, Beckett — an undecayed body found in a copper mine, vii. 41, Leyel — undecayed bodies in peat moss, vii 666, Balguy — an undecayed body in a morass, ix. 364, Stovin — buried 80 years, undecayed, x. 202, Huxham and Tripe ■ more than 200 years, undecayed, xiii. 356, Huxham ( — instance of the combustibility in subjects addicted to spirituous liquors, xiii. 334, Wilmer — an undecayed body at St. Edmund's Bury, xiii. 356, Collignon — see Dissection. Boerhaave, Herman, biographical account of, v. 556, Note — chemical experiments on quicksilver, vii. 6l9> viii. 93 Bogs, of Ireland, account of, iii. 142, King — of a moving bog in Limerick, 1697, iv. 206 — another account of the same, ibid Molyneux — account of, in Ireland, v. 636, Sloane — extract from Leland respecting, v. 639 Bohemia, geological account of, ix. 688, Mounsey I Bolognian Bottles, of the breaking of, ix. 102, Bruni BON INDEX. BOOKS. 13 Bolognian bottles, exper. on similar glass, ix. 160, Allamand Bolognian stone, to prepare for phosphorescence, i. 139 — on the phosphorescence of, ii. 382 — account of the, ii. 515, Cellius — where found, and how to make shine, iv. 308, Marsigli Bolognini, disorder which caused the death of, ix. l6, Camillis Bolus Hungaricus, of the same effect as the bolns Arme- nius, i. 6 Bon, M. — , experiments on the silk of spiders, v. 542 Bonajutus, Vincent, earthquakes in Sicily, l6'92-3, iii. 602 Bonavert, Mr., of a stone at the root of the tongue, iv. 340 Bond, Henry, biographical notice of, ii. 36*1, Note — variations of the magnetic needle predicted, i. 282 — magnetical variations, and the inclinatory needle, ii. 78 Bond, John, m. n. machine for killing whales, x. 251 — of the copper springs of Wicklow, x. 366 Bones, formation and nature of, iii. 46l, Havers — - table of the dimensions of an Elephant's, v. 589, Blair — and periostaeum, microscop. observations on, vi. 484, Leuwenhoek — tinctured red by aliment, viii. 79> 83, Belchier — rendered soft by tumours, viii. 46*4, Pott — becoming flexible, case of, viii. 682 Bevan — incrusted with stone at Rome, ix. 181, Folkes — a piece extracted with a stone from the bladder, x. 270, Warner — softened and distorted, case of, x. 313, Hosty — case of the flexibility and dissolution of, x. 406, Pringle — a boney substance found in a man's pelvis, xi. 476,Brady — analytical experiments on bones, xviii. 558, . . Hatchett — see Os femoris, Os frontis, Os pubis, &c. Bones, (fossil) anelephant's found at Tonna, iv.218, Tentzel — of some extraordinary bones found at Charlton, iv. 600 — large bones found near Colchester, iv. 6'06,. . . . Luff kin — remarks on the discovery of large bones in England, iv. 637, Wallis — of an extraor. size near St. Albans, v. 671, . . Cheselden — large teeth and other bones dug up in Ireland, vi. 199. Nevill — remarks on the above-mentioned teeth,vi. 200,Molyneux — on fossil bones of elephants, vii. 240, 255, .... Sloane — of a mammoth in Siberia, viii. 155, Breyne — of a man and a deer in Yorkshire, ix. 100, Gale — tooth of an elephant found in Norfolk, ix. 111,. . Baker — found in Oxfordshire and Gloucestershire, x. 347, Same — of elephants in the isle of Sheppey, x. 489 Jacob — thigh bone ©fa large animal dug up in Oxfordshire, xi. 204, Plott — of an alligator found near Whitby, xi. 259, • • Chapman i xi. 289, . . . Wooller ■ — large teeth and bones in North America, xii. 476, 478, Collinson — observations on the same bones, xii. 504, Hunter — of large quadrupeds found in northern countries, xii.6'12, Raspe — of a quadruped found in the rock of Gibraltar, xvi. 64, Hunter — of petrified bones found at Maestricht, xvi. 151, Camper — incrusted bones found at Bayreuth, xvii. 437, Margrave of Anspach ; examination of them, 440, .... Hunter — general remarks on fossil bones, xvii. 443, Same Bones, Rev. John, particulars of a family, all of whom suf- fered under a mortification of the limbs, xi. 628 Bonet, Theophilus, biographical notice of, iii. 118, .. Note Bonnet, Charles, biographical account of, ix. 468, . . Note — observations on insects, viii. 682 Bonnet, on the vegetation of plants in moss, ix. 468 — success of inoculation at Geneva, x. 548 — earthquake at Geneva, Nov. 1755, x. 687 Bonnet, John, preternatural structure of the pudenda of a woman, vii. 42 Bonomo m. d., on worms in human bodies, v. i. Bononian stone, see Bolognian. Books, accounts and analyses of, viz. Abercromby, LuemVenereamcurandi Methodus,iii.53 — De Variatione Pulsus Observationes, iii. 169 Account of several Voyages and Discoveries, iii. 656 Allen, Nat. Hist, of the Mineral Waters of England, iv. 375 Alliot, Traite du Cancer, iv. 279 Anderson's Stereometrieal Propositions, i. 281 — Guaging Promoted, i. 352 Angelis, (Steph. de) de Infinitis Spiralibus Hyperbolis, &c. i. 268 Anthelme, Explication of the Comet of 1680-1 ii. 524 Archimedes' Arenarius, by Wallis, ii. 282 Art de Parler, ii. 308 Tailler, iii. 81 Avona, by R. S. ii. 186 B. (W.) Touchstone for Gold and Silver Wares, ii. 374 Baker's Geometrical Key, iii. 23 Baldaeus, Beschriving der Oost Indische Kusten, i. 688 Barrow, Lectiones 18 Opticae, i. 633 — Lectiones 13 Geometrical, i. 635 — Archimedes, Apollonius, Theodosius, ii. 214 Barba, on Metals, ii. 168, 174 Barneri, Predromus Sennerti, ii. 237 — Spiritus Vini sine Acido Demonstrafio, ii. 591 Bartholini, Dissertatio de Cygni Anatome, i. 381 — de Cometis 1664, 1665 Opusculum, i. 403 — Acta Medica, 8cc. Hafniensia, ii. 105, 214 — Selecta Geometrica, iK 153 — de Naturae Mirabilibus, ii. 163 — de Cadaveribus Morbosis, ii. 163 — de Peregrinatione Medica, ii. 321 — Diaphragmatis Structura Nova, ii. 360 — Specimen Philosophiae Naturalis, iv. 236 Barbette's Chirurgical and Anatomical Works, i. 722 Bathoniensium et AquisgranensiumThermarum Comp. ii. 284 Bayle Systeme General de la Philosophic, i. 412 — Dissertationes Medicae Tres, i. 523 Beccaria, De Quamplurimis Phosphoris Detectis, ix. 209 Bell, Notitia Hungariae Nova, viii. 253 Bellini, Gustus Organum, i. 135 — de Urinis, Pulsibus, &c, ii. 684 Beaufort, Cosmopoeia Divina, i. 456 Beaumont, Observations on Burnet's Theory of the Earth, iii. 580 Becher, Experimentum Chymicum Novum, i. 620 — De Morte Submersorum, v. 264 Beck (Von der) Naturalium Rerum Principia, ii. 133 Bernard, de Mensuris et Ponderibus, iii. 241 Bernard, Catal. mss. Acad. Oxon. et Cantab, iii. 653 Bernier, Empire of the Great Mogul, i. 636 Bernouilli, Ja., Treat, on the Motion of Comets, ii. 546 Beverege, Institutionum Chronolog., lib. duo., i. 351 Bianclnni, Hesperi Nova Phaenomena, vii. 359 — Experiences sur la Medecine Electrique, x. 242 Bilbery, Refractio Solis Inoccidui, &c. iv. 213 Bidloo, Anatomia Humani Corporis, iii. 260 — de Animalculis in Hepate Ovillo, iv. 499 14 BOOKS. INDEX. BOOKS. Books, accounts and analyses of, viz. Blegny on the Venereal Disease, ii. 301 Blondel, Cours d' Architecture, ii. 274- — Nouvelle Maniere de Fortifier, iii. 32 Blasius, Anatome Medulla; Spinalis, &c, i. 148 Boccone, Icones Flantarum Sicilia?, ii. 134 — Osservationi naturali, iii. 6*13 — Museo di Plante Rare della Sicilia, &c, iv. 346 — Museo di Fisica et di Esperienze, &c, iv. 351 Boerhaave, Index Plantarum Hort. Lugd. Bat., v. 556 Bohn, Epist. de Alcali et Acidi Natura, ii. 232, 591 Bohun, Origin and Properties of Wind, ii. 41 Bohadsch, Dissertatio de Utilitate Electrisationis in Morbis, x. 227 Bolnest, Way of Preparing Animals, &c. for Physical Use, i. 743 Bend, Longitude Found, ii. 36l Boneti Medicina Septentrionalis Collatitia, iii. 118 Borell, De Vi Percussionis, i. 224 — Historia Incendii /Etnei, 1669, i. 637 — De Motionibus a Gravitate dependentibus, i. 6ll — de Motu Animalium, ii. 499, 577 Borrichii, De Ortu et Progressu Chemiae Dissert, i. 279 — Hermetis Egyptiarum Sapientia, ii. 207 Bottoni, de Trinacriae Terrae Motu, vii. 46 Bourdelot, Recherches, &c, sur les Vipcres, i. 654 Bourges, Voyage de l'Eveque de Beryte par la Turquie, &c, i. 122 Boyle, Hydrostatical Paradoxes, i. 62 — Free Considerations about subordinate forms, i. 190 — Phisico-mechanical Experiments on the Air, i. 303 — Philosophical Essays and other Tracts, i. 402 — Tracts on Cosmical Qualities, i. 512 — Origo Formarum et Qualitatum, i. 543 — Tracts on Air, i. 553 — Usefulness of Experimental Philosophy, i. 603 — Origin and Virtues of Gems, i. 733 — Tracts [on several Subjects] ii. 56 — Tracts [on Effluvia, Fire, &c] ii. 91 — Tracts [Saltness of the Sea, Airs, Moisture, &c] ii. 103 — Excellency of the Mechanical Hypothesis ii. 133 — Tracts [Air, Magnets, Vacuum, Suction] ii. 183 — Considerations on the Resurrection, ii. 192 — Experiments, Notes, &c, ii. 320 — Opera Varia ii. 360 — Natural History of the Human Blood, ii. 684 — Experiments on the Porosity of Bodies, iii. 72 — Essay on the Effects of Even, and Unheeded Mo- tions, iii. 153 , — Short Memoirs of mineral waters, iii. 183 — inquiry into the Vulgar Notion of Nature, iii. 307 — Medicina Hydrostatica, iii. 437 Brahe, Tycho, Historia Ccelestis, i. 312 Branker's Edit, of Rohn's Introduction to Algebra, i. 253 Braunii Dissert, de Mercurii Congelatione, xi. 543 Breynii, Dissertatio de Polythalamiis, vii. 629 Brigg's Ophthalmographia, ii. 354 Brookhuysen, CEconomia Animalis, ii. 6l8 Browne's Travels in Hungaria, &c, ii 71 ■ ■ through part of Germany, ii. 360 Brownrigg, Art of making common Salt, ix. 518 Bullialdi ad Astronomos Monita Duo, i. 141 Buonanni, dell' Occhio e delle Chiocciole, iii. 15 Burnet, Thesaurus Medicinae Practicae, i. 31 — Telluris Theoria Sacra, ii. 515 — Archaeologiae Philosophicae, iii. 545 Books, accounts and analyses of, viz. Burrhi Epistolae duae ad Bartholinum, i. 526 BuschofFs, and Roonhuysen's, Medical Treat, ii. 300 Camelli, Tractatulus de Ambaro, v. 119 Cange, Du, Glossarium ad Scriptores Latinitatis, ii. 443 Capuani, Lezioni alia Natura delle Mofette, iii. 6l5 Cappeler, Prodromus Crystallographies, vii. 85 Cary, Palaeologia Chronica, ii. 373 Cassini, Ephemerides Mediceorum Syderum, i. 325 — Three Letters on the Sun's Motion, i. 733 — Meridiana del Tempio de S. Petronio, iv. 286 Cat, Le, Traitc des Sens, viii. 619 Catesby's Carolina, vii. 432, 577- ix. 370, 469 Cavina, Congiettura della Natura Universa, i. 538 Cellio, Fosforo overo la Pietra Bolognese, ii. 515 Celsius, Observationes pro Figura Terrae Determi- nanda, viii. 413 Chales, C. F. M. de, Cursus Mathematicus, ii. 184 Chambre, Causes of the Inundation of the Nile, i. 85 Chapuzeau, Histoire des Joyeaux, &c. i. 152 Charas, Histoire Naturelle des Animaux, Plantes, et Mineraux qui composent le Theriaque d'Androma- chus, i. 394 — Nouvelles Experiences sur la Vipere, i. 411 — Suite des Experiences sur la Vipere, i. 722 — Pharmacopee Royale, ii. 343, 431 Charlton de Causis Catameniorum, iii. 168 Charmaye, Origine des Nations, iv. 413 Chauvini Lexicon Rationale, iii. 534 Cherubin, Dioptrique Oculaire, i. 666 Cheselden, Osteographia, vii. 630 Chevalier, Description de la piece d'Ambregris, iv. 500 Chirac, de Motu Cordis, iv. 497 — Dissertatio de Incubo, iv. 498 — de Passione Iliaca, ibid Clarke's Natural History of Nitre, i. 473 Claromontius, de Aere, Solo, et Aquis Angliae, i. 703 Clos (Du) Eaux Minerales de France, ii. 300 Cluverius, Introd. inUniversam Geographiam, iv. 200 Cockburn, Diseases of Seamen, iv. 154 — Nature and Causes of Loosenesses, iv. 575 Cole, de Secretione Animali, ii. 153 Cole, de Febribus Intermittentibus, iii. 509 — de Casu Epileptico, v. 73 Commercium Epist. Collinii et Aliorum, vi. 116 Confucius, Sinarum Philosophus, iii. 393 Commelimisv Hortus Medicus Amstelodamensis,iv.228 — History of Poland, iv. 247 Connor, De Antris Lethiferis, iv. 77 Cooke's England's Improvements, ii. 266 Cordemoy, Discernement du Corps et de l'Ame, i. 1 18 — Discours Physique de la Parole, i. 268 Consentini (Cornelii) Progyranasmata Physica, i. 211 Cooke on Planting, ii. 309 Cotton's Planter's Manual, ii. 222 Cowper Myotomia Reformata, iii. 673 Craig de Lineis Rectis et Curvis, &c. iii. 332 — de Figurarum Curvilinearum Qradraturis, iii. 637 Cumberland, Essay on Jewish Weights and Measures, iii. 276 Cudworth, True System of the Universe, ii. 422 Dale, Pharmacologia, iii. 588, v. 306 Dampier, New Voyage round the World, iv. 141 Davide, Vini Rhenani Anatomia Chymica, ii. 6"2 Dary's Gauging Epitomised, i. 395 Dassier, L'Architecture Navale, ii. 395 Debes, Description of the Islands of Feroe, ii. 32 i BOOKS. INDEX. BOOKS. 15 Books, accounts and analyses of, viz. Descartes, Lettres de, i. 147 — Epistolae, pars i. & ii. i. 288 Description Anatomique d'un Cameleoa, d'un Castor, d'un Dromedaire, d'un Ours, et dune Gazelle, i. 369 Dialogue on Comets, ii. 545 Dickenson, Physica Vetus et Vera, iv. 650 Diemerbroeck, Anatome Corporis Humani, ii. 148 Diogenes Laertius, Amstelod., iii. 580 Diophanti Alexandrini Arithmeticorum, lib. sex, i. 604 Discourse on Local Motion, i. 537 Divine History of the Genesis of the World, i. 463 Dodart, Histoire des Plantes Dressees, ii. 484 Dodwell, Julii Vitalis Epitaphium, vi. 77 Dolaei, Encyclopcedia Medicinae, &c. iii. 73 D'Omerique Analysis Geometrica, iv. 442 Donati, Essay towards a Natural Hist, of the Adriatic, x. 704 Douglas, Bibliographia Anatomica, vi. 166 — Short Account of Mortifications, vii. 572 Drelincourt, Methode de Tailler la Pierre, ii. 164 — Experimenta Anatomica, iii. 140 Drope on Fruit Trees, ii. 7 Duncan, Explication des Actions Animales, ii. 444 Education, especially of Gentlemen, ii. 283 Egede, Natural History of Greenland, viii. 722 Elsholt, Clysmatica Nova, i. 442 — Curious Distillatory, ii. 412 English Atlas, vol. i., ii. 501 Entii Antidiatriba, seu de Respirationis Usu, ii. 471 — Apologia pro Circuitione Sanguinis, iii. 195 Ephemeridum Medico-Physic. Germanise, ii. 127, 353 Epistola ad r. s. de Nuperis Terrae Motibus, iii. 581 Etmuller, Opera Theoretica et Practica, iii. 209 Evelyn, Translation of Cambray on Painting, i. 280 — Sylva et Pomona, i. 404 — Navigation and Commerce, ii. 134 — Philosophical Discourse of Earth, ii. 245 — Numismata, a Discourse of Medals, &c. iv. 235 Euclidis Elementa Geometrica novo Ordine Demons- trata, i. 89 Eygel, Apologema pro Urinis Humanis, ii. 1 19 Fabretti de Aquis et Aquaeductibus Romae, iii, 5 Fabri, H., Tract, duo, de Plantis, de Animalibus, de Homine, i, 122 — Synopsis Optica, i. 224 — — — — • — Geometrica, i. 553 — Dialogi Physici, ibid — Physica in Decern Tractatus Distributa, i. 563 Fairfax, Bulk and Salvage of the World, ii. 119 Fehr, de Absynthio Analecta, i. 622 Felibien, sur les Vies et Ouvrages des Peintres, i. 143 Fergusons's Labyrinthus Algebrae, i. 373 Fiorentino, osservationi alle Torpedini, ii. 485 Flamsteed, Historia Ccelestis Britannica, vii. 101 Font, Charles De la, Dissert, de Veneno Pestilenti, i. 612 Fortrey, England's Interest and Improvement, ii. 127 Foucquet, Chinese Chronological table, vii. 427 Fourneillis, Vindication of Descartes' System, i. 490 Fourmont, Reflections sur les Anciens Peuples, &c. viii. 389 Francisci, Elementa Geometriae planas, i. 553 Franklin, Experts, and Observ. on Electricity, x. 189 Fratta, Practica Minerale, ii. 517 Freind, Praelectiones Chemicae Oxoniae, v. 490, 647 French Gardiner and English Vineyard, ii. 309 Frisii De Figura et Magnitudine Telluris, x. 305 Books, accounts and analyses of, viz. Fryers Nine Years Travel in East India and Persia, iv. 310 Gales' Original of Human Literature, i. 6l9 Gansii Coralliorum Historia, i. 443 Gaveti, Nova Febris Idaea, iv. 606 Gentleman's Recreation, ii. 247 Gent's whole Art of Husbandry, ii. 214 — Systema Horticulturae, ii. 412 Germani, Homo ex Ovo, ii. 6 Gersten, Tentamina Systematis ad Mutationes Baromet. vii. 592 Glaser, New Treatise of Chemistry, ii. 395 Glissonii Tractatus de Ventriculo, &c. ii. 343 Gmelin, Flora Siberica, ix, 491, x. 351 Goodall, College of Physicians Vindicated, ii, 267 Gordon's Geographical Grammar, iv. 428 Graba, Elaphographia, i. 281 Graaf, R. de, De Succo Pancreatico, i. 62, 674 — Epistola de Partibus Genitalibus, i. 241 — De Virorum Organis Generation! Inservientibu9, i. 711 Graevii, Julius Celsus de Rebus Gestis Julii Caes. iv. 113 Grand, (Le) Philosophia Veterum, i. 587 Grande, Le, Carentia Sensus et Cognitionis in Brutis, ii. 203 — Institutio Philosophia?, i. 69O — Historia Naturae, ii. 72 Greenhill, Art of embalming, v. 247 Gregory, Vera Circuli et Hyperbolae Quadrature, i. 232 — Geometriae Pars universalis, &c. 1. 251 — De Dimensione Figurarum, iii. 79 — Catoptricae et Dioptricae Elementa, iv. 77 — Astronomiae Physicaeet Geometricae Elementa, v. 10 — Euclidis quae supersunt Omnia, v. 104 Grew, Anatomy of Vegetables, i. 660 3 ii. 655 — Idea of a Phytological History, ii 103 — Compara. Anatomy of the Trunks of Plants, ii. 255 — De Sal is Cathart. in aquis Ebshamensibus, iv. 31 Grube de modo simplicium medicamentorum facultates cognoscendi, i. 464 Grimaldi, Physico Mathesis de Lumine, i. 675 Guarrini, Placita Philosophica, i. 135 Guedron, Recherches sur la Nature, &c. des Cancers, iv. 470 Guericke, Experimenta Nova de Vacuo Spatio, ii. 29 H. M., Enchiridion Metaphysicum, i. 604 Hales' Primitive Origination of Mankind, ii. 411 — Vegetable Statics, vii. 188 Haller, Enumeratio Stirpium Helvetia, vii. 513, viii. 65, Note Halley, Catal. Stellarum Australium, ii. 446 — Astronomiae Cometicae Synopsis, v. 201 — Translation of Apollonius, vi. 327 Hamel (du) de Corporum AfFectionibus, i. 536 — de Mente Humana, ii. 13 — -De Corpore Animato, ii. 115 — De Consensu Veteris et Novae Philosophiae, ii. 283 Harris, Dictionary of Arts and Sciences, v. 149 Hartmann, Hist. Figurarum Embryonum, 4 Septima- narura, iv. 236 Havers, Osteologia Nova, iii. 46l Hayne's Prevention of Poverty, ii 193 Hecatoste, Observationes Physico- Medicae, ii. 321 Heidel, Trithemii Steganographia Vindicata, ii. 388 Helvetii, Cogitationes de Natura Visionis, i. 597 Henepin, Description de la Louisiane, iii. 153 16 BOOKS. INDEX. BOOKS. Books, accounts and analyses of, viz. Henshaw, Aero Chalinos, ii. 379 Hermans, Paradisus Batavus, iv. 352 Hertodt, Crocologia, i. 622 Hevelii Descriptio Cometae, 1665, i. 115 — Cometographia, i. 288 — Machina Coelestis, ii. 1 19 — Annus Climactericus, iii. 216 Highmore, De Hysterica et Hypoch. Passione, i. 410 Hippocratis Aphorismi cum Listeri Comment, v. 37 Hire, (de la) Nouvelle Methode en Geometrie, ii. 353 — Tabulae Astronomicae, iii. 419 Historia de Ethiopea a Alta, i. 3fj0 History of the Church of Malabar, iii. 638 Hobbes de Principiis et Ratiocinatione Geometrarum, i. 85; Animadversions upon it, by Dr. Wallis, i. 107 — Rosetum Geometricum, i. 605 — Principia et Problemata Geometrica, ii. 103 — Decamaron Physiologicum, ii. 431 Hobokeni Anatomia Secundinae Humanae, i. 442 Hoffmann de Cinnabari Antimonii, iii. 231 Holder, Elements of Speech, i. 352 — Treatise on the Principles of Harmony, iii. 624 Hook, on the Earth's Motion, ii. 126 Hook, Description of Helioscopes, ii. 237 — Lectures and Collections, ii. 437 — Animadversions on the Machina Caelestis of Heve- lius, ii. 174 Home (J. Van) de Partibus Genitalibus in utroque Sexu, i. 241 Horrocii Opera Posthuma, ii. 12 Hodges on the Plague of London, 1665, i. 702 Hortus Indicus Malabaricus, ii. 590, iii. 518, 540, 686 Hughes's American Physician, i. 722 Huret, Optique de Portraiture et Peinture, ii. 6 Haxham, de Aere et Morbis Epidemicis, viii. 264 Huygens, Horologium Oscillatoriura, ii. 79 — Astroscopia Compendiaria, ii. 64 — Celestial World discovered, iv. 429 I. M. Whole Art of Husbandry, v. 362 Isernc, Nouvelle Science des Temps, ii. 369 Jessop, Propositiones Hydrostaticae, iii. 418 Josselin's New England's Rarities Discovered, i. 743 Jurin, De Vi Motrice, viii. 46l Keill on Animal Secretion, v. 49 Kennet, Parochial Antiquities, iv. 92 Kerckringii Spicelegium Anatomicum, i. 413 — Anthropogeniae Ichnographia, i. 585 — Comment, in Currum Triumphalem Antimonii, Valentini, i. 596 Kersseboom, on the Population of Holland, &c, viii. 253, 628 Kersey's Elements of Algebra, ii. 81 Kessel (Van) Pharmacopoeia Harlemensis, iv. 504 Klein, Historia Piscium Naturalis, viii. 551 Klobii, Historia Ambrae, i. 193 Kircheri, China Illustrata, i. 169 — Ars Magna Sciendi, sive Combinatoria, L 412 Kunkel's Chemical Touchstone, iii. 125 Labbe, Abrege de l'Histoire Sacree et Prophane, i. 382 Lachmund, Descriptio Fossilium Hildesheimensi, i. 655 Lambeci lib. i. Prodromi Hist. Literarias, i. 211 Lana, Prodromo overo Saggio, &c. i. 574 Launay, Les Essays Physiques du Sieur de, i. 211 "Laurens, Specimina Mathematica Francisci Du, i. 211 Lecomte, Memoires de la Chine, iv. 175 Legati, Museo Cospiano, &c. ii. 442 Books, accounts and analyses of, viz. Lemery's Course of Chemistry, iii. 221 Leowardiae, Cartesius Mosaizans, i. 456 Leyser, Observationes Medicae, i. 381 Leibnitz, Theoria Motus Concreti et Abstracti, i. 6l3 Leigh, Phthisiologia Lancastriensis, iii. 602 Lewis, Essay on Education, ii. 186 L'Estrange, Discourse of the Fishery, ii. 128 Linck, Commentatio de Cobalto, vii. 171 Lhwid, Archaeologia Britannica, v. 372 281 Lister, Tractatus de Araneis et Cochleis, ii. 436 — Gcedartius on Insects, ii. 560, iii. 106 — de Fontibus Medicatis Angliae, ii. 577, iii. 32 — Exercitatio Anatomica de Cochleis, &c. iii. 624 — Apicii Ccelii de Opsoniis et Condimentis, v. 175 Logica, sive Ars Cogitandi, ii. 154 Logarithmic solar Tables, xi. 507 Lower, De Corde j De Motu et Colore Sanguinis, i. 330, 612 — de Catarrhis, i. 6l2, 655 Lubienietz, Theatrum Cometicum, i. 254 Ludovici Dissertationes de Pharmacia Moderna, i. 647 Lux Mathematica, ii. 6 Maclaurin, Geometria Organica, vi. 464 — Treatise on Fluxions, viii. 632, 667 Mairan, Traite de l'Aurore Boreale, vii. 637 Major, de Lacte Lunne Dissertatio Medica, i. 464 Malpighii Dissert, de Formatione Pulli in Ovo, ii. 13 — Anatome Plantarum, ii. 229, 483 — Opera Posthuma, iv. 168 — Dissertatio Epistolica de Bombyce, i. 367 — De Viscerum Structural, i. 322 Mappi, Catal. Plantarum Horti Argentinensis, iii. 534 Marchetti Exercitationes Mechanicae, i. 472 — de Resistentia Solidorum, i. 710 Marii Castorologia, a Franco, iii. 244 Marriotte, Traite de la Percussion, ii. 388 — Traite du Mouvement des Corps fluides, iii. 308 Marsigli, Dissert, del Fosforo, della Pietra Bolognese, iv. 307 — Danubialis Operis Prodomus, iv. 640 — de Generatione Fungorum, vi. 195 Martyn, Historia Plantarum Rariorum, vii. 321 — on Teaching the Latin Tongue by use alone, i. 36 1 Mayow, De Respiratione, et De Rachitide, i. 295 — - Tractatus Quinque Physico Medici, ii. 142 Mead on Poisons, v. 16 Meibomius, de Cerevisiis, Potibusque, &c. i. 575 — de Fabrica Triremium, i. 6*77 Mengoli, Musica Speculativa, ii. 125 Mercator, Logarithmotechnia, i. 2?2 — Institutions Astronomicae, ii. 299 Memoires pour L'Hist. Nat. des Animaux, ii. 2S9 translated, iii. 390 Merret, Pinax Rerum Naturalium Brittan. i. 135 Messange, Probl. de la Quadrature du Cercle, iii. 345 Mindereri Medicina Militaris, ii. 127 Miscellanea Curiosa Medico-Physica, &c. i. 56l, 713 Molinetti Dissertationes Anatomicae, i. 554 Moncaeius de Divinatrice et Operatrice, iii. 73 Moore's Modern Fortification, ii. 80 More, Remarks on two late Treatises, ii. 275 Moreland, Descrip. of 2 Arithmetic Instruments, ii. 71 Morellius, Specimen Universae Rei Nummariae An- tiqua, iii. 106 Morrison, Praeludia Botanica, i. 341, ii. 214 — de Plantis Umbelliferis, i. 702 BOOKS. INDEX. BOOKS. 17 Books, accounts and analyses of, viz. Morton nvetroXoyix, seu de Morbis Acutis, iii. 534 Moxon's Mechanic Excercises, ii. 431 Muller, Africanische Landschaft Fetu, ii. 168 — Proposals for a History of Russia, vii. 6l8 Muller, Treatise of Conic Sections and Fluxions, viii. 145 Mullerus, De Rebus Sinicis, ii. 412 Munting, Waare Oeffeningder Planten, ii. 192 Musgrave, de Arthritide, v. 135 — Julii Vitalis Epitaphium, vi. 77 — Geta Britannicus, v. 202 — Dissertatio de Dea Salute, vi. 264 Mutoli, Del Movimento della Cometa 1664, i. 403 Natural History of Cochineal, vii. 388 Needham, Disquis. Anatom. de formato fcetu, i. 177 Newton's Principia Mathematica, iii. 358 — Method of Fluxions by Colson, viii. 88 Nollet, Letters concerning Electricity, x. 372, xi. 580 Nouveaux Elemens de Geometrie, i. 224 Norwood's Seaman's Practice, xi. 593 Nuck, de Ductu Salivali Novo, &c. iii. 241 Nuland Elementa Physica, i. 536 Observations sur un Grand Poisson et un Lion, i. 191 Observations touching the Torricellian Expert, ii. 134 on the Dublin Bills of Mortality, ii. 560 Olhoff, Excerpta ex Literis ad Hevelium, ii. 658 Origin of Forms and Qualities illustrated by Experi- ments, i. 65 Pacchionus, de Gland. Durae Meningis Humanae, v.6l8 Paisley (Lord) Attractive Virtue of Loadstones, viii. 383 Papin's Continuation of the Bone-Digester, iii. 373 — Recueil de Nouvelles Machines, iv. 154 Pardies, Elemens de Geometrie, i. 674 — Discours de la Connoissance des Betes, i 71 1 — Machines pour les Quadrans, ii. 42 — Statique, ou Science de Forces Mouvantes, ii. 70 Parsons, on the Nature of Hermaphrodites, viii. 477 Pauli Quadripartitum Botanicum, i. 647 Pechlinius, de Aeris defectu, et Vita sub Aquis, ii. 321 — Theophilus Bibaculus, iii. 119 Perrault, L' Architecture de Vitruve, ii. 202 — & Marriotte, Letters on Vision, ii. 644 Petit, Sur la Nature du Froid et du Chaud, i. 666 Petiver, Gazophylacium Naturae et Artis, v. 49, 647 Petiveriani Musei Centuria prima, iv. 132 Pettus, Fleta Minor, ii. 618 Petty, on the Use of Duplicate Proportion, ii. 172 Peyer, Merycologia, sive de Ruminantibus, iii. 243 Pflugk, de Bibliotheca Budense, iv. 307 Pharmacopoeia Collegii Regalis Lond. ii. 378 Philosophical Essay on Music, ii. 379 Physic, Discourse concerning, and abuses thereof, i. 298 Picard and De la Hire, Map of France, iv. 142 Pitcairn, Dissertatio De Febribus, iv. 46 Piatt's Garden of Eden, ii. 210 Plott, Natural History of Oxfordshire, ii. 394 — De Origine Fontium, iii. 1 16 Natural History of Staffordshire, iii. 336 Plukenet, Almagestum Botanicum, iv, 141 Pococke, Philosophus Autodidactus, i. 6l3 Polenus, de Motu Aquae mixto, vi. 324 Potter, Lycophronis Alexandra, iv. l6l Prestet, Elemens de Mathematiques, ii. 307 Prose di Sigriori Academico di Bologna, ii. 34 Pulmonum, Specimen Novae Hypoth. de motu, i. 588 Rae, de, Clavis Philosophise Naturalis, ii. 369 Ramazzini De Fontibus Mutinensibus, iv. 213 Books, account and analyses of, viz. Ray, Catalogus Plantarum Angliae, i. 513, ii. 378 — Journey thro' the Low Countries, Germ., &c, ii. 50 — Historia Plantarum, iii. 357 — Wisdom of God manifested, iii. 492 — Physico-theological Discourses, ibid — Collection of Voyages and Travels, iii. 543 — Synopsis Animalium Quadrupedum, iii. 565 Redi, Esperienze intorno alia gener. degl' Insetti, i. 429 — sopra alcune Oppositioni alle Sue Observation! In- torno alle Vipere, i. 544 — Esperienze intorno a diverse cose naturali, ii. 58 Relat. de Ritrovamento dell' Uova de Chiocciole, ii. 667 Reverhorst, de Motu Bilis, iv. 503 Reynel, True English Interest, ii. 132 Rhyne, Tractatus, ii. 631 Ricci (Mic. Ang.) Exercitatio Geometrica, i. 269 Riccioli, Astronomia Reformata, i. 148 Ridley, Anatomy of the Brain, iv. 13 Robins, New Principles of Gunnery, viii. 677 Rohault, Traitc de Physique, i. 587 Rose's English Vineyard vindicated, i. 89. Rosetti Dimostratione Delle Sette Propositione, i. 538 — Treatise on the Comet, 168O-I, ii. 524 Rudbeckii Atlantica sive Manheim, ii. 525, v. 239, 240 Ruysch, Adversariorum Anatom. Med., vi. 676 Saggi di Naturali Esperienze, i. 231 Salmon, Essay on Music, i. 231 Salmon, Pharmacopaeia Bateana, iii. 601 Salmasii Praef. in lib. De Homonymis Hyles Iatricae, i. 343 Salnove, La Venerie Royale, i. 269 Sammes, Britannia Antiqua Illustrata, ii. 292 Sanguineti Dissertationes latrophysicae, iv. 606 Sanctorii Medicina Statica, ii. 412 cum Comment. Lister, iv. 576 Schaeffer, Icones et Descriptio Fungorum, xi. 6l5 Scheuchzer, Lithographia Helvetica, v. 136 Schefferi Lapponia, ii. 132 Scilla, circa i Corpi Marini che Petrificati, iv. 66 Seneschall de AnnoMense et die ChristiNati, &c. i. 464 Sengwerdius, de Tarantuld, i. 241 Sharrock, Propagation andimprov. of Vegetables, i. 734 Sheldron's Ptolemaei Harmonica, ii. 559 Sherburne's Sphere of Manilius, a poem, ii. 185 Sheringham, De Anglorum Gentis Origine, i. 489 Sherley, on the Probable Origin of Stones, i. 702 Sherley, on Scurvy-grass, ii. 300 Sibbald, Scotia Illustrata, iii. 98 — Phalcenologia Nova, iii. 599 Siller, Antiquities of Palmyra, or Tadmor, iv. 212 Simpson's Philosophical Dialogues, ii. 395 Sinclar, Ars Gravitatis et Levitatis, i. 380 Sloane, Catal. Plantarum Insulae Jamaicae, iv. 103 — Voyage to Madeira, Barbadoes, v. &c. 371 Slusii, R. F. Mesolabum, i. 327 Smith, England's Improvement Revived, ii. 132 ■ Essay on, ii. 133 Somner, Treatise on the Roman Forts and Ports in Kent, iii. 521 Spon, Recherches Curieuses, ii. 677 Spratt's History of the Royal Society, i. 177 Springsfeld, deThermis Carolinis in Dissolvendo Cat- culo, xi. 56. Smith's, King Solomon's Portraiture of Old Age, i. 86 — ■ • Edition of Cotes' Harmonia Mensurarum, vi. 587 Steenvelt, Dissertatio de Ulcere Verminoso, iv. 4>j% 38 BOOKS. INDEX. BOS Book*, account and analyses of, viz. Stevenson's Mathematical Companion, ii. 135 — Royal Almanack, ii. 169, 257, 36*1 Steno (Nicolai) de Musculis et Glandulis Observ. i. 62 — Musculi Descriptio Geometrica, i. 225 — Dissertation on a Solid in a Solid, i. 605 Strauchii, yEgidii, Breviarium Chronologicum, i. 381 Sturmii Collegium Experimentale sive Curiosum, ii. 265 1 — Epistola de Magnetica Variatione, ii. 56l — Collegium Experimentale, ii. 221 Swammerdam, de Respiratione etUsu Pulmonum, i. 1$0 — Historia Generalis Insectorum, i. 523 — Uteri Muliebris Fabrica, i. 733 Sydenham, Methoduscurandi Febres, i. 69 — Observationes Medicae, ii. 283 — de Podagra et Hydrope, ii. 658 Sylvatici Institutio Medica, i. 647 Sylvius, F. de le Boe, Praxeos Medicae Idea Nova, i. 289, 595 — De Affectu Epidemico Ann. 1669, Leidae, i. 6l3 Sympson's Chemical Anatomy of the Scarborough Wa- ters, i. 303 j his vindication of it, 4^0 — Zymologia Chymica, ii. 232 Systeraa Bibliothecae Col. Paris, Soc. Jes. ii. 442 Tabula Numerorum Quadratorum decies millium, i. 71 1 Tackenii, Ottonis, Hippocrates Chymicus, i. 381 Tacquet Opera Mathematics, i. 314 Tavernier, Voyages through Turkey, Persia, &c. ii. 423 Taylor, Linear Perspective, vi. 172 — Methodus Incrementorum, vi. 189 Tennison's Examination of the Creed of Hobbes, i. 526 Thesaurus Rerum Naturalium, &c. vii. 667 Thevenot, Several curious Voyages, i. 85, ii. 34 Thoresby, Topography of Leeds, vi. 174 Thurston, De Respirationis Usu Primario, i. 420 Tillingius, De. Laudano Opiato, i. 622 Tonstal, Scarborough Spa Anatomized, i. 7^3 Tournefort, Histoire des Plantes, &c. iv. 322 Traite des Moyens a rendre les Rivieres Navigables, iii. 581 Trapham, Account of Jamaica, ii. 446 Travigini Disquisitio Physica Terrae Motuum, i. 463 Trew, on the differences of the body before and after birth, viii. 425 Trichiasis admodum Rara, iii. 156 Trumphii Scrutinium Chymicum Vitrioli, i. 289 Tuhhfat Ilkibar, printed at Constantinople, vii. 556 Tyson, Phocaena, Anatomy of a Porpus, ii. 500 — Orang Outang, sive Homo Sylvestris, iv. 431 Valsalva, Tractatus de Aure Humana, v. 220 Vareni, Geographia Generalis, ii. 50 Vanslebio, Relatione dello Stato dell' Egypto, i. 595 Verney, Traite de l'Organe de l'Ouie, ii. 643 Veussens, Raymond, Neurographia Universalis, iii. 210 Viviani, De Locis Solidis, v. 137 Voightii Deliciae Physicae, i. 656 Volckamer, Flora Noribergensis, iv. 514 Vossius, De Nili et Aliorum FluminumOrigine,i. 117 — De Poematum Cantii et Viribus Rythmi, ii. 62 Voyage de Si am des Peres Jesuites, iii. 345 Voyages and Discoveries in South America, iv. 278 W. (J) Vinetum Britannicum, ii. 284 Wagneri Historia Naturalis Helvetia;, ii. 645 Wallace's Account of the Orkney Islands, iv. 487 Wallis, Confutation of Hobbes on the Quadrature of the Circle, i. 359 — second editipn, enlarged, i. 417 Books, account and analyses of, viz, Wallis, De Motu Tract. Geomet., i. 410, 471, 646 — Binae Methodi Tangentium Epitome, i. 695 — Exercitationes Tres, ii. 435 — Treatise of Algebra, iii. 194 — his Mathematical Works, iv. 29, 410 Webb's Historical Essay on the Language of China i. 360 Webster's History of Metals, i. 543 Wedelius, de Sale Volatili Plantarum, ii. 124 Weidleri Observationes Meteorological, &c. vii. 384 — Commentatio de Parheliis, 173o, viii. 433 — Dissertation on Numeral Figures, ix. 46 Welchii Basis Botanica, iv. 307 Wilkins, on a Real Character, and a Philosophical language, i. 254 Willis, Hysterica; et Hypocondriacae Pathologia Vindi. cata, i. 432 — De Anima Brutorum, ii. 722 — Pharmaceutice Rationalis, ii. 118, 265 Willius de Morbis Castrensibus Internis, ii, 412 Willughbii, Ornithologia, ii. 252 — Historia Pisciura, edit, a Raio, iii. 257 Witsen Scheeps Bouw en Bestier, i. 651 Wittie, on Sympson's Hydrologia Chymica, i. 374 Woodward, Natural History of the Earth, iv. 41 Wotton's Reflections on Ancient and Modern Learn- ing, iii. 678 Yarranton, England's Improvements, ii. 369 Zimmermanni Cometo-scopia, ii. 646 Zwelfer's Pharmacopaeia Regia, i. 432 Borametz, see Agnus Scythicus. Borassaw, M., of the falls at Niagara, vi. 574 Borax, on the production of, xvi. 282, Blane xvi. 284, Rovato — decomposition of the acid of, xviii. 457, Crell Borelli, J. Alph. biographical notice of, i. 224 Note — on the doctrine of percussion, i. 225 Borlase, Rev. Wm., biographical notice of, ix. 699, Note — of the sparry productions of Cornwall, ibid. — alteration in the number and extent of the Scilly Isles, x. 324 — effects of a thunder storm in Cornwall, x. 335 — agitation of the waters in Cornwall, 1755, x. 653 — subterraneous trees in Cornwall, xi. 80 ■ — earthquake in Cornwall, 1757> xi. 196 — antiquities found in Cornwall, xi. 322 — agitation of the waters in Mount's-bay and elsewhere, March, 1761, xi. 601 j July, 1761, xi. 621 — violent thunder storms in Cornwall, xi. 622 — mildness of the winter of 1 762, in Cornwall, xi. 684 — fall of rain in Cornwall, 1762, xi. 685 at Mount's-bay, and state of the weather, xii. 99 — specimens of native tin found in Cornwall, xii. 277, 359, 597 — fall of rain at Bridgwater, and at Mount's-bay, 1769, xiii. 46 Mount's-bay, 1770, xiii. 126 __ 1771, xiii. 325 Borrichius, Olaus, biographical account of, i. 279* • • Note — of his experiment of chemical accension, ii. 653, Slare Boscovich, Roger Jos., biograph. account of, xi. 500, Note — prognostication of a transit of Venus, ibid. — of a new micrometer and megameter, xiv. 248 Bose, Geo. Matth., electrical phaenomena, ix. 12? BOY INDtfX. BRE 19 Bose, Geo. Matth., electricity of glass which has been strongly heated, ix. 681 — lunar eclipse, June, 1750, x. 94 — account of the vegetable byssus, x. 425 Botany, on the early cultivation of, in England, xiii. 383 — See Plants. Bourbon, Count de, analytical description of the crystalline forms of Corundum, xviii. 368 Bourdilot, Abbe, biographical notice of, i. 654 Note — on the poison of vipers, i. 654 Bourzes, F., luminousness of the water in the Indian seas, vi. 53 Bourgignon, M., new volcanic island near Santerini, v. 446 Boulimia, see Appetite. Boutan, vegetable and mineral productions of, xvi. 539, Saunders — diseases of, xvi. 549, Same Bovey Coal, see Coal, Bowditch, Samuel, of a woman living six days under now, vi. 69 Bowels, instance of inverted bowels, ii. 154, .... Sampson — case of transposition of the viscera, xvi. 483, .... Baillie — uncommon formation of the viscera, xvii. 295, Abernethy Bower, Thomas, m. d., tumour in the cheek, vi. 319 Bowles, Wm., geological remarks on the North of Spain, xii. 340 — formation of the emery stone, xii. 341 Box, observations on the pores of the leaves of, vi. 541, Leuwenhoek Box Hill, when first planted, xii. 595, Note Boy, a gigantic boy with extraord. genitals, ix. 95, Almond Boyle, Hon. Robt, some account of, i. 4 Note — his experimental history of cold, i. 4. 17 — account of a monstrous calf, i. 5. — a monstrous head with eyes united, i. 29 - — account of an earthquake near Oxford, i. 60 — directions for making observns. with the Barometer, i 62 — heads for the natural history of a country, i. 63 — account of a book on the origin of forms and qualities, i. 65 — preserving birds taken from the egg, i. 66 — on a new statical baroscope, i. 77 •— experiments for suddenly producing a great degree of cold, i. 86 j method of cooling liquors, i. 87 — inquiries concerning the sea, and sea-water, i. 119 mines, i. 123 — Dr. Lower's method of transfusion of blood, i. 128 — trials of transfusion of blood proposed, i. 143 — experiments of injecting liquors into blood, i. 201 . ■ - withdrawing air from shining wood and fish, i. 211 — comparison of burning coal and shining wood, i. 215 — weight of water in water with common balances, i. 374 — new pneumatical experiments, i. 473 j continued 490 — observations on shining flesh, ii, 31 — effect of a varying atmosphere on bodies in water, ii. 42 — nature of ambergris, ii. 94 — account of Van Helmont's laudanum, ii. 155 — experiment on the dilatation of fish, in water, ii. 212 — new essay instrument, ii. 214 — experiments on air, ii. 246 — superficial figures of contiguous fluids, ii. 362 — same experts, continued, particularly of water, ii. 370 — a newly invented lamp, ii. 498 — account of a self-moving liquor, iii. 222 — his discovery of phosphorus, iii. 478, and Note — way to ascertain the degree of saltness in waters, iii. 496 Boylston, m. n., of ambergris found in whales, vii. 57 Bozes, Claude Gros de, on the medals of Pescennius Niger, x. 50 Tetricus, x. 349 Bradley, Richard, experiments on the motion of sap, vi. 254 — vegetation of mouldiness on a melon, vi. 257 Bradley, James, d. d., biographical account of, vii. 13. Note — observation of the comet of 1723, vii. 13 j of 1737, viii. 149; of 1757, xi. 169 — longitude of Lisbon, vii. 141 — apparent motion of the fixed stars, vii. 308 j ix. 417 — observations with isochronal pendulums, vii. 649 — directions for using the common micrometer, xiii. 277 — calculations of the latitude of Greenwich, xvi. 224 Bradley, John, Venus occulted by the moon, x. 188 Brady, Samuel, of a puppy alive in the matrix without a mouth, v. 276 Brady, Terence, m. d., description of some polype insects, x. 617 — a bone found in a man's pelvis, xi. 476 Brahe, Tycho, biography of, i. 312 j remarkable supersti- tion, 313 — account of his observatory, iv. 525, Gordon j v. 46, Oliver Braikenridge, Rev.W., a method of describing curves, viii. 5 — population within the London bills of mortality, 1704 to 1753, x. 535 — on a table of the probabilities of life, x. 598 — method of enumerating the population of England, x. 621 j xi. 186 — increase of the population of Britain and Ireland, xi. 51 — on the sections of a solid, xi. 425 Brain, observations on the brain, i. 171, 323, . . Malpighi — pathology of the brain and nerves, i. 214, . . ♦ . . . Willis — discourse on the anatomy of, i. 387> Steno — microscopical observations on, ii. 150, 402; iii. 122, Leuwenhoek — a petrified glandula pinealis, iii. 340, King — of a child born alive without a brain, iv. 149, . . Preston ————— depressed into the hollow of the vertebrae, iv. 1 64, Tyson — one hemisphere sphacelated, and a stone in it, iv. 165, Same — of a child born without, iv. 373, Bussiere, — see Dura Mater, Epilepsy. Bramins, religion, notions, manners, &c. of, iv. 534, Marshal Bramin's observatory, see Observatory. Brander, Gustavus, description of belemnites, x. 542 ' — remarkable echinus at the Isle of Bourbon, x. 628 — effects of lightning on a church, x. 629 Brandy, how to prove it French, vii. 120, .... Newman Brass, transmutation of copper into, iii. 535, . . . Povey — on giving magnetism and polarity to, xi. 985, . . Arderon — on the magnetic properties of, xvi. 57, 170, . . Cavallo xvii. 145, Bennet Brass wire, bad effects on the hands from cleansing, xi. 510, More Brattle, T., solar and lunar eclipses at New England, v. 148 — lunar eclipse, New England, 1707, v. 379 Brown, Prof, exper. on the congelation of mercury, xi. 544 Brazil, of the Pharaos lice at, ii. 434, Guattini Bread, from turnips, method of making, iii. 599, . . Dale Bread-fruit tree, description of the, xiv. 572, . . Thunberg Breast, a gibbosity of the sternum, ix. 649, Huber Breasts, excessive swelling of a woman's, i. 393, 402, 405, Durston Breath, observ. on shortness of, iv. 671, Leuwenhoek C2 20 BRO INDEX. BUL Breathing, see Respiration. Breintnall, Joseph, meteors seen at Philadelphia, viii. 409 — effects of the bite of a rattle- snake, ix. 229 Bremond, M. De, magnetism communicated by lightning, viii. 463 Brereton, O. S., accident by lightning at East-Bourn, xv. 21 Breslaw, population of the city of, iii. 483 Brewer, Jas., m. d ., of a bed of oyster-shells in Berkshire, iv. 4?1 Breyne, Joh. Phil., plants and insects of Spain, v. 239 — account of a journey through Italy, v. 675 — the agnus Scythicus, vii. 103 — of a leaf lodged in a piece of amber, vii. 160 — account of the coccus Polonicus, vii. 511 1 radicum, vii. 574 — Mammoth's bones dug up in Siberia, viii. 155 — ill effect of earthy absorbents on the kidneys, viii. 452 Brice, Alex, observ. of a comet, 1766, xii. 287 — method of measuring the velocity of wind, xii. 338 — to ascertain the quantity of water in a fall of snow, xii. 339 Bricks, method of making in England, viii. 482, .... Note Bride Kirk, see Inscriptions. Bridewell, at Norwich, description of the ancient building, ix. 167, .Baker Bridge, of St. Esprit in France, description of, iii. 43, Robinson — other bridges compared with the above, iii. 74, . . Same — description of one 70 feet long without a pillar, . . ibid Bridgman, Orlando, storm of thunder, &c, v. 431 Bridgnorth, bill of mortality, ancient tumuli, &c, viii. 581 Stackhouse Briggs, Wm., D. r>., new theory of vision, ii. 540, 6ll — two cases of extraordinary vision, iii. 33, 9.9 — cause of blindness coming on at dusk, iii. 9.9 — case of jaundice affecting the sight, iii. 652 Bright, Mr., the fat man of Essex, account of, x. 184, Cole Brimstone-hill, at Guadaloupe, descrip. of, x. 700, Peyssonel Brine, on the formation of salt and sand from, vi. 589, Plott Bristle, lodged in a man's foot, effect of, ix. 244, . . Arderon Bristol, population of, 1741 — 50, x. 379> Browning — heat of the waters, xii. 419, Howard ■ — — xii. 420, Canton Britain, on the ancient history of, ii. 292. ....... Sammes — if formerly a peninsula, vi. 293, Musgrave Brocklesby, R., m. d., biographical account of, ix. 3l6, Note — experiments with the Indian poison, ibid — on the power of hearing in fishes, ix. 484 — of a poisonous root found among gentian, ix. 488 — on the irritability of animal fibres, x. 613 Brodie, James, foetus voided by the ulcerated navel, iv. 173 Bromfield, Wm., biographical notice of, viii. 488, . . Note — foetus nine years in the abdomen, ibid Bronchocele, remarks on the, iv. 506, Silvestre Bronchotome, account of an operation of, vii. 438, . . Martyn Brontiae and ombriae, description of, iii. 543, Lister Brook, Abraham, of a new electrometer, xv. 308 — description of his mercurial gage, xv. 702, Note Brooke, Richard, m. p., methods of inoculating, x. 268 — diaries of the weather in Maryland, xi. 333 Brothai, F., curiosities in Upper Egypt, i. 591 Brotherton, T., experiments on the growth of trees, iii. 363 Brougham, Henry, experts, and observ. on the inflection, reflection, and colours of light, xvii. 725, xviii. 196 — porisms in the higher geometry, xviii. 345 Broughton, in Lincolnshire, account of, iv. 521, De la Pryme Brouncker, Lord, biographical account of, i. 233, Note Brouncker, Lord, on the squaring of the hyperbola, ibid — synchronism of vibrations of a cycloid, ii. 64 — on a right line equal to a curve, ii. 113 Broussonnet, P. M. Aug., description of the ophidium bar- batum, xv. 134 Brown, Edw., m. r>., biographical notice of, i, 436 — two parhelia seen in Hungary, i. 349 — on damps of mines in Hungary, 356 — on the quicksilver mines in Friuli, i. 407 — account of the lake of Zirchnitz, i. 409, ii- 170 -— on the mines, baths, &c. of Hungary, Transylvania, and Austria, L 436 — copper mine at Herrngroundt, i. 450 — baths of Austria and Hungary j stone quarries, &c. i. 450 — dissection of an ostrich, ii. 535 Brown, John, a human liver appearing glandulous, iii. 248 — quantity of resin in the cortex eleutheriae, vi. 579 — experiments on Epsom salts, vi. 662 — observations and experiments on Prussian blue, vii. 6 — opinion respecting camphor, vii. 103j reply by Caspar Neuman, 631 — experiments on ambergris, vii. 668 Brown, Mr., (of Salisbury) success of inoculation at Salis- bury, x. 303 Brown, Rev. Lit., the monoculus apus described, viii. 163 Brown, Thomas, description of the flying fish, xiv. 423 Brown, Samuel, account of some Indian plants, iv. 310, 501, 586, 608, 636, 712, v. 61 Browning, J. effect of electricity on vegetables, ix. 306 — account of a dwarf, x. 209 — population of Bristol 1741 to 1750, x. 379 Brownrigg, Wm., m. d., of the new metal platina, x. 98 — remarks on Dr. Hales's method of distilling, x. 695 — experimental inquiry into the air in Spa water, xii. 235, xiii. 541 — specimens of native smalts, xiii. 575 Brownaea, descrip. of plants of this genus, xiii. 419, Bergius Bruckman, Ernest, salt-works in Hungary, vii. 386 Bruce, James, biographical account of, xiii. 672, .... Note — of the myrrh from Abyssinia, xiii. 672 Bruce, Rob., if. d., sensitive quality of the tree averrhoa carambola, xvi. 10 Bruni, Jos. Lawrence, m. d., of the Bologna bottles, ix. 102 — of a family overwhelmed, in their cottage, by the fall of snow, xi. 41 — of the hot baths of Vinadio in Piedmont, xi. 495 Bruyn, Cornelius le, biographical notice of, viii. 455. . Note Brydone, Patrick, palsy cured by electricity, xi. 163, 26*2 — a meteor observed at Tweedmouth, 1772, xiii. 415 — electrical experiments on hair, xiii. 416 — fatal effects of a thunder storm in Scotland, xvi. 186 Bubonocele, case of a, viii. 236, Amyand Buenos Ayres, longitude of, vi. 549, Halley Buffon, George Louis Leclerc, biographical account of, ix, 558, Note — description of his own burning-glass, ibid Bugden, J. unusual formation of the urinary parts, vii. 352 Biigge, Thomas, theory of pile driving, xiv. 498 — heliocentric longitude, and descending node of Saturn, xvi. 177 &c. of Venus and Mars, xvi. 621 — trigonometrical survey in Denmark, xvii. 353 Bulbous roots, rapid flowering of, in wat. vii. 466, Trieuwald vii. 46'7, ..Miller — on the raising of, in water, vii. 642, Curteis Bulkley, Sir R., on the Giant's Causeway in Ireland, iii. 529 — utility of cultivating maize, iii. 588 BYR INDEX. CAM 21 Bulkley, Sir R., propagation of elms by seed, in. 599 Bullet voided by urine, i, 286, Fairfax lodged in the head 30 years, extracted, v. 489, Fielding . near the gullet, viii. 227, Lord Carpenter Bulliald, Israel, biographical account of, i. 141 — of the new star in the whale's neck, and of that in An- dromeda's girdle, i. 142, 143, l6"2 — lunar eclipse observed at Paris, 1671, i. 639; 1675, ii. 187; 16'75, 221 — occultation of Saturn by the moon, 1678, ii. 432 — solar eclipse at Paris, 1684, iii. 69 Bullivant, Benj., natural history of New England, iv. 267 Bullock, Win. d. d., of the earthquake, Nov. 1, 1755, as felt in the lead mines, Derbyshire, x. 656* Bull's eye, occultations of, by the moon, l6'80, ii. 521, 522 Bunting, two species of, from Hudson's Bay, xiii. 340, Forster Burbot [Gadus Lota] description of, xiii. 410, Forster Burman, E. J., Aurora Bprealis at Upsal, vi. 54 Burnet, Tho., d. d., biographical account of, ii. 515 Burnet, Win,, of the ice mountains in Switzerland, v. 488 — longitude of New York by observation, vii. 49 — of a monstrous double female, xi. 144 Burney, Cha., Mus. D , of an infant musician, xiv. 513 Burning glasses, form and efficacy of, M. Villette's, i. 34 ; of a larger one of M. Villette's, 367 — account of Mr. Smethwick's, i. 226 Signor Settala's, i. 284 — of iron melted sooner than gold by the, i. 672 — immense effect of a new one in Germany, iii. 385 — expert, of the fusion of metals with, v. 501, . . Geoffroy — effects of M. Villette's, vi. 405, . . Harris & Desaguliers — M. de Buffon's, which burns at 66 feet distance, ix. 344, Needham — of the same burning at 150 feet, ibid, Nicolini — of his own constructing, descript. of ix. 558, . . Buffon. — of Kircher's opinion of those of Archimedes, x. 488, Parsons — of Hoesen's parabolic mirrors, xii. 589, • •• Wolfe Burning mountain, see Volcanoes Burning rock, in the East Indies, account of, xi. 600, Wood Burns, remedy for, ii. 475, Note Burrampooter (river) description of the, xv. 48, . . Rennell Burrough, James, m. d., account of a boulimia, iv. 503 Burroughs, John, lunar eclipse, 1725, Bristol, vii. 129 Burrow, Sir James, biographical account of, xi. 235 . . Note — earthquake in Surrey, 1758, ibid. Burton, Wm., m. d. viper-catchers' remedy for the bite of vipers, viii. 84 — histories of internal cancers, viii. 572 Burton, John, situation of the ancient Delgovitia, ix. 352 — extirpation of an excrescence from the womb, x. 71 Bury, Dr. Arthur, manuring in Devonshire with sea-sand, v. 432 Bussiere, Paul, an egg in the tuba fallopiana, iii. 605 — ways of cutting for the stone, iv. 358 — child born without a brain, iv. 373 — of a polypus in the lungs, iv. 488 — case of a triple bladder, iv. 545 — anatomy of the heart of a land-tortoise, v. 598 Bustard, anatomy of the, iii. 392 Butter, a substance like, falling in Ireland, iv. 78, Vans — same subject, ibid, Bp. of Cloyne Butterfield, Mr., way of making microscopes, ii. 445 — of some magnetical sand, iv. 310 Byam, Francis, impression of a fish on a stone, x. 628 — fall of rain at Antigua, 1751-4, ibid Byrd, Wm., account of a spotted negro, iv. 221 Byres, James, heat of the weather at Rome, 1/68, xii. 579 Byrom, John, on Mr. Jeake's plan of short-hand, ix. 530 Lodwick's plan of short-hand, ix. 534 Byssus, remarks on the vegetable, x.425,Bozej 426 Watson C Cabbage-bark- tree, of Jamaica, description of, xiv. 200, Wright Cacao Tree, description of, ii. 59 Cachalot, description of the blunt-headed, [Physeter cato- don] xiii. 57 Robertson Cactus Opuntia, of the insect bred thereon, xi. 674, Ellis Caesar (Julius) time and place of his descent on Britain, iii. 438, Halley Caesarian Operation, performed by a butcher, viii. 517 Cagua, John, cure of a fractured head, viii. 439 Caille, Abbe de la, biographical account of, xi. 472, Note — observations of the Comet of 1760, ibid — observations of the lunar parallax, proposed by Dr. Mas- kelyne, to be made at St. Helena, xi. 519 Calamine, way of digging and preparing, iii. 515, . . Pooley Calandrini, John, an aurora borealis, Oct. 1726, vii. 159 Calcination, cause of the increased weight of metals by, xvii. 245, Fordyce Calculus, experiments on human calculi, xvii. 6l Lane — nature of gouty and urinary concretions, xviii. 213, Woolaston — experiments and observations on urinary concretions, xviii. 254, Pearson — for all cases of Calculi, see Stone. Calendar, historical view of the changes in, ii. 496, Wood — disadvantage of adopting the Gregorian, iv. 434, Wallis — report on Mr. Dee's proposal for reforming the, iv. 437 — objections to the above plan of Mr. Dee, ibid. . . Greaves Calenture, account of a phrenitis, v. 105, Oliver Calep, Ralph, loss of the leg and thigh, by gangrene, v. 397 Calesh, description of a new sort of, iii. 170,. ... Sir R. B. Calf, account of a monstrous calf, i. 5, Boyle — with two heads, iv. 240, Southwell — of a monstrous calf, v. 365, Adams — instance of a cow with six calves, v. 486, .... Derham — monstrous head of, v. 668, Craig — double foetuses of calves, ix. 555, Watson Calf (Sea) see Sea Animals. California, account of, v. 458, Picolo Call, John, ancient carvings of the zodiac, in India, xiii. 321 Callus, supplying the loss of the os humeri, v. 378, Fowler part of the os femoris, v. 532, Sherman ; another case of the same nature, viii. 326 j another, viii. 503, Wright — of the hands and feet, microscopic observ. on, vi. 594, Leuwenhoek Camels, on the rate of travelling by, xvii. 38, .... Rennel Camelli, George Joseph, description of the tugus, or amomum, iv. 347 — medicinal virtues of the ignatia amara, iv. 356 — birds of the Philippine Isles, v. 45 — a treatise on amber, v. 119 — climbing plants of the Philippines, v. 155, 169, 184,188 — fishes, &c. of the Philippine Isles, v. 243 — quadrupeds of the Philippine Isles, v. 280 — serpents of the Philippine Isles, v. 307 — shells of the same, v. 363 — reptiles and insects of the same, v. 46l — spiders, beetles, &c. of the same, v. 640 Camelopardalis, description of, xiii, 7, Carteret 22 CAN INDEX. CAS Cameron, Thomas, m. d., fracture of the os pubis, ix. 370 Camillis, Joh Fr. de, disorder of Father Bolognini, ix. 16 Camps, two ancient camps in Hants, ix. 103, .... Wright < — condition of a Roman camp in Norfolk, ix. 682, Arderon Campani, Joseph and Matthew, some account of, i. 2. Note J., his improvement of optic glasses, i. 2 ■ *s glasses, Auzout on the superiority of, i. 23 ■ ■ ■ ' superiority of, over those of Divini, i. 46 Campbell, Colin, going of a clock in Jamaica, vii. 649 Campbell, George, on the roots of affected equations, vii. 264 Campbell, Robert, of a man's living 18 years on water, viii. 616 Camper, Peter, m. d., biograph. account of, xiv. 503, Note — organs of speech of the Orang Outang, xiv. 503 — of petrified bones found at Maestricht, xvi. 151 Camphor, distilled from thyme, vii. 93, 631 .... Neuman — opinion respecting, vii. 103, Brown — its efficacy in maniacal disorders, vii 206, .... Kinnier — experts, on the medicinal nature of, xii. 386,. . Alexander Canal, of Languedoc, plan of, i. 418, more particulars, 723 Canals, Treatise on, xiv. 593, Mann Canary seed, husbandry of, vi. 18 Tenison Cancer (disease) nature and cure of, iv. 279* Alliot — on the cure of, iv. 470, Geudron — extraordinary case of, iv. 643, Kay — account of two internal cancers, viii. 572, Burton — of the eye lids, nose, &c. called noli me tangere, cases of its cure, x. 602 Daviel — efficacy of green hemlock, in the cure of.xii. 37, Colebrook — observations on the matter of, xvi. 710, Crawford Cancer, Major, see Crab. Cancer stagnalis, description of this aquatic animal, xii. 390, King Candles, on the fluctuations of light emitted by, xvii. 371, Rumford — comparison of the light produced by wax, tallow, and oils, xvii. 372 Same Cane, Henry, change of colour in grasses and jessamine, vi. 489 Canella, see Cinnamon. Cange, C. du Frenedu, biograph. account of, ii. 442, Note Cannara, of a pagan temple at, v. 501, Stuart Canning, John, of the Arabian drugs tabashir, mamithsa and mamiraan, xii. 369 Cannon-balls, initial velocities of, xiv. 286, Hutton Cantharides, internal use of, iv. 696, Yonge Canton, the longitude of, iv. 318, Cassini Canton, John, a. m., biographical account of, x. 131, Note — method of making artificial magnets, ibid — electrical experiments, &c. x. 421, 532 — on the diurnal variation of the needle, xi. 421 — Transit of Venus over the sun, June 1761, xi. 555 — of some electrical experts, by Mr. Delaval, xi. 609 — experts, of the compressibility of water, xi. 665, xii. 151 — heat of the Bath and Bristol waters, xii. 420 — easy method of making a sort of phosphorus, xii. 579 — Transit of Venus and solar eclipse, 1769, xii. 6*32 — cause of the luminousness of the sea, xii. 681 Cantwell, Andrew, m. d., a glandular tumour in the pelvis, the effect of crude mercury, viii. 158 — palsy in the eye-lids, viii. 225 — account of a monstrous boy, viii. 325 — success of M. Daviel's method of extracting cataracts, xi. 625 Canula, see Instruments (Anatomical). Capasso, Dominico, lunar eclipse, Nov. 1724, Lisbon, vii. 55 — observations of Jupiter's satellites, 1723-4, ibid Cape Corse, observations at, iv. 201 Hillier Cape of Good Hope, manners and Nat. Hist, of, v. 359, Maxwell — on the longitude of, vi. 414, Halley Caracal, [Felis Caracal] description of the, xi. 474, Parsons and Note Carbone, John Bapt., lunar eclipse, Lisbon, 1724, vii. 55 — eclipse of Jupiter's first satellite, ibid — meridians of London, Paris, and Lisbon, ibid — latitude of Lisbon, &c. vii. 143 — solar eclipse at Lisbon, vii. 203 — lunar eclipse at Lisbon, ibid — astronomical observations at Lisbon, vii. 226, 247 — lunar eclipse at Rome, vii. 363 at Lisbon, vii. 418 — astronomical observations at Pekin, vii. 440 Carbon, expts. on carbonated hydrog. gas, xviii. 221, Henry Carbonic acid, experts, on the decomposition of, xvii. 221, Pearson — See Airs {Chemistry .) Cardan, extension of his rule in cubic equations, xiv. 453, 624, Maseres — on the first invention of his rule for cubic equations, xiv. 672, Same Cardioide, how to generate the curve, viii. 509, Castillione Caribbee Islands, observables at the, i. 176 — Queries respecting the natural history of, i. 227 ; an- swers to several of the queries, i. 230, Note — on the currents of sea at, x. 710, Peyssonel Carlsbad, mineral waters, account of, ix.688, .... Mounsey — virtue of, in the cure of the stone, xi. 56, . . Springsfield — analysis of, xi. 57, Note — nature and efficacy of, xi. 68, Miles — efficacy in the cure of the stone, compared with that of water and soap, xi. 16, Whytt Carlisle, George, m. d., of an uncommon large hernia, xii. 295 Carlisle, Anthony., of the distribution of the arteries of slowly-moving animals, xviii. 601 Carolina, animals and shells from, v. 209, Petiver — state of the weather at Charlestown, ix. 514, . . Lining Carp, management of carp in Prussia, xiii. 155, . . Forster — description of the cyprinus catostomus from Hudson's Bay, xiii 412, Forster Carpenter, Lord, a bullet lodged near the gullet, viii. 227 Carriage (by land,) improvement of machines for, iii. 62, Petty — description of a new calesh, iii 170, Sir R. B. Carte, Rev. Samuel, a tessellated work at Leicester, v. 643 Carteia, situation of the ancient, vi. 387, Conduit Carteret, Philip, account of the Patagonians, xiii. 7 — description of the Camelopardalis, ibid. Carthagena, in America, longitude of, vi. 620, .... HaJley Cartilages, nature and use of, iii. 465, Haver* — See Articulating Cartilages. Casano, Prince of, eruption of Vesuvius, 1737* viii- 36l — observation of red lights in the air, 1737* viii. 457 Cassegrain, M., invention of a catadioptrical telescope, i. 711 Cassini, James, biographical account of, iv. 228, .... Note — Lunar eclipse at Rotterdam, Oct. 1697, ibid. — latitude and longitude of Pekin, iv. 233 Cassini, John Dominic, biographical account of, i. 8. Note — on the comet of 1664 and 1665, i. 8 — rotation of Jupiter on its axis, i. 60 CAT INDEX. CAV 23 Cassini, John Dominic, period of the rotation of Mars, i. 81 — spots discovered in the planet Venus, i. 217 — account of the comet of 1668, i. 250 — spots discovered in the sun, i. 6l5 — spots in Jupiter, cause of, &c. i. 706 — observation at Paris of the comet of 1672, i. 70S — letters on his hypothesis of the sun's motion, i. 733 — discovery of two new planets about Saturn, ii. 50, 377 — on Hook's method of observing the earth's motion, ii. 135 — remarks on his and Flamsteed's observations of the lunar eclipse of Dec. 1675, ii- 280 — configuration of Jupiter's satellites, ii. 324 — spot in the sun, August, 16*76, ii. 332 — appearance of Saturn, 1676, ii- 333 — observation of the comet of 1677, ii. 390 — occultation of Jupiter by the moon, l679> ii- 481 — account of two new satellites of Saturn, iii. 292 — theory of Saturn's satellites corrected, iii. 363 — calculation of eclipses of Jupiter's first satellite, iii. 673 — longitude of Canton, iv. 318 — comet of Feb. l699> observed at Paris, iv. 354 — remarks on his orbit of the planets, v. 1 52, .... Gregory 1 — on the relative positions of Greenwich and Paris, xvi. 218 Cassowary, anatomy of the, iii. 393 Castagna, M. Ant. a mineral balsam found in Italy, i. 672 Castillione, remarks on a passage in his life of Sir I. Newton, xiii. 518, Winthrop — John, formation of the cardioide curve, viii. 509 — on Newton's binomial theorem, viii. 571 Castle-!eod waters, account of, xiii. 271 , Monro Castles, John, observations on sugar-ants, xvi. 688 Castor, a receipt for preserving it, iii. 442 — - the nature of, iii. 442, Note — found on dissecting a beaver, vii. 623, Mortimer — of the animal which produces it, ix. 688, .... Mounsey Castration of fish, Mr. Tull's method, x. 554 .... Watson Castro, Dr. de, case of an iliac passion from palsied intes- tines, x. l64 Castro Sarmento, Jacobus de, see Sarmento. Caswell, John, biographical notice of, iv. 40, Note ■ — quadrature of a portion of the epicycloid, iv. 40 — quadrature of the lunula of Hippocrates, iv. 455 — of a new baroscope, v. 120 Cat, dissection of a double cat, iii. 267, Mullen — see Tyger-cat Cat, Claude Nich. le, m. d. biographical account of, viii. 485, Note — on the foramen ovale of adults, ibid — figure of the urethra, ibid — on the formation of hydatids, viii. 495 ■ — consequences of an incomplete hernia, viii. 497 — a hammock for dressing- the wounds of unwieldy patients, viii. 654 — machine for reducing luxations of the arm, viii. 659 — on the operation for the stone, ix. 127 — an operation for the stone with the high apparatus, ix. 238 — double foetuses <.f calves, ix. 555 — glasses for preserving anatomical preparations, &c. ix. 6l8 — cure of clry gangrenes, ix 6'43 — instrument for extracting deep tumours, ix 645 — operat on for the stone on women, and instruments, ix. 650 — phenomena of the glass drop [Lacryma Batavica] ; the tempering of steel ; cause of effervescence, ix. 6'75 — a new trocart, x. 204 — on fungous excrescences of the bladder 3 a cutting forceps and canula for operating on, x. 214 Cat le, C.N. cases of hernias with sacks, x. 221 — a blind duct produced by the peritonaeum, x. 222 — strictures and carnosities of the urethra, ibid — dissection of a rupture, x. 227 — malignant fevers at Rouen, 1753-4, x. 567 — extraction and regeneration of part of the arm-bone, xii, 3*9 — a monstrous human foetus, xii. 362 — of a hydro-enterocele appearing like a hydro- sarcocele, xii. 445 Catacombs, of Rome, historical disquis. of, iv. 511,. . Monro Catadioptrical telescopes, with glass spec. viii. 393, Smith — see Telescopes Catalepsy, case of, viii. 15 Reynell Cataract (of the eye) observations on, vi. 602, . . Benevoli — dissection of eyes affected with, vii. 45 — on the substance of the, vii. 200, Rhaetus — Mr. Daviel's method of couching, x. 287, Hope xi. 625, . . Cantwelt — method of opening the cornea, x. 357> 414, .... Sharp — see Eye Cataract (waterfall) in Gottenburg river, iv. 525,. . Gordon Catarrhal disorder, remarks on, i. 612, Lower of an influenza in London, 1752, xi. 667 , Watson Catenaria, on the properties of this curve, iv. 184, 456, Gregory Caterpillars, that infest fruit-trees, origin of, iv. 233, Garden — and locusts at Wittemberg, 1732, vii. 645, . . Weidler — account of the cornel-caterpillar, ix. 500, .... Skelton — on the respiration of, ix. 504, Bonnet — descript. of the black canker-caterpillar, xv. 386, Marshall Catesby, Mark, biographical account of, vii. 432, .... Note — on birds of passage, ix. 327 Catheter, a new one for the stone, viii. 526, Cleland Catlyn, John, synopsis of Mercury's transit over the sun, October, 1743, viii. 612 — observation of a lunar eclipse, June, 1750, x. 72 Catoptrics, universal spherico-catoptric theorem, v. 184, Ditton — a catoptric microscope, viii. 73, Barker Cattle, see Distemper Caumont, Marquis de, an extraordinary stone from the blad- der, viii. 240 Cavallo, Tiberius, electricity of the atmosphere, Oct., 1775, xiv. 60 — new electrical experiments, xiv. 129, 180, 60S — thermometrical experts, and observs. xiv. 740, xv. 157 — a luminous appearance in the heavens, xv. 114 — description of an improved air-pump, xv. 453 — a meteor observed at Windsor, 1783, xv. 477 — magnetical experiments and observations, xvi. 57 — account of different electrometers, xvi. 354 — on the temperament of musical instruments, xvi. 442 Cavallo, description of a collector of electricity, xvi. 449 — micrometer for measuring small angles, xvii. 75 Cave, see Cavern. Cavendish, Lord Chas., thermo. for particular uses, xi. 138 Cavendish, Hon. Henry, experts, on factitious airs, xii. 298 — experiments on the Rathbone- place water, xii. 393 — electrical phaenomena accounted for, xiii. 223 — experiments to ascertain the nature of the electricity of the torpedo, xiv. 23 — account of the meteorological instruments of the r. s., xiv. 49 — of a new eudiometer, xv. 354 — on experiments of mercurial congelation, xv. 420 — experiments on air, xv. 481, 510 •> xvi. 15 24. CHA INDEX. CHI Cavendish, Hon. Henry, experiments by Mr. M'Nab on freezing mixtures at Hudson's Bay, xvi. 96, 425 — - conversion of airs into nitrous acid by the electric spark, xvi. 451 — height of the luminous arch seen Feb. 1784, xvi. 645 — on the civil year of the Hindoos, xvii. 249 — solution of a problem in nautical astronomy, xviii. 96 — experiments on the earth's density, xviii. 388 Caverhill, John, extent of the discoveries of the ancients in India, xii. 408 Cavern, with sulphureous vapour at Pyrmont, viii. 204, Seip — of an icy, and a noxious, in Hungary, viii. 293,. . Belius — Dr. Townson's on the above icy cavern, viii. 294, . . Note — at Killarny in Ireland, description of, viii. 400, . . Lucas — a remarkable one in Weredale, ix. 254, Durant — in chalk-cliffs near Norwich, ix. 490, Arderon — description of Dunmore cavern, Kilkenny, xiii. 368, Walker — some remarkable caves at Bareuth, xvii. 440, Margrave of Anspach Cauk-stone, description of, ii. 1 83, Lister Caul, see Omentum. Cay, , m. d., vitriolic waters at Eglingham, iv. 317 — medicinal virtues of ostracites, iv. 355 Cay, Robert, method of bending planks by sandheat, vi. 577 Caylus (M) his revival of an ancient method of painting, xi. 4, Mazeas Cazaud, Mr., cultivation of the sugar-cane, xiv. 521 — of sugar-cane mills, xiv. 683 Ceilan, see (Ceylon). Celio, Michael Ruben de, a mass of native iron found in South America, xvi. 369 Celsius, Andrew, a barometrical experiment, vii. 88 — observations on the aurora borealis, viii. 69 — solar eclipse at Rome, viii. 82 ; at Upsal, viii. 306 — explanation of some Swedish Runic characters, viii. 114 — lunar eclipse, 1736, London, viii. 116 Celtics, origin of .the ancient, iv. 414, Charmoye Centaurea orientalis, character of the, ix. 31, Haller Centrifugal force, effect of, on pendulums, viii. 627, Poleni Centrifugal bellows, see Bellows. Centripetal force, laws of, v. 435, Keill — on the inverse problem of, vi. 93, Same — on centripetal forces, xvi. 384, Waring Cepphus [Larus crepidatus] description of, xi. 541, Lysons Cerebellum, schirrhosity of the, ix. 49, Haller Cereus, Peruvianus, [Cactus] description of, vii. 441, Trew Cerf, M. le, proportion of moveables acting by levers, and wheel and pinion, xiv. 454 Cerusse, method of making, ii. 421, Vernati j disorders incident to the workmen employed, ibid Cestone, D'lacinto, on the generation of fleas, iv. 348 Ceylon, productions of, fishery, &c. i. 689, 692, Baldasus — some particulars of the natural history, &c. of, iv. 650, 711, Strachan — culture of tobacco at, iv. 666, Same — see Elephants. Chcetodon, a specimen of, from the South Sea, xiii. 137, Tyson — description of the ecan bonna, xvii. 284, Bell — of the teeth of the chcetodon nigricans, xv. 541, Andre Chais, Mr., method of inoculation on the coast of Barbary, xii. 527 Chales, C. F. Millet de, biographical notice of, ii. 184 Note Chalk, discovery of a chalk-pit in Rutland, xvii. 75, Barker Chalk-stones, of the gout, observ. on, iii. 122, Leuwenhoek Chalmers, Mr., a fire-ball bursting at sea, x. 19 Chamberlayne, John, thunder and lightning in Devonshire, — of the plague at Copenhagen, 1710, vi 75 — sunken island in the Humber recovered, vi 403 Chambers, Charles, earthquake of i755 at Madeira, x. 665 Chamois, anatomy of the, iii. 391 ' Chamaeleon, anatomical description of, i. 36Q • r*u*.. nf change of colour, 370,. ... y ' 3US^ f — of a particular species of, xii. 553, Parsons Chance, a problem in the doctrine of, xii. 41, 160' Baves Chaos and Creation of the world, opinion of, iii. 403 nav Chapman, Captain William, distillation of sea-water bv wood-ashes, xi. 243 J — fossil bones of an alligator, at Whitby, xi. 259 Chappe, M., transit of Venus, 1761, xi. 571 ~ 7~T" 1769, at California, xiii. 92 Characters, copied from the ruins of Persepolis, iii. 543 — some unknown ancient, iii. 574, Flower Aston — connection of the Egyptian and Chinese, xii.685, Morton — see Antiquities. Charas, Moses, biographical account of, i. 395 Note — on the poison of vipers, i. 411 Charlett, Arthur, d. d., of a colliery that took fire and blew up, v. 450 Charleton, Walter, m. d„ biog. account of, iii. 168 Note Charcoal, of use in cleansing putrid water, x. 644, '.* Note — electrical properties of, xiii. 370, Kinnersley — Russian method of recovering persons affected by the fumes of, xiv. 522, Guthrie Charr fish, description of, x. 609 Farrington Charts,divi»Jon of the meridians in sea-charts, iii. 224, Wallis — on the construction of, xi. 218, Mountaine — See Mercator's Chart. Chaulnes, Duke de, phosphoric acid from urine, xv. 41 1 Chazelles, M., solar eclipse, 1706, v. 297, Marseilles Cheek, caries and separation of the bone, vii. 21 6, Hardisway Cheltenham water, analysis of, viii. 523, Senckenberi Chermes, lacca, Nat.Hist. anddescrip. of, xviii.6'2,Roxburgh — see Gum Lac. & Cherries, to prevent their withering against too hot a wall, i- !60, Merret Cherubin (Father) biographical notice of, i. 666 Note. — on the theory of telescopes, ibid Cheselden, William, biographical account of, v. 671, Note — large human bones found near St. Albans, ibid — anatomical observations, vi. 76 — observ. on the recovery of sight after 13 years, vii. 235 — instruments for operating on the eye, vii. 237 — lateral operation for the stone, ix. 192 — effects of lixivium sapon. for the stone, ix. 193 Chesnut-trees, not indigenous in Britain, xii. 594, xiii. !*"-» Barrington — arguments in support of the opinion, that they are in- digenous in Britain, xiii. 110, Ducarel ; 116, Hasted Chester, on the salubrity of, xiii. 496, Haygarth — population and diseases of, 1774, xiv. 311, Same Cheston, Richard Browne, ossification of the thoracic duct, xiv. 684, 739 Chevalier, John, astronom. observ. Lisbon, 1753, x. 46l — eclipses of Jupiter's satellites, Lisbon, x. 567, xi. 158 — lunar eclipses, Lisbon, xi. 158, 284 Cheyne, George, u. d., biog. account of, v. 24,. . . . Note Chickens, manner of hatching at Cairo, ii. 413, . . Graves Child, crying in the womb, and remarks on, v. 538, Derham — born with the bowels hanging out, vii. 539, . . Amyand — extraordinary substance found in the body, x. 565, Guy — see Monsters, Ficius, Uterus, &c. CIM INDEX. CLE 25 Child, Wm., effects of lightning, use of conductors, x. 634 Child-birth, delivery of a child though the vagina was closed up, iv. 234 — see Parturition, Foetus, Monsters, Spc. Childrey, Jos., annual vicissitudes of tides, in animadversion on Wallis's hypothesis on the flux and reflux of the sea, i. 5l6; Wallis's reply, 520 Chimsera, (fish) description of the chimsera monstrosa, i. ipi Chiruney-pieces, curiously wrought in stone, iii. 98, Wallis China, of the bridges, and great wall at, i. 169, . .Kircher — manner of printing in, i. 36 1, Webb — essay on the Chinese characters, iii. 285, R. H. — chronology of Confucius, iii. 393 — account of the Islands Chusan and Ponto, iv. 69^, Cunninghame — account of the chronology of, vii. 427 — chronology and astronomy of, ix. 343, Costard — observations on natural history at, x. 387, D'Incarville — idea of the universal deluge at, x. 390, ........ Same — letters from, x. 411, Gaubil China cabinet, the contents of a, iv. 324, 345, 349, 352, Sloane China ware, on the manufacture of, i. 36 1, Webb — a manufacture at Milan, equal to real, i. 44 China stoves, description of the, xiii. 9^, Gramont China varnish, way of making several sorts, iv. 482, Sherard Chirac, Peter de, biographical account of, iv. 497 • • Note Chloranthus, description of the plant, xvi. 302, . . Swartz Chirograph, remarks on an ancient, viii. 64, Gale Choroides, see Vision. Chorography, solution of a chorographical problem, i. 563, Collins — three chorographic problems, iii. 235 Christian missionaries to the East, early success of, i. 122 Chronology, of the Indian Yugs, iv. 536, Note — Sir I. Newton's chronological index, vii. 89, . . Newton — remarks on Dissertations published in Paris respecting Sir Isaac Newton's index, vii. 172, 191, Halley — curious questions in, solved by Saunderson's method of unlimited equations, xii. 519, Horsefall — of the Hindoos, xvi. 742, Marsden — For Chinese chronology, see China. Chronometer, see Clock. Churchman, Walter, machine for raising water, vii. 663 Chusan, particulars of a voyage to, iv. 6y3, . . Cunninghame Churchill river, longitude, latitude, and magnetic declination, viii. 597 ', Middleton Chyle, passage of, into the lacteal veins, ii. 75, 554, . . Lister — experts, to ascertain the nature of, iii. 102 .... Musgrave — see Blood. Chylification, on the process of, iv. 81, Cowper Chymistry, of a salt extracted from a metal afterwards con- verted by heat into a gold-coloured liquid, i. 672, . . Lane — accidental discovery of a self-moving liquor, iii. 222, Boyle — see Acids, Salts, Colours, Effervescence. &c. Ciampini, John J., biographical account of, iii. 135, . . Note — account of the comet of 1 684, iii. 135 — remarks on asbestos, and on weaving it, iv. 604 Cicada, description of the cicada rhombea, xii. 99, . . Felton ■ septendecim, xii, 100, Collinson Cicindela volans, see Glow-Worm. Cicuta, see Hemlock. Cinchona, see Bark Peruvian . Cinnabar, experiments on, iii. 537, Leuwenhoek Cimento (Academy of) historical account of, iii. 87, . . Note — — — ■ philosophical experts, of, ibid. Cinnamon, method of extracting the oil, i. 307, . . Vernati — of the wild cinnamon tree, iii. 427, Sloane — of Ceylon, some particulars respecting, iv. 650, Strachan — cultivation of, at Ceylon, and varieties, vii. 340, Seba — account of "the laurus cinnamomum, x. 217, Watson — difference betweeen that of Ceylon and Malabar, xi. 313 White Cipolla, Rev. Lewis, astronomical observations at Pekin, xiii. 492 Circle, on the quadrature of the, i. 232, 251, .. Gregory — on Hobbes' doctrine of the quadrature, i. 623, . . Wallis — quantity of a degree in English measures, ii. 305 — quadrature of, ii. 547, Leibnitz : — on squaring the lunula of Hippocrates, iv.452, Wallis, &c. — construction of a quadratrix to, iv. 462 — properties of the circle, x. 469, Landen — proportion of the diameter to the circumference, xiv. 84 Hutton — improvement of Halley's quadrature of, xvii. 414 Helling — see Equations, Triangles, Polygons. Cirillo, Dominico, m. d , description of the manna tree, xiii. 46 — inoffensiveness of the tarantula's bite, xiii. 47 Civet-cat, on the anatomy of, ii. 291 Civita Turchino, subterraneous apartments and inscription* discovered at, xi. 706, Wilcox Clair, Father Paul, account of the New Phdippine Isles, v. 442 Clairaut, Alexis., biographical account of, viii. 118, Note — on the elliptical figure of the earth, viii. 1 19 — figure of the planets, viii. 207 earth, x. 328 — refrangibility of the rays of light, x. 530 Ctetck, Timothy, m. d., anatomical discoveries and obser- vations, viz. on injection of liquors into the blood, on transfusion, on the seminal vessels, &c. i. 246 — opinion respecting the testicles, i. 393 Clark, Sir John, effect of thunder on tree?, viii. 360 — a deer's horn found in the heart of an oak, ibid Clarke, Mr., Roman antiquities found near Devizes, iv. 548 Clarke, Charles, Patagonians of Magellan Straits, xii. 391. Clarke, Joseph, m. d., causes of the greater mortality of males than females, xvi. 122 Clarke, John, m. d., a monstrous birth with remarks, xvii. 312 — of a tumour in the placenta, xviii. 338 Clarke, Rev. John, bill of mortality in Bridgetown, Barba- does, ix. 5l6 Clarke, Robert., of a dog killed by the noise of musquet firing, iv. 221 — viscous excretions about the lungs, ibid. Clarke, Rev. Robt., calculus between the glans and pre- puce, ix. 635 Clarke, Sam., d. d., biographical account of, vii. 219, Note — on the force of moving bodies, ibid. Clays, a table of, iii. 85 Clayton, John, d. v., account of Virginia, iii. 544, 588, 600, 639 — experiments on the spirit of coals, viii. 295 — experiments on the nitrous particles in the air, viii, 296 — answers to queries relating to Virginia, viii. 328 — elasticity of steam, viii. 335 Clayton, Wm., account of the Falkland Islands, xiv. 1 Clegg, James, observations on dying black, xiii. 493 Cleland, Arch., a new catheter for the stone, viii. 526 — instruments for operations on the eye and ear, viii. 528 Clepsydra, description of a water-clock, ix. 236, !ian;ilton 26 coc INDEX. COL Clerk, Sir J., of the stylus and paper of the ancients, vii. 491 — solar eclipse, Edinburgh, viii. 175 Clerk, Wm., of stones in the stomach, kidney, and gall- bladder, iv. 357 Cliffs, of the Norfolk coast, strata, &c. of, ix. 272, Arderon Climate, change of, in different countries, ii. 309 — on the change in Italy, &c since 17 centuries, xii. 508, Barrington Cluverius, Philip, some account of, iv. 200 Circulation of the blood (see Blood). Clock, ascending on an inclined plane, ii. 439, , iii. 58, . . Gennes . Wheeler Wilkinson — to go with the sun, invention of, vi. 431, — - irregularity from heat and cold obviated, vi. 129, Graham — influence of two pendulum clocks on each other, viii. 320, 322, Ellicot — description of a water-clock, ix. 236, Hamilton — two methods of preventing an irregularity from heat and cold, x. 271, Ellicot — various inventions to avoid irregularity, x. 283, . . Short — on the going of Mr. Shelton's at St. Helena, xi. 604, Maskelyne — observations to prove the going of Mr. Ellicot* s at St. Helena, xi. 630, Mason ; remarks on the observations, xi. 631, Short; xii. 169, Maskelyne observations on the going of a clock in Pennsylvania, - xii. 578, Mason and Dixon _ , ... ■ - at the North Cape, xii. 644, Bayley __ — Otaheite, xiii. 175, Green and Cook — description of his astronomical clock, xiii. 215, Wollaston; account of the going of it, 382, 532, 650 . — See Pendulums. Clogher, Bp., of the sinking down of part of a hill, vi. 69 Clouds, rain, and vapours, accounted for, vii.323, Desaguliers Clustered animal flower, see Actinia Coal, pitch, oil, Sec. extracted from, iv. 168, ■ Ele — experiments on the spirit of, viii. 29-5, Clayton — method of maFmg coal balls at Liege, viii. 483, H anbury — impressions of plants on the slates of, xi. 123, Da Costa w- account of the Bovey coal, xi. 438, 512, Milles . — stupefaction caused by the smoke of, xi. 608, . . Frewen Coalmines, of a fire in, near Newcastle, ii. 358, Hodgson — strata of earths bored for coals, iv. 353, Maleverer — at Newcastle taking fire, v. 450, Charlett — strata of Staffordshire, v. 707, Bellers — specific gravity of the strata, v. 708, .... Hauksbee — strata of, at Mendip, vi. 401, vii. 118, Strachey — at Newcastle, on fire, ix. 254, Durant — explosion of air in a coal-pit, xiii. 432, Bernard Coati mundi, anatomical observations on, ii, 292 dissection of the, vi. 653, Mackenzie Cobalt and arsenic, method of preparing, v. 165, .... Krieg — nature of, vii. 171, Linck Cochineal, of a berry equal to cochineal as a die, i. 284 — on the production and preparation of, iii. 448 — observations on cochineal, v. 140, Leuwenhoek Cochineal insect, remarks on the coccus cacti, i. 1 84 — account of the coccus polonicus, vii. 51 1, .... Breyne — description of the coccus cacti, xi. 674, Ellis coccus polonicus, xii. 1 10, 320, Wolfe Coccus ilicis, of its use as a dye, i. 134, Note Coccus lacca, description of the, xv. 125, Kerr Coccus radicum, on the generation of the, vii. 575, Breyne Cock, Wm., machine for sounding depths, ix. 228 Cockburn, Wm., m. d., operation of a blister in the cure of fever, iv. 378 — medicinal question for solution, v. 164 Cockburn, Wm., m. p., emetics and purges adapted to the age and constitution, v. 250, 399 — table of doses of emetics, &c. v. 402 — discourse on the cure of fluxes, vi. 565 Cockin, Wm., meteoric appearance in a mist, xiv. 639 Cod fish, observ. on the spawn of, iv. 570,. . . . Leuwenhoek Coecum, exper. of cutting it from a bitch, ii. 66l, Musgrave — on the use of, iii. 1, Lister — 'of a hard substance extracted from, xiv. 186, . . Fynney Coffee, preparation of, introduction in Europe, &c. iv. 420 Houghton Coffee-tree, description of, iii. 622, Sloane Cohesion, queries respecting the cause of, vii. 336, Triewald Coins, of the pewter money of James 11. v. 199, Thoresby — and medals, method of taking impressions of, ix.30,Baker — see Money. — (Etruscan) a silver Samnite Etruscan, xi. 500, . . Swinton — observations on two ancient, xii. 112, Same — elucidation of a coin of Pcestum, xii. 562, Same — explanation of two coins or weights, xiii. 101, .... Same — (Norman) found at York, v. 253, Thoresby — (Parthian) with characters resembling the Palmyrene, x. 706, Swinton — with a Greek and Parthian legend, xi. 109, Same — explanation of two inedited, xii. 357, Same — (Persian) observations on five coins, xiii. 169, . . Same — (Phoenician) description of several, xi. 291, . . Same — explanation of a rare medal, xii. 441, . . Same — (Punic) explanation of a coin of Gozzo, xii. 56l,. . Same — — - — — another of Gozzo, xii. 563, . Same an inedited Punic coin, ibid Same — explanation of a Punic, or Phoenician, xiii. 101, Same — explanation of two inscriptions, xiii. 103, Same — (Roman) dug in Yorkshire, iv. 309, Thoresby — — — — found in Lincolnshire, iv. 675, .... Same Yorkshire, v. 263, Same v. 430, Same — of some clay moulds for, in Shropshire, ix. 356, Baker — golden, found at Silchester, ix. 602, Ward — of Domitian, with a two-horned rhinoceros, ix. 637, Sloane — of Chrispina with Greek inscription, xii. 275, . . Swinton — a medal found under Pompey's pillar, xii. 473, Montagu — a subaerated Plaetorian aedenarius, xiii. 282, . . Swinton — (Roman) a monogram on a quinarius explained, xiii. 530, Same — (Samnite) a Samnite Etruscan, xi. 501, Same — an inedited denarius, xi. 521, Same — a denarius of the Veturian family, xii. 562, xiii. 370, Same — explanation of two denarii, xii. 677 , Same — (Saxon) found in Suffolk, iii. 386 — (Swedish) descrip. of a coin or medal, v. 202, Thoresby — (Syracusan) a Greek coin of Queen Philistis, xiii. 18, Swinton Cold (Nat. Philos.) experimental history of, i. 4, 17, Boyle — on the nature of, i. 666, Petit — effect of, at Hudson's-bay, viii. 59 1, xiii. 27 — experiments on, at Glasgow, xiv. 705, xv. 129, Wilson — power of animals to produce it, xv. 147, • • • .Crawford — cause of the coldness of mountain summits, xv. 375, Darwin — of its influence on the health of the inhabitants of Lon- don, xviii. 1 , Heberden Cold (Experimental Philosophy,) experiments for suddenly producing a great degree of cold, i. 86 ; method of cooling liquors, i. 87, Boyle ; method of producing a greater degree of cold, i. 87, Not« COL INDEX. COM 27 Cold, produced by sal ammoniac with and without ebullition, ii. 654, Slare — production of artificial cold at Petersburgh, xi. 4S0, Himsel — of Braun's exper. on its production, xi. 544, . . Watson — exper. by Walker on the produc. of, xvi. 279, Beddoes — on cooling water below the freezing point, xvi. 409, Blagden — on lowering the point of congelation, xvi. 459, • • Same — production of artificial cold, xvi. 501, 579» xvii. 5(50, Walker — production of, by evaporation, xv. 157, Cavallo — on the cold of freezing mixtures, xv. 429, • • Cavendish — see Ice (Artificial.) — see Thermometer, Meteorological Observations, &c. Colden, Cadwallader, earthquake, Novem. 1755, at New York, x. 667 Cole, Wm., m. p., structure of fibres of the intestines, i. 295 — case of a false, though seeming, pregnancy, iii. 176' periodical convulsions, iii. 197 ____———— epileptic fits, iii. 198 — stones voided per penem, iii. 2l6 — of a purple fish, buxinum lapillus, iii. 252 — of grains like wheat, falling from the sky, iii. 356 — on the appearance of plum-stones voided by stool, v. 553 Cole, T. m. d., account of Mr. Bright, the fat man, of Essex, x. 184 Colebrook, Josiah, on the encaustic painting of the ancients, xi. 328, 332 — meteor seen at Bath, Oct. 1759, xi. 394 — efficacy of green hemlock taken internally for cancers, xii. 37, 254 Colepresse, Samuel, teeth cut at a very advanced age, i. 141 — two monstrous births in Devonshire, i. 167 - — magnetical experiments, i. 177 — an excellent liquor from mulberries and apple?, ibid — observation of tides at Plymouth, i. 227 — to counterfeit opal, and make red glass, i. 270 — the use of slate for covering houses, and mediod of trying the goodness of the sort, i. 370 — observations in mines and at sea, ii. 168 Coles, Edward, red colour produced by a mixture, iv. 167 Colic, an unusual case of, iv. 6*18, Davies — extraordinary effect of, vi. 288 St. Andre Collet, John, m. d., a pit of peat moss, in Berkshire, xi. 87 Collignon, Charles, m. d., of a body undecayed after long interment, xiii. 356 Collins, John, biographical account of, i 207, 338, . . Note — M. de Billy's method of finding the Julian period, de- monstrated, i. 207 — resolution of equations in numbers, i. 338 — solution of a chorographical problem, i. 563 — improvements in the science of algebra, iii. 38 Collinson, Peter, biographical account of, vii. 368, .... Note — opening of an ancient well in Kent, ibid — hardness of shells ; food of soals, ix. 15 — natural hist, and economy of the crab, ix. 203. x, 134 — observations on the May fly, ix. 290 — description of the belluga stone, ix. 335 — remarkable gleam of light from the sun, ix. 337 — earthquake 1755, at Pennyslvania, x. 667 — on the migration of swallows, martins, &c. xi. 425, 706 — of the cicada septendecim of North America, xii. 100 — bones of a mammoth found in North America, xii. 476 Collision, see Motion (force of moving bodies) Colman, Rev. Benjamin, earthquake at Boston, vii. 348 Colon, propendent from the abdomen 14 years, vi.483,Vater Colon, a remarkable disease of the, vii. 518, .... Huxham Colour, change of in grapes and jessamine, vi. 489,. • Cane — of the skin in differt. climates, cause of, ix. 50, Mitchell Colours (Chemistry) fixation of colours, and increasing of dyes, '{. 582, Lister — tincture given to a stone, iii. 273, Reisel — catalogue of simple and mixed, iii. 274, Waller — red colour produced by a mixture, iv. 167, Coles — to give various tinctures to water, iv. 243, Southwell — two inflammable liquors which, by mixture, produce a carnation colour without fermentation, iv.348,Geoffro7 — to give tinctures to spirituous liquors, vii. 120, Neuman — a dye produced from a berry of South Carolina, xii. 4, Lindo — receipts for a blue and yellow dye, xiii. 107, . . Woulfe — a new colouring substance from the South Sea, xiii. 595, Same — see Dyeing, Marble. Colour (Natural Philosophy) the colours of metallic par- ticles dependent on the specific gravity of the metal, xii. 179, • • Delaval — the prismatic colours produced on metallic surfaces by electrical explosions, xii. 510, Priestley — colours emitted by phosphorus, xiiii. 130, .... Beccaria — on experiments to try the power of different colours to retain heat, xiii. 371, Watson — power of the prismatic colours to heat and illuminate, xviii. 675, Herschel — for Doctrine of light and colours, see Light, (Optics) Colson, John, biographical account of, v. 334,. ..... Note — of cubic and biquadatic equations, v. 334 — of negativo-afflrmative arithmetic, vii. l63 — construction and use of spherical maps, viii. 6l Colt, a monstrous head of a, i. 29, Boyle Columbacristata, description of the, xiii. 267, . . Badenach Colwall, Daniel, of the English alum works, ii. 458 — art of making copperas, ii. 46l Combinations, and altern. doctrine of, v. 209, Thornycroft Combustion, on the light of bodies in, xv. 668, . . Morgan Comets, Hevelius's opinion of the matter of, i. 40 — Fontaney on the same subject, ii. 523 — Rosetti's opinion of, ii. 524 — Anthelme on the same, ibid — cause and motion of, ii. 546, Bernoulli — 370 in 4000 years, ii. 646, Zimmerman — nature of, v. 14, Gregory — elements for computing the motions of, ix. 48, .... Betts — on the parabolic paths of, ix. 648, Struyck — a ms in Pembroke College Cambridge respecting, x 209, Dunthorne — scheme of a comet's return, x. 6±5, Barker — point of attraction between a comet and the sun, xii. 405, Winthrop — method of computing the orbits of, xv. 651, . . . Zach Comets, (particular) of 1664, motion predicted by, i. 3, Auzout — 1664 and 1665, on the motion of, i. 8, Cassini — 1665, motion of, i. 14, Auzout — 1664, correction of a statement of, i. 53, Auzout and Hevelius — 1665, Hevelius's observation of, i. 115 — 1668, account from Italy, i. 250: Lisbon, 251, Cassini — 1668, seen at Brasil, by, ii. 135, Pere Estancel — 1672, seen at Dantzic, i. 696, Hevelius — 1672, observed at Paris, i. 708, Cassini — 16'77, ii. 390, Same — 1677, Dantzic; ii. 391, Hevelius D2 28 COM INDEX. CON Comet, 1677, observed at Greenwich, ii. 393, . . Flamsteed — 168I, — 1682, — 1683, — June, — Sept., — Feb., — Dec., — Clermont, ii. 522, Fontaney — Dantzic, ii. 557, Hevelius ii. 683, Same — Rome, iii. 135, Ciampini — Leipsic, iii. 346 1684, - 1686, - j 699, Paris, iv. 354, Cassini jfifa., Rome, v. 333, Ray 168O, - Coburg, vi. 1 14, Kirch — June, 1717, London, vi. 322 Halley — Jan., 17 18, Berlin, vi. 363, 621, Kirch __ 1723, Wanstead, vii. 13, Bradley — . —- Witham, vii. 15, .... Lord Paisley Albano, vii. 16, Bianchini — Oct., 1723, Bombay, vii. 176, .... Saunderson — Feb., 1732, sea, vii. 565 Dove — Jan. &c, 1737, — Oxford, viii. 149, Bradley — — Rome, viii. 133, Revillas Philadelphia, ibid, Kearsley ■ 1 Jamaica, viii. 154, Fuller Lisbon, viii. 155 Vanbrugh — 1739, p.irabolic orbit, viii. 515, Zanotti — 1743, Vienna, viii. 681, Frantz — , Oxford, ix. 47, Betts Sherborne, ix. 48, Same — 1742, Pekin, ix. 267, Hodgson — 1748, Pekin, x. 2, Hallerstein . — - — x. 3, Gaubil — 1757, Woolwich, xi. 169 Bradley the Hague, xi. 190,. . Klinkenberg — 1759, — 1760, — London, xi. 337, Bevis ibid, Munckley — London, xi. 428, Short ibid, Mitchell ibid, Munckley — ibid, Day ~ Paris, xi. 472, De la Caille — 1762, ————— Paris, xi. 645, De la Lande — 1759, the Hague, xi. 677, Gabry — 1764, course of, observed at Paris, xii. Il6, . .Messier — on the return of the comet of 1682, xii. 263, . . Same — two comets, 1766, observed at Paris, xii. 286, Same ; remarks on the same by M, Pingre, ibid. — observed April, 1766, at Kirknewton, xii. 287,. • Brice Jan., 1771, at Paris, xiii. 104, Messier — 1770, computation of its periodic time, xiv. 485, Lexel — 1781, observation of, xv. 154, Herschel ; 324,.. Note — 1783, observations of, xv. 464, 621, Pigott — return of the comet of 1532, l66l, predicted, xvi. 147, Maskelyne — 1786, observed at Windsor, xvi. 169, . . Miss Herschel remarks on it, xvi. 170, Herschel observ. of, at Chiselhursl, xvi. 186, Wollaston — 1788, observations of, xvi. 560, Herschel — 1791, observation of, xvii. 126, Same — 1793, xvii. 294, Same ibid, Maskelyne, &c. — 1794, discovery of, xvii. 335, Miss Herschel — 179*, xvii. 698, Same observations, ibid, Williams Commelinus, John, biographical account of, iv. 228, Note Compass (Sea) effect of a thunder storm on, ii. 309 — the same subject, iii. 18, Sir R. S. — new magnetical compass, iii. 381, Hire — invention and improvements of, iv. 639, 655, . . Wallis — electricity of glass affects the needle, ix. ?62, . . Robins — hghtning destroys its polarity, ix. 652, Waddel Compass (Sea) further account of the accident by lightning, ix. 653, Knight — description of his own, x. 64, Knight — improvements in the compass, x. 67, Smeaton — see Azimuth Compass, Magnet, Needle. Conception, see Foetus. Concoction, of food, hypothesis of the, iv. 400, . . Havers Concretion, remarkable concretions attached to the body of a calf, i. 5 nature of gouty, and urinary concretions, xviii. 213, Wollaston observ. &c. on urinary concretions, xviii. 254, Pearson see Stone. Condamine, Charles Marie de la, biographical account of, ix. 665, Note — declination of some southern stars, 1738, ibid — method of finding the hour of the night at sea, ibid — letter from Rome, on the mss. and antiquities of Her- culaneum ; on the figure of the earth, x. 709 Conductors (of lightning) an apparatus for powder-mills, xii. 127. Watson — on the construction of, and utility, xii. 143,.. .. Delaval hi xii. 147, Wilson — appearance of, on a ship's conductor, xiii. 35, . . . Winn — committee of a. s. on fixing them to the powder-maga- zines at Purfleet, xiii. 371 — on the proper shape of, xiii. 374, Wilson — opinion of the committee of r. s., on the proper shape of, xiii. 382 — superior efficacy of the pointed, xiii. 512, Henley — new exper. on the nature and use of, xiv. 337, Wilson — advantage of elevated pointed conductors, xiv.427,Nairne — remarks on Mr. Wilson's and Mr. Nairne's experiments respecting, xiv. 440, Musgrave — experts, on the proper termination of, xiv. 458, Wilson — see Lightning. Conduit, John, situation of ancient Carteia, vi. 387 Confervas, on the nature of, xii. 466, Ellis Conformation, see Monsters. Confucius, biographical account of, iii. 393, Note Congelation, a phenomenon in, xv. 423, Hutchins — experiments on lowering the point of, xvi. 459, Blagden — see Frost, Ice (Artificial) Conic Sections, some new properties in, xii. 124, Waring — compendious method of deducing, xiii. 458, .. ..Jones Conifera alypi folio, account of, iii. 514, Sloane Connecticut, natural curiosities at, i. 421, Winthrop Connor, Bernard, m.d., biograph. account of, iv. 10, Note — of a skeleton with backbone, ribs, &c. united, ibid Connought worm, (spinx elpenor) remarks on, iii. 120, Molyneux Conny, Robt. m. d., of a shower of fishes in Kent, iv. 302 Conringius, Herman, biographical account of, ii. 207, Note Consett, Rev. Thos., meteorological observations at Peters- burg, vii. 6l 1 Constantinople, latitude of, iii. 255, Greaves — first permission of printing at, vii. 556, Eames — answers to queries by Dr. Maty, viz., respecting the plague at, x. 580; population, ibid; polygamy, 582 j inoculation, ibid; printing, 583; state of learning, ibid, Parsons Contagion, how communicated, iii. 584, Slare ; 585 Note, Conti, Abbe, invention of the differential method or fluxions, vi. 389 ; Leibnitz's answer, 390 Contrayerva, account of the, vii. 506, . .• Houlston Convulsions, remarkable case of, iii. 197, Cole — of a remarkable kind, iv. 564, Ijrekid COR INDEX. COW *9 Convulsions, some extraordinary effects of, xi. 272, Watson — see Musk, JVorms. Conyers, John, a new hygroscope, ii. 346 — a cheap and useful pump, ii. 396' — improvement in the speaking-trumpet, ii. 445 Cook, Wm. rooms warmed by steam in pipes, ix. 125 — to stop the leakage of worm-eaten ships, ibid Cooke, Benj., extraordinary damp in a well, viii. 244 — ball of sulphur supposed to have been generated in the air, viii. 26'4 — a fire ball seen at Newport, viii. 550 — effects of mixing the farina of blossoms, ix. l69 — electricity of flannel, ix. 337, 532 — mixed breed of apples, from mixing the farina, ix.599, 6*85 — communicating of the jaundice in coitu, ix. 686 Cook, Capt. Jas., biographical account of, xiii. 174, Note — solar eclipse observed at Newfoundland, 1766, xii. 422 — astronomical observations at Otaheite, xiii. 174 — transit of Venus 176'9, at Otaheite, xiii. 176', 177 — magnetic-variation tables, observed in a voyage round the world, xiii. 169 — of the tide in the South Sea, xiii. 323, xiv. 71 — his plan for preserving the crew's health in his veyage round the world, xiv. 58 Cookson, I. m. i>., magnetism communicated by lightning, viii. 24, 25 — of a boy with a craving appetite, ix. 126 Cooper, Allen, effects of lightning on a ship, xiv. 510 Cooper, Sam., on a storm of thunder and lightning, xi. 327 Cooper, Wm., m. d., an extraordinary acephalous birth, xiii. 654 Cooper, Wm., n, d., observations of a meteor, August 1783, xv. 480^ Cooper, Astley, effect of the destruction of the membrana t} mpani of the ear, xviii. 626 Copenhagen, account of the plague at, 1711, vi. 7 '5, Chamberlayne Copernicus, a portrait of, presented to the r. s., xiv. 127, Wolfe Cope, John, an ancient date in Indian figures, viii. 32, 37 Copper, account of a mine at Herrngroundt, i. 450, Brown — account of some copper works, iii. 536, Davies transmutation of, into brass, iii. 535, Povey "~" effect of swallowing it, iv. 335, Baynard preservation of a dead body in a mine, vii. 41, . . Leyel ' from the waters of the Hungarian mines, viii. 236, Bell — of the Wicklow copper-springs, x. 280, 338, . . Henry — . x. 366, Bond — of the springs in Pennsylvania, xi. 3, Rutty — new method of assaying the ore, xiv. 608, ... Fordyce — discovery of gold at the Cronebane copper- mines, xvii. 677, Lloyd — chemical examination of some ancient copper arms and utensils, xviii. 41, Pearson Copperas, art of manufacturing, ii. 46 1, Col wall Coral, where found and how produced, i. 443, .... Gansius — nature and origin of, ii. 117 — microscopical observations on, v. 266, 426, Leuwenhoek — natural history of 5 x. 154, the madrepora described, 159 ; the myriozoon, 160, Donati — origin, its uses, of the animal causing it, &c. x. 257, Peysson el — of the isis ochracea from the East Indies, xi. 109 Corallines, observations on the sertularia neritina, x. 345 — different sorts of, x. 453, Ellis — animal nature of, x. 490, Same — opinion of the vegetable nature of, xi. 131, .... Baster Corallines, reply in refutation of their vegetable nature, xi. 134, j Ellis — see Zoophyta. Cork, experiments on the specific levity of, xii. 204, Wilkinson Cork, Bishop of, bones of a skeleton conjoined, viii. 5l6 — ancient temple inlreland viii. 715 ; a stone hatchet an ibid. Cor Leonis, occulted by the moon, ix. 336 Bevis Cormorant, anatomy of the, iii. 39 1 Corn, cause of the smut of, viii. 408, Pluche — on worms in the smut of, viii. 732, Needham — nature and cause of the blight in, ix. 6ll, Same ix. 612, xii. 209. . Notes. . Banks Corn, account of various diseases of, xii. 208 Tissot Cornea, see Eye, Cataract. Cornel-caterpillar, account of the, ix. 500 Skelton Cornelian, a specimen of white found at the Giant's Cause- way in Ireland, x. 382 Cornelio, Thos., m. d., of persons pretending to have been bitten by tarantulas, i. 719 } a disorder called in Italy the coccio maligno, ibid Cornish, Jas., on the torpidity of swallows, &c, xiii. 660 Cornwall, Capt., magnetic variations on a voyage, vi. 569 Cornua ammonis, see Amnonitw. Coronopus, efficacy against hydrophobia, viii. 269, Steward Corpse, see Bodies {Human). Correa de Serra, see Serra. Corse, John, natural history of the elephant, xviii. 444 — different species of Asiatic elephants, and on their mode of dentition, xviii. 509 Cortex Eleutheriae, quantity of resin in, vi. 579>- • . . Brown Cortex Winteranus, account of, iii. 586, Sloane Corundum stone from Asia, account of, xviii. 357, Greville — analytical description of the crystals of, xviii. 368, Count de Bourbon — specific gravity of, xviii. 377 > Various authorities Costa, Emanuel Mendes da, on belemnites, ix. 311 Note — two beautiful echinites, ix. 665 — remarks on the Dudley fossil, x. 401 — impressions of plants on the slates of coals, xi. 123 — on tincturing marble, xi. 324 — remarks on the terra tripolitana, xi. 372 — of a giant's-causeway in Scotland, xi. 535 Costard, Rev. George, biographical account of, ix. 168, Note — observation of a fiery meteor, July 1745, ix. 168 — chronology and astronomy of the Chinese, ix. 343 — on the year of the eclipse foretold by Thales, x. 310 — an eclipse mentioned by Xenophon, x. 356 — on the ages of Homer and Hesiod, x. 440 — translation of a passage in Ebn Younes, xiv. 133 Costiveness, extraordinary case of, v. 247, Sherman Cotes, Roger, biographical account of, vi. 77, Note — logometria, ibid — account of a meteor, March 1715, v. 477 Cotton, microscopical observations on, ii. 404, Leuwenhoek the seeds of, iii. 589, • - Same Cotton, Rev. Edw. d.d., of a loadstone dug in Devonshire, i. 149 Couching, see Cataract, Eye. Coughs, efficacy of blisters in, xi. 220, Whytt Courten, Wm., effects of poisons on animals, v. 684 Courzier, M., effect of the blood of a person dead of plague, vi. 586 Cow, anatomy of the Barbary cow, iii. 391 — see Distemper. Cowper, Wm., biographical account of, iii. 615, .. . .Note — experiments with Colbatch's styptic, iii. 615 CRO INDEX. CUR Cowper, process of chylification, iv. 81 — case of" a diseased kidney, iv. 105 — remarks on M. Dupre's tract relating to muscles of the neck, and a deformed human skull, iv. 368, 372 — - cure of the tendon of Achilles snapped asunder, iv. 376* — discovery of two glands with excretory ducts in the urethra, iv. 445 — polypus in the vena pulmonalis, iv. 563 — on the extremities of the arteries and veins, &c, iv. 680 — on aposthumations of the lungs, v. 41 — anatomy of the male opossum, v. 1 1 1 — ossifications and petrifactions of the arteries, v. 215 — remarks on a case of costiveness, v. 248 — of hydatids in a sheep's kidney, v. 315 — remarks on the effect of a gangrene, v. 398 — dissection of Mr. Dove's body, v. 698 a body dead of asthma, v. 705 Cox, Mr., of a pestilential fever caught by tapping a dropsi- cal corpse, viii. 338 Coxe, Dan., m. d., volatile salt from vegetables, ii. 124 — alcalizate not in vegetables previous to action of fire, ii. 158, 166 — improvement of soil in Cornwall with sea-sand, ii. 206 Coxe, Tho., transfusion of blood from a mangy to a sound dog, i. 159 Crabs, description of the Molucca crab (monoculus poly- phemus) iv. 325, Petiver natural history and economy of the cancer major, ix. 203, x# 134^ Collinson on the casting of their shells, x. 254, Parsons Crabs' eyes, remarks on, iv. 519, King and other earthy absorbents, ill effects of, viii. 452, Breyne produced from crawfish, and description, ix. 470, Baker Crabtree, Mr., remarks on the solar spots, v. 626 Craddock, Zach., a fiery meteor, May, 1744, ix. 46 Craig, Rev. John, quadrature of figures geometrically irra- tional, iv. 202 — quadrature of the logarithmic curve, iv. 318 — on the curve of quickest descent, iv. 542 , solid of least resistance, iv. 544 — method of determining the quadrature of figures, v. 24 — solution of Bernoulli's prob. on curves, v. 90 — on the length of curve lines, v. 406 <— method of making logarithms, v. 609 — head of a monstrous calf, v. 668 Cramer, Gabriel, biographical account of, vii. 393, . . Note — unusual aurora borealis at Geneva, ibid Cramp, followed by mortification, vi. 479, Steigerthall Crane (Bird) anatomy of the demoiselle (Numidian) iii. 392 — species of, from Hudson's Bay, xiii. 342, Forster Crane (Machine) improvements in the, vii. 369, Desaguliers Crawford, Adair, power of animals to produce cold, xv. 147 — observations on the matter of cancer, xvi. 710 . of the air extricated from animal substances by distillation and putrefaction, xvi. 715 — on sulphureous hepatic air, xvi. 726 Credibility of human testimony, on the degrees of, iv. 438 Creed, Rev. Mr., a machine for writing extempore volun- taries, ix. 332 Crell, F. L. F., m. d., experiments on putrefaction, xii. 163 — a new animal acid, xiv. 666, xv. l6'8 •— decomposition of the acid of borax, xviii. 4.57 Cressener, Rev. II., lunar eclipse, Streatham, 1710, v. 548 Crispe, Mr., articles found at Herculaneum, viii. 438 Crispina, see Coin. Crocker, - - , a meteor seen in the day, Dec. 1733, viii. 403 Crocodile, of the lacerta Gangetica, x. 712, . . . .Edwards Crocus autumnalis sativus, (see Saffron). Crornertie, Earl of, account of the mosses in Scotland, v. 63 Croich, Wm., his early musical genius, xiv. 513, Burney Crotor spicatum (lucidum) account of, xii. 529, .... Bergius Croone, Wm., m.d., biographical account of, iii. 133, Note Croonian lectures, (see Muscles). Crow, two species of, from Hudson's Bay, xiii. 332, Forster Croy, Prince of, solar eclipses, 1760-6, at Calais, ' xii. 347 Croyland Abbey, see Shrine. Cruikshank, Wm., experiments on the nerves and their reproduction; on the spinal marrow, xvii. 512 — observ. on the ova of rabbits after impregnation, xviii. 129 Cruquius, Nich., barom. thermom., &e. observations, vii. 2 Crural artery, see Arteru. Crusio, Charles, a remarkable cutaneous disease, x. 475 Cruwys, Samuel, Aurora borealis in Devon, vi. 442, 523 Crystal, experiments and optical observations on a sort of crystal from Iceland, i. 545, Bartholin ■ — nitrous crystals exhaled from the ground, i. 720, . . Lana — microscopical observations on, v. 204, .... Leuwenhoek — discovery of some rare crystals, vii. 187, ... . Scheuchzer — minute crystal stones, ix. 145, Parsons — attempt to account for the formation of, xii. 384, . . King — on the crystallizations of glass, xiv. 102, Keir Crystalline humour of the eye, observations on, iii.91,v.l55, Leuwenhoek — Mr. Hunter's observations on the nature and use of, xvii. 343> • : t Home — experiments on the same subject, xvii. 453, Same Cube, on the doubling of the, i. 328, Slusius Cubic Equations, see Equations. Cuculus indicator, (Honey-bird,) description of, xiv. 128, Sparman Cuckoo, natural history of the, xvi. 432, Jenner Cudvvorth, Ralph, d. d., biograph. account of, ii. 422, Note Cullum, Sir Dudley, a stove for hot-houses, iii. 658 Cullum, Rev. Sir Jn., a remarkable frost, June 23, 1783 xv. 604 Cumberland, Capt., art of bending planks by sand-heat vi. 577 Cuninghame, James, shells of the Island Ascension, iv. 418 — state of the barometer in China, iv. 426 — observ. of the thermometer andneedle near theCape,iv.500 — particulars of a voyage to Chusan in China, iv. 693 — list of plants from Chusan, v. 52 — journals of the weather at China, v. 149 Cuntur of Peru, (vultur gryphus) described, iii. 622, Sloane Cupping application of the pneumatic engine for, iv. 451, Luf kin Curiosities, description of some natural curiosities, iv. 644, Thoresby — seen in Denmark and Holland, v. 45, Oliver Currants, black, virtue of, for sore throats, viii. 47p, Baker Currents, of under-currents at the Straits, iii. 30, .... Smith — currents at the Straits accounted for, vii. 56 — of sea at the Antilles, x. 710, Peyssonel — on a current to the west of Scilly, xvii. 325, . Rennell Currie, James, m. d., biograp. account of, xvii. 193,. . Note — effects of immersion in hot and cold, fresh and salt wa- ter, on the living body, xvii. 193 Curteis, Wm., on raising bulbous roots in water, vii. 642 Curtis, Roger, natural history and population of Labradore xiii. 547, Curves, on the quantities of, i. 251 , Gregory — two problems on, solved, iv. 129, Newton — properties of the catenaria, iv. 184, 456, Same — on the quadrature of, iv. 202, Craig DAL INDEX. DEA 31 Curves, quadrature of the logarithmic curve, iv. 318, Craig — investigation of the curve of swiftest descent, iv. 335, Sault — methods of measuring curved figures, iv. 488, . . Wallis — solution of the probable curve of quickest descent, iv. 54-2, Craig — method of squaring some kinds of, iv. 658,. . . . Demoivre — solution of Bernoulli's problem on, iv. 90, Craig — length of curve lines, v. 406, Craig — of the 3d order, quadrature of, vi. 1S3, Demoivre — solution of a problem concerning, vi. 21 1, . . . . Newton — solution of Leibnitz, problem on, vi. 309, Taylor — construction and measure of, vi. 356, Maclaurin — of swiftest descent, vi. 374, Machin — to describe by right lines and angles, vi. 392, Maclaurin . — description of geometric curves vi. 46 1, Same — general method of describing, viii. 5, Braikenridge -■■ viii. 41, 43, .... Maclaurin — two new curve lines of the 3d order, viii. 392, . . Stone — how to generate the cardioide curve, viii. 509, Castillione — new method of comparing curve areas, xii. 545, Landen — new theorems for areas, xiii, 77 , Same — see Tangents. Cuticle, micros, observations on the, ii. 150, Leuwenhoek — see Skin. Cutting, Margaret, who could talk without a tongue, case of, viii. 586, Baker — further particulars of the case, ix. 375, Parsons Cuttle-fish, description of the American, xi. 286, .... Baker Cyanus [centaurea orientalis] account of, ix. 31,. . Haller Cycloids, synchronism of vibrations in, ii. 64, . . Brouncker — on quadrable cycloidal spaces, iv. 39, Wallis — and epicycloids, proposition for measuring, iv. 47, Halley — of descents in, &c. iv. 140, — knowledge of, as early as 1450, iv. 169, Wallis — see Epicycloid. Cyder, on the management of apple-trees for, i. 581 . . Reed — and perry, hints for improving, ix. l6'5, Miles Cygnus, figure of, and a new star in, i. 137, .... Hevelius Cylinders, best proportions of, for steam engines, x. 187, Blake Cylindroid, generation of a hyperbolical, i. 353, ; application of to the grinding of hyperbolical glasses, ibid . . Wren Cyprianus, Dr., child born with a wound in the breast, iv. 102 Cyprus [lawsonia inermis] account of the, ix. 583, Garcin Cyrillus, Nich., use of cold water in fevers, vii. 353 — eruption of Vesuvius, March 1730, vii. 554 — an earthquake in Naples 1731, vii. 606 — meteorological history of 1732, vii. 629 Cystis, of a scirrhous tumour inclosed in, vi. 73, . . Russel — watery cystises adhering to the peritonaeum, viii. 492,. Graham D Dalby, Isaac, longitudes of Dunkirk and Paris, xvii. 67 Dale, Samuel, bread made from turnips, iii. 598 — case of jaundice affecting the sight, iii. 652 — on the generation of eels, iv. 244 — account of several insects, iv. 350 — of Harwich, and the fossils found there, v. 124 — of the posthumous mss. of Mr. Ray, v. 310 — description of the moose deer in New England ; and a Virginian stag, viii. 102 — remarks on Ray's account of the flying squirrel, viii. 104 Dalmatia, observations on a journey through, ii. 284, Vernon Dalrymple, Alexander, on the formation of islands, xii, 454 Dalrymple, Alexander, method of the journal of a voyage to the East Indies, xiv. 386 Dampier's powder, efficacy of for the bite of a mad dog, viii. 204, Fuller. Dampier, George, a cure for the bite of mad animals, iv. 232 Dampier, William, biographical account of, iv. 141, . . Note Damps, subterraneous, persons killed by, i. 16, . . . . Moray — nature of choak-damp described, ibid, Note — in the mines of Hungary, i. 356, . , Brown — different sorts of, ii. 224, Jessop — in mines, ii. 244, Same — effect of in a coal-mine, ii. 398, Mostyn — on fire-damps in mines, ii. 474, Beaumont — of a Newcastle colliery taking fire, v. 450, . . Charrette — machine for extracting it from mines, vii. 208, Desaguiiers — effects and properties of, vii. 365 Greenwood — method of extracting from a coal-pit, viii. 612, Lowther — remarks on the cause of, viii. 77 , Desaguiiers — experiments on the inflammability of, viii. 77 ', .... Maud — extraordinary damp in a well, viii. 244, Cooke — see Mines, Fire, (subterraneous) Dantzick, of the plague at, in 1709, vi, 23 Darkness, a remarkable, at Detroit in Amer. xi. 6^5, Stirling Darwin, Erasmus, m. p., biograph. account of, xi. 124, Note — theory of the ascent of vapour, ibid — uncommon case of hoemoptysis, xi. 435 — experiments on animal fluids in the receiver, xiii. 536 — a new case in squinting, xiv. 297 — on artificial springs, xv. 627 — effect of the mechanical expansion of air, xvi. 272 Darwin, Robert Waring, m. d„ on the ocular spectra of light and colours, xvi. 121 Date, ancient, at Widgel Hal), viii. 32, 37, Cope ; remarks on it, 32, C9, . , Ward — ancient, at Worcester cathedral, viii. 39, Ward Rumsey church, viii. 478, Barlow — see Arabian Figures. Daval, Peter, comparative size of London and Paris, vii. 228 — an extraordinary rainbow, July, 1743, ix. 682 — distance of the sun from the earth, xi. 677 Davenport, Francis, of the tides at Tonquin, iii. 66 Davidson, George, of the bark-tree of St. Lucia, xv. 619 Daviel, M. — method of couching the cataract, x. 287 — cures of cancerous eye-lids, nose, &c, x. 602 Davies, — , m. d., of hydatids voided with urine, iv. 601 — of an unusual colic, iv. 61 8 Davies, David, account of some copper-works, iii. 536 Davies, Evan, effects of thunder, &c. in Wales, vii. 437 — practice of inoculation in Wales, 1722, vii. 615 Davies, Rich., m.d., specific gravities of various bodies, ix.536 Davies, Thomas, method of preserving animals for specimens, xiii. 34 Davis, Edward, child born with its bones displaced, ix. 351 Davis, Rev. John, a siphon similar in effect to the Wurtem- burg, iii. Ill Davis's quadrant, a water-level for, viii. 260, Leigh • mercurial level for, viii. 262 Same Dawes, Rev. Tho. of the plague at Aleppo, 1758, &c, xi.686 Dawkes, Thomas, account of a gigantic boy, ix. 95 Dawson, Ambrose, m. d., a long suppression of urine, xi. 376 Day, Mark, observations of the comet of 1760, xi. 428 Dead bodies, see Bodies. Dead Sea, analysis of the water of, viii. 555, Perry Deaf and dumb, method of teaching a language to, i. 464, Wallis — teaching to speak and understand, iv. 312, ....... Same 32 DEN INDEX. DES Deaf and dumb, a person, so born, taught to speak, v. 50, Ellis — a person who recovered his speech, &c. after a fever, v. 379, Martin Deafness, remarks on, i. 242, Holder; on perforating the tympanum, i. 243, Note — two deaf persons who understood from the lips' motion, v. 378, Waller — instruments for remedying, viii. 529, Cleland — efficacy of the cupping glass for its cure, xiii. 536,Darwin — see Ear. Dean, Forest, of the iron works at, ii. 41 8, Powle Deaths, by spontantaneous combust, various cases of, ix. 138 other cases, ix. 144, Hilliard Death-watch, description of the, iv. 319. Allen observations on the, iv. 576. v. 133, . . Derham Debenham,Thos., foetus extracted from the abdomen, x. 153 Debraw, John, on the sex of bees, xiv. 125 Decimals, of circulating decimal fractions, xii. 555, Robertson Deer, see Moose-Deer, Horns. Degg, Simon, m. d., of a large human skeleton, vii. 213 — case of longevity, ibid Degloss, Lewis, transit of Venus, 17o"9j xiii. 47, Dinapoor Degrees, see Latitude. Deidier, , m. d., biographical account of, vi. 557 Note — experiments on bile, ibid, and 56 1, 586 Delaval, Edward, electrical experiments, xi. 334, 589 — damage of St. Bride's steeple by lightning, 1764, xii. 140 — on lightning conductors, xii. 143 — the colours of metals in minute particles dependent on their specific gravity, xii. 179 Delgovitia, situation of the ancient town of, ix. 21 6, Knowlton ix. 352, Burton ix. 354, Drake Delirium, a person without an ear for music, singing well when delirious, ix. 370, Doddridge Delisle, Joseph Nich., biographical account of, vii. 335, Note — eclipses of Jupiter's satellites, at Petersburg, vii. 335 — construction of quicksilver thermometers, viii. 66 — proposal for measuring the earth in Russia, viii. 124 — actual admeasurement of the basis, viii. 134 — parallax of Mars and of the sun, x. 454 Deluge (universal) opinion of, Hi. 493, Ray — on the cause of, vii. 33, 35, Halley — idea of in China, x. 3 Leuwenhoek — on the particles and structure of, vi. 605, Same — found in Brazil, vii. 508, Sarmento -— specific gravity of, ix. 147, Ellicot — analytical inquiry into their nature, xviii. 97, . . Tennant — table of specific gravities of, xviii. 378 Diaphragm, on the structure of, vi. 671, .... Leuwenhoek t- rupture of, in an infant, ix. 187, Fothergill Diaries, meteorological, see Meteorological Observations. picquemare, Abbe, of sea anemonies, xiii.460, 633. xiv. 129 Diemerbroeck, Isbrand Van, biograp. notice of, ii. 148, Note Differential, see Fluxions. Digestion, theory of, iii. 69, . Leigh Digestion, experiments on, iii. 71, Musgrave — hypothesis of the concoction of food, iv. 400, Havers Digges, Edward, on the management of silk-worms, i. 12 Dingley, Robert, on the gems used by the ancients, ix. 345 — irregularity of the tide in the Thames, x. 694 Dionysius of Piacenza, of some animals in Congo and Brazil, ii. 484 Diophantus, biographical notice of, i. 604 Note Dioptrics, a problem in, iii. 329, Molyneux — to find the foci of all optic glasses, iii. 393, .... Halley — see Optics. Dipping needle, see Needle. Diseases, peculiar to Turkey, ii. 6l — arising from the use of bad rye, in France, ii. 357 — analogy between the motion of, and tides, iii. 551, Paschal — of the Russians, Tartars, &c, iv. 420, Lloyd — of India and manner of cure, vi. 52, Papin — an eruptive disease of Siberia, x. 355, Gmelin — see Diseases under their respective appellations — see Distemper. Diseased Cattle, see Cattle, Distemper. Dissection (of Brute Animals) chimaera monstrosa, i. 191; a lion, i. 192 — of a porpoise, i. 639, Ray — an ostrich, ii. 334, Brown — a rattlesnake, ii. 56l, Tyson — of a preternat. glandulous substance from an ox, iii. 116 — a monstrous double kitten, iii. 207, Mullen — of a rat, iii. 582 — a paraquet, iii. 650, Waller — the scallop, iv. 170, Lister — opossum, iv. 248, Tyson — excision of part of a dog's intestines, v. 4, Shipton — of a hare, v. 314, Marchetti — an elephant, v. 557, Blair — heart of a land tortoise, v. 598 — of the coati mondi, vi. 656, Mackenzie — an ostrich, vii. 69, 392, Ranby - vii. 150, Warren — of the marmot (mus Alpinus) vii. 181, .... Scheuhzer — of an hermaphrodite lobster, vii. 398, Nicholls — of a female beaver, vii. 623, Mortimer — of a sea-calf [phoca barbata] viii. 658, Parsons — see Anatomy (comparative.) — (Human Bodies) of a body dead of unusual disorders, i. 199, Fairfax — of Thomas Parr, aged 152, i. 321, Harvey — of a woman who died of apoplexy, iii. 1 84, .... Cole — Mr. Smith's body (vesicles in the bladder) iii. 374, Tyson — body of a maid dead of ascites, iii. 606, Turner — of a woman with dropsy in the uterus, iii. 607, . . Same — of a child of 6 years, with a face like a woman's, iv. 31, Sampson — in consequence of a diseased kidney, iv. 105,. . Cowper — of a woman dead of dropsy, iv. 114, Preston — of a boy who died suddenly, iv. 122, Same — of the body of Mr. Malpighi, iv. 151, Lancisi — observations at various dissections, iv. 207, .... Gaillard — of a woman dead in child-bed, iv. 560, Silvestre — of a dropsical body, v. 219, Lafage — of a man who died at 130 years old, v. 299, • • • . Keill — of a person dead of an ulcer in the kidney, v. 554, Douglass — the body of Mr. Dove, v. 698, Cowper — a body dead of asthma, v. 705, Same — of a woman supposed to be pregnant, vi. 242, Hollings — a child much emaciated, vi. 307, Blair E 34 DOB INDEX. DOU Dissection of a person aged 109, vi. 652, . . Scheucbzer dead of stone, vi. 657, Williams , . ibid, Hardisway — several human bodies, vii. 226, Ranby — of a remarkable hydrops ovarii, vii. 533, Belchier — of a body dead by swallowing crude mercury, viii. 80, Madden — of an inguinal rupture, viii. 92, Amyand — glandular tumour in the pelvis, viii. 158, .... Cantwell — a foetus in the abdomen, viii. 488, Bromfield — of a body dead of stone, viii. 557, Bell — of internal cancers, viii. 572, Burton — on account of a dropsy, viii. 607, Short — of a head for hydrocephalus, viii. 622, Baster — of a woman 100 years old, observ. on, ix. 348, Haller — two conjoined female children, ix. 568, Parsons — of a body dead of an iliac passion, x. 164, . . De Castro ■ of hydrophobia, x. 245, . . . . Wilbraham — the body of king George the II., xi. 574, .... Nicholls — — — — James Bradley, d. d., xi. 663, Lysons — of a body dead of asthma, xii. 145, Watson — the body of Dr. Maty, xiv. 217, Hunter — of an extraordinary introsusception, xvi. 1 19, . . Lettsom — see Anatomy. Distances, from one station, meas. by the telescope, i. 43 — see Parallax, Sun, Earth, Moon, &c. Distemper, of the coccio maligno in Italy, i. 719 — an extraordinary sickness among the Indians in New England, xii. 170, Oliver — (of Cattle) inoculation recommended for, ii. 587, Note — account of in Italy, vi. 78, Ramazzini — a recipe for, vi. 80 — in the neighbourhood of London, 1714, vi. 375,. . Bates — hint of a method of cure, vi. 379> Note — in the Venetian territories, 17H> vi. 481, . . Michelotti — near London, and remedies, 1745, ix. 171, 177, 184, Mortimer ; further particulars in various communica- tions, 185 — on burying in lime, the cattle dead of, ix. 255, Parsons — usefulness of inoculation to prevent, xi. 206,. . . Layard — nature of, xiv. 723, , Same Distilling, application of receivers to retorts, ix. 96, Langrish — by air and fire, x. 635, Hales — remarks on Dr. Hales's method, x. 694, .... Brownrigg — Dr. Hales's method applied to the steam engine, xi. 81, Fitzgerald — distillation of acids, volatile alkalies, &c, xii. 484, Woulfe Dittany, destructive of rattle-snakes, i. 16 Ditton, Humphrey, biographical account of, v. 17 . . Note — on the tangents of curves and conic sections, ibid — universal spherico-catoptric theorem, v. 184 Diving, means of supplying air to divers, vi. 258, 521, Halley — improvement in the diving-bell, viii. 98, .... Triewald Divini, Eustachio de, some account of, i. 46, Note — superiority of his glasses asserted, i. 68 — on rock crystal for optic glasses, i. 134 — a new microscope, i. 301 Division, of right lines, surfaces, and solids, xiii. 729, Glenie Divisors, properties of the sum of, xvi. 497, .... Waring Dixon, Jeremiah, observations for determining the length of a degree of latitude, made in Maryland and Pennsyl- vania, xii. 566 — on the going of a clock in Pennsylvania, xii. 578 — transit of. Venus 1769, at xii. 044, Hammerfost Dixon, Wm., description of some vegetable balls, x. 280 Dobbs, Arthur, a parhelion seen in Ireland, vi. 582 — of an aurora borealis, and its cause, vii. 155 Dobbs, Arthur, lunar eclipse at Carrickfergus, vii. 352 — distance between Asia and America, ix. 341 — natural history and economy of bees, x. 78 Dobrzensky, preservative against infection, ii. 492 Dobson, Matthew, m. d., petrified stratum from the waters at Matlock, xiii. 510 — experiments in a heated room, xiii. 687 — on evaporation as a test of dryness, xiv. 137 — account of the harmattan wind, xv. 23 Dobyns, John, stones found in the kidneys, vii. 238 Dod, Pierce, m. d., aneurism of the aorta dissected, vii. 229 — discharge of bloody urine in the small pox, viii, 708 Dodart, Denis, biographical account of, ii. 484, .... Note Doddridge, Philip, biographical account of, ix. 557, . . Note — of a person, not musical, singing well in a delirium, ix. 370 — of a wether giving suck to a lamb ; of a monstrous lamb, ix. 557 — phenomena accompanying an earthquake, x. 114 Dodington, John, of the Aponensian baths near Padua, i. 720 Dodson, James, biographical account of, x. 223, .... Note — an improvement in Bills of mortality, ibid — on infinite series and logarithms, x. 396 — on annuities and survivorship, x. 548 — utility of observations of magnetic variation, x. 556 — table of the value of annuities constructed according to the rule of Dr. Braikenridge, xi. 55 — tables of magnetic variation, 1750 to 1756, xi. 149 Dolaeus, John, biographical notice of, iii. 73 Note Dollond, John, biographical account of, x. 341, ... . Note — improvement of refracting telescopes, ibid — contrivance for measuring small angles, x. 364, 462 — remarks on Euler's theorem on aberrations in object glasses, x. 402 — to remedy the different refrangibility of light in object glasses, xi. 267 Dollond, Peter, remedy of the defect in object glasses arising from the refrangibility of light, xii. 194 — improvement of Hadley's quadrant, xiii. 291 — equatorial instru. for correcting errors in refrac, xiv. 524 Dog, diseases of dogs, and cure, iii. 410, Mayerne — killed by the noise of musquetry, iv. 221, .... Clarke — similarity in species to the wolf and jackal, xvi. 26i, 562, Hunter — dissection of an hermaphrodite dog, xviii. 485, . . Home Dog, mad, recipe for the cure of the bite, iii. 362, Gourdon — remedies for the bite of, iii. 410, Mayerne iv. 232, Dampier — effects of the bite of, iv. 645, De la Prvme — cases of the bite cured, iv. 286, Lister — efficacy of coronopus in the bite of, viii. 269, Steward — case of the bite of, cured, ix. 97 > Peters — cure of the bite of, with vinegar, xii. 221, Earl Morton — see Hydrophobia. Dog, mercury, strange effects from eating it, iii. 575, Sloane Donati, Vitalino, m. d., biographical notice of, x. 154, Note — natural history of coral, ibid the Adriatic Sea, x. 704 Donius, John Baptist, on restoring the salubrity of the country about Rome, i. 539 Doris radiata, description of the, xi. 695, Dupont Doudy, Sam., strange symptom of a hydrops pectoris, iv. 131 Douglas, Charles, of the temperature of the sea on the coasts of Lapland and Norway, xiii. 9 Douglas, James, m. d., biographical account of, v. 318, Note — an ossified tumour in the neck, v. 285 — - of a hydrops ovarii, &c, v. 318 — an ulcerated kidney, v. 554 DUC INDEX. DYN 35 Douglas, James, m. d., enlargement of the left ventricle of the heart, vi. 181 — observations on the glands of the spleen, vi. 26*2 fracture of the upper part of the thigh-bone, ibid — description of the flamingo or phcenicopterus, vi. 268 — a method of cutting for the stone, vi. 580 — description of the crocus autumnalis sativus, vi. 678 — two methods of operating in cases of stone, vii. 200 — culture and management of saffron, vii. 278 — of the different sorts of ipecacuanha, vii. 356* — successful use of bark in mortifications, vii. 572 Douglas, Robert, observations of magnetic variation, xiii. 729 Douglas, Sylvester, a blue substance in peat-moss, xii. 547 — of Tokay and other Hungarian wines, xiii. 451 Dove, John, large shower of pumice stones at sea, viii. 234 — account of the comet of February, 1732, vii. 565 Doz, Vincent, Transit of Venus, 1769, at California, xiii. 91 Dragon fly, see Libella. Drake, Francis, situation of the ancient Delgovitia, ix. 354 — bones of a foetus discharged near the navel, ix. 456 Drake, J., m.d. influence of respiration on the heart's mo- tion, iv. 698 Drawing, outlines in perspective, an instrument for, i. 325, Wren — machine for, or prosographic parallelogram, ii. 84, Sinclair Dream, recovery of speech by fright in a dream, ix. 465, Squire Drelincourt, Charles, m. r>., biograph. notice, iii. 141, Note — anatomical experiments, ibid Drills, on the magnetism of, iv. 332, Ballard Drink, see Food. Dromedary, anatomical description of the, i. 372 Dropsy, acquired by a person being too much in the air, i. 49 — remarkable case of, ii. 152, . » Tulpius — in the ovarium, ii. 437, Sampson — in the tunics of the uterus, iii. 607, Turner — reflections on the causes of, iv. 114, Preston — in the chest, strange symptom of, iv. 131 Doudy — in the ovarium, iv. 375, Sloane — dissection of a dropsical body, v. 219, Lafage — in the ovarium, v. 31 8, Douglas — distention of the gall bladder, v. 667 , Yonge — in the ovarium, cure of, vii. 2, Houstoun — case of a woman tapped 57 times, vii. 533, Belchier ■ 67 times, ibid, Note — a fever caught by tapping a dropsical corpse, viii. 338 — account of an extraordinary,, viii. 607, Short — caused by the want of a kidney, ix. 292, Glass — cases o£ cures by sweet-oil, x. 566, Oliver — in the chest, successful operation for, xii. 358, Moreland — a remarkable case of, xiv. 481, Latham — in the ovarium, xv. 6*25 Martineau — see Tapping, Hydrocephalus. Drowning, cause of death by, iv. 270, Note — observations on drowned persons, v. 264, Becker — of a girl under water a quarter of an hour without being drowned, viii. 337 Green — a boy kept afloat on the sea half an hour, xi.72, Robertson Dryander, Jonas, of the benjamin tree of Sumatra, xvi. 287 Dryness, of the year 1788, xvi. 529, Hutchinson — see Meteorological Observations. Dublin, see Population. — arcbbp. of, manuring with sea shells in Ireland, v. 403 Ducarel, Andrew Coltee, ll. d., chesnut trees indigenous in England, xiii. 116 — on the early cultivation of botany, in England, xiii. 383 Ducts, see Biliary Ducts, Thoracic Duct, Excretory Ducts. Dudley, Sir Matt, insects in the bark of elm and ash, v. 193 Dudley, Paul, sugar from the maple tree, vi. 458 — poison-wood tree of New England, vi. 507 — method of finding wild honey in New England, vi. 509 — account of the moose deer in America, vi. 515 — ' falls of Niagara, vi. 574 — of molasses from apples, vi. 6l8 — on the degenerating of smelts, vi. 619 — accouist of the rattle-snake, vi. 642 — cure by sweating in hot turf; description of the sweat- ing rooms of the Indians, vii. 37 Dudley — on vegetation in New England, vii. 57 — natural history of the whale, vii. 78 — large stone taken out of a horse, vii. 187 — of eardiquakes in New England, viii. 22 Dufay, M., efficacy of olive oil for vipers' bites, viii. 267 Dugard, Rev. Samuel, an uncommon hemorrhage, ii. 169 Duillier, Facio, solar eclipse, 1706, Geneva, v. 296 Dumb, see Deaf and Dumb, Speech. Dunbar, of basaltic pillars at, xi. 533, Bp. of Ossory Dunmore Park, of a remarkable cavern at, xiii. 63, "Walker Dunn, Samuel, transit of Venus over the sun, June, 1761, xi. 555 — cause of the apparent greater size of the Sun and Moon near the horizon, xi. 6ll — observations of a solar eclipse 1762, xi. 667 — appulse of the moon to Jupiter, Chelsea, 1762, xi. 685 — defence of Mercator's chart from the censure of, xi.696, West — a meteor resembling a parhelion, xii. 39 — solar eclipse 1764 observed at Brompton, xii. 114, — lunar eclipse 1764 observed at Brompton, xii. 1 14 — transit of Venus 1761, 1769> xiii. 14 Dunthorne, Rev. Rich., biograph. account of, ix. 669, Note — on the motion of the moon, ix. 318 — on the moon's accelerated motion, ix. 669 — account of a latin m. s., on comets, x. 209 — tables of the motions of Jupiter's satellites, xi. 535 Dura Mater, cause of the motion of, v. 71* Ridley — present opinion of the cause of its motion, v. 73, . . Note — dissertation on, v. 6l 8, Pacchionus Dupont, Andrew Peter, descrip. of a doris radiata, xi. 625 Dupre, M., of the muscles which join the head and neck, iv. 368 — of a deformed human skull, iv. 372 Durant, J., a coal mine on fire ; a steam depositing a blue sediment ^ large cavern in Weredale, ix. 254 Durston, William, m. d., on an excessive swelling of the breasts, i. 393, 402, 405 — a monstrous birth, with anatomical observations, i. 531 Dust, a shower of in Shetland, xi. 138, Mitchell — see Ashes. Dutton, Wm., a meteor seen, Oct. 1759, in Essex, xi. 395 Dwarf, compared with a child of 4 years, x. 53, . . Arderon — account of a dwarf, x. 209, Browning Dyer, Rev. Mr., effects of thunder and lightning in Corn- wall, xi. 86 Dyeing, of dyeing roots found at Hudson's Bay, xiii. 282, Forster — experiments on dyeing black, xiii. 493, Clegg — see Colours (Chemistry). Dymond, Joseph, transit of Venus, 1769. at Hudson's Bay, xii. 682 — meteorological observations at Hudson's Bay, 1 768-9, xiii. 32 Dynamics, experts, on the fall of bodies, v. 612, Hauksbee Ra 36 EAR INDEX. EAR Dynamics, ascent of oil up planes, v. 659, Same water between planes, v. 706, Taylor _____ -_ _____ . v. 707, vi. 40, Hauksbee spirit of wine between planes, vi. 40, 41, . . Same — dynamical principles, ix. 217* • Jurin — see Motion (Force of moving bodies). Dysentery, epidemical in London, 1762, xi. 667, Watson Eagle, anatomy of the, iii. 392 Eagles (Roman standard) account of the, vi. 39, Musgrave Eames, John, biographical account of, vii. lfjfj, Note — force of moving bodies in collision with non-elastic bodies, ibid — remarks on the force of moving bodies, vii. 169 — first permission to print at Constantinople, vii. 556 — account of Newton's book on fluxions, by Colson, viii. 88 . — Muller's book on conic sections, viii. 145 — magnet, with more than two poles, viii. 246 — account of " Kersseboom on the population of Holland," viii. 253 — — Celsius de Figura Telluris, viii. 413 Jurin de Vi Motrice, viii. 46 1 . Klein, Piscium Hist. Nat. viii 551 Ear, structure of, and organ of hearing, iv. 448, Vieussens — treatise on the human, v. 220, Valsalva — anatomical remarks on, v. 365, Adams — organ of hearing in an elephant, vi. 382, Blair — instruments for operations on, viii. 528, Cleland — operation for remedying an obstruction of the eustachian tube, x. 609, Wathen — case of a boy who lost the malleus of each, and one of the incuses, xi. 574, Morant — structure and use of the membrana tympani, xviii. 566, Home — effect of the destruction of the membrana tympani, xviii. 626, Cooper — mode of hearing after destruction of the membrana tympani, xviii. 630, Home — for the hearing of fishes, see Fish. — see Deafness. Earnshaw, Wm., m.d., of an ulcer in the groin which emitted the intestinal faeces, iii. 230 Earth, (planet) its moon similar to the satel. of Jupiter, i. 25 — and moon, changes in, to be seen by their respective in- habitants, i, 41 — to find the distance of the sun and moon from the, i. 53 — and moon, the doctrine that they have one common centre of gravity, supported, i. 102, Wallis — Angeli's and Riccioli's controv. the motion of, i. 254 — of its motion, ii. 126, Hook ' ii. 135, Huygens — — — — ibid, Cassini — measure of the meridian, ii. 193, Picard — difference of admeasurements in differ, lat., ii. 198, Note — circumference and diameter of, ii. 305, .... Norwood — real admeasurement of, ii. 306, Note — its internal structure, iii. 472, '. . . Halley — diameter of the annual orbit, iii. 633, Note — opinions respecting its figure, iv. 651, Cassini — advantage of, over other planets, for astronomical dis- coveries, v. 1 5, Gregory — dissertation on the figure of, vii. 60, 99, . . Desaguliers — the figure of, viii. 20, Stirling -— investigation of the figure of, viii. 119, Clairaut — proposal for measuring, in Russia ; various inquiries into the figure of, viii. 124, De lisle Earth, actual admeasurement of the basis, viii. 134, . . Same — enquiries concerning the figure of, viii. 413 — a place in New York for ascertaining the figure of, viii. 419> Alexander — gradual approach of, to the sun, ix. 684, Euler — form and magnitude of the, x. 307, Frisi — M. Clairaut's defence of his theory, x. 328 — on the figure of, and irregularities of surface, x. 709, Condamine — nutation of the axis of, xi. 19, Walmesley — theory of the irregularities of its motion, xi. 31,. . Same — horary alteration of the equator, xi. 170, Simpson — on the variation of its diurnal motion, xi.305, Walmesley — of its mean density, xiii. 719, Maskelyne — its mean density deduced from calculations of a survey of the hill Schihallien, xiv. 408, Hutton — experts, to determine its density, xviii. 388, Cavendish Earth (mineralogy,) a blue substance found in peat moss, xii. 547, Douglas — strata of a well at Boston, xvi. 1 83, Limbrid — a substance found in a clay pit, xviii. 421, . . Wiseman Earths (chemistry,) analysis of calcareous earth, xv. 243, Kirwan muriatic earth, xv. 244, Same argillaceous earth, ibid, Same — method of trying the fusibility of, xvi. 671, Note, Wedgwood — analysis of terra australis, xvi. 667, Wedgwood xviii. 296, Hatchett Earthen-ware, gold-coloured glazing for, viii. 606, Heinsius Earthquakes, (in general,) remarks on, ii. 658, Pigott — caused by pyrites, iii. 16, Lister — cause of, iii. 555, Hartop — the sources of rivers in Batavia stopped up by, iv. 502 — opinion on the cause of, vii. 182, Derham x. 100, 1 15, Stukely x. 109, Hales — curious appearance accompanying, x. 114, Seddon ibid, Doddridge on the cause of, xi. 245, Peyssonel - xi. 448, Michell — a method of ascertaining the direction and strength of, xii. 190, Chandler — remarks on the cause of, xvii. 220, Tumor Earthquakes (particular,) an earthquake, near Oxford, i. 59, Wallis; i. 60, Boyle — particulars of some late earthquakes, i. 463 — near Oxford, 1683, ii. 658, Pigott — in Sicily, 1693, iii. 555, Hartop 556, iii. 602, Bonajutus — in Peru, 1687 5 in Jamaica, 1688, 1692, iii. 624, Sloane — in the North of England, ] 703, v. 104, Thoresby — in New Englahd, account of, vi. 87, Mather — in Sicily, 1693-4, 1717, vii. 46, Bottoni — in Kent, August, 1727, vii. 195, Barrel — at Boston, October, 1727, vii. 348, Colman — in Naples, March, 1731, vii. 606, Cyrillus — in America, 1732, vii. 6l4, Lewis — of several in New England, viii. 22, Dudley — in Sussex, October, 1734, viii. 96 . . . Duke of Richmond — of die same, ibid, Bayley — in Northamptonshire, October, 1731, viii. 98, . . . Wasse — at Naples, 1732, viii. 401, Temple — at Scarborough, 1737, viii. 514, Johnson — in New England, 1727, 1741, viii. 552, Plant — at Leghorn, 1742, viii. 568, ... Pedini £ AS INDEX. EHR 37 Earthquakes, (particular) in Somerset., 1747, ix. 533 Forster — of several in 1747, 1749, 17^0, communicated by a va- riety of persons from different parts of England, x. 108 — at York, 1754, x. 469, Baker — at Constantinople, 1754, x 548, Mackenzie — in the lead mines, Derby. Nov., 1, 1755, x. 656, Bullock — at Lisbon, ibid, . . Wolfall 1 x. 659, Saccheti — Zsu-queira, — — — ibid, . . Lathan — Colares, — Oporto, ■ — Madrid, — Cadiz, - x. 660, Stoqueler x. 661, x. 662, -. ibid, . . Bewick ibid, . . D'Ulloa — various parts of Barbary, x. 66'3, Lord Royston Madeira, x. 664, Heberden » . — — — x. 665, Chambers — Switzerland, Nov., 1, andDec, 9, 1755, ibid, Vautravers — Geneva, Dec. 9, 1755, x. 666, Trembley — Boston, America, Nov., 18, 1755, ibid Hyde — New York, x. 667, Colden — Pennsylvania, ibid, Collinson — Glasgow, Dec. 1755, x. 6*87, Whytt — Geneva, Nov. 1755 ibid, . Bonnet — in Flanders, Dec. 1755, x. 687, Allemand — the Hague, Feb. 1756, x. 696, Grovestins — Holland, ibid Allemand — Brussels, Dec, 1755, and Feb., 1756, ibid Pringle — in England, Feb., 1756, x. 703, Warren — Turin, 1755, 1756, x. 707, Donati — Brigue, several in continuance, ibid. — Maestricht, 1756, xi. 8 Vernede — Cologn, Leige, &c. 1 756, xi. 56, Trembley — New England, 1755, xi. 6l, Winthrop — Sumatra, 1756, xi. 192, Perry — in Cornwall, 1757, xi. 196, Borlase — in Surry, 1758, xi. 235, Burrow — several in Syria, xi. 437, Russell — Lisbon, l?6l, xi. 541, ibid Molloy — Madeira, 1761, xi. 543, Heberden — in Siberia, 1761, xii. 3, Weymarn — in the East Indies, 1762, xii. 12, 13, Gulston xii. 12, Hirst xii. 13, — at Lisbon, 1764, xii. 189 — Macao, 1767, xii. 607, De Visme — Manchester, 1777, xiv. 330, Henry — of several felt in Wales, xv. 85, Pennant — near Denbigh, 1781, xv. 115, Lloyd — in Wales, 1782, xv. 353, Same — in Italy, 1783, xv. 373, Hamilton — Calabria, 1783, xv. 383, Ippolito — the North of England, 1786, xvi. 176, More — Lincolnshire, 1792, xvii. 220, Tumor — England, 1795, xviii. 31, Gray — see Waters {Agitation of.) Easter, explanation of the rubrics for the seat of, iv. 273, Wallis — rules for finding, v. 202, Thornton — explanation of the rule for finding, v. 250, Jackman — method of finding, x. 37, Earl of Macclesfield East Indies, answers to queries respecting pearl divers ; oil of cinnamon ; lignum aloes j cobra capella, &c. i. 307, Vernati — account of Malabar, Coromandel, Ceylon, &c. i. 688, Baldaeus Ebn, Younes, translation of a passage in, xiv. 133, Costard Echoes, on the doctrine of, v. 394, Derham — account of extraordinary, ix. 253, Southwell Echinites, a curious specimen of, ix. 326, Baker — two beautiful specimens, ix. 665, Da Costa — remarks on a petrified echinus, x. 594, Parsons — of an echinus from the isle of Bourbon, x. 628, Brander Eclipses, of the eclipse foretold by Thales, x. 310, Costard — an eclipse mentioned by Xenophon, x. 356, .... Same — eclipse foretold by Thales, x. 380, Stukely — see Sun, Moon, Jupiter's Satellites, &c. Ecliptic, obliquity of, iii. 75; Bernard, 78 Note — obliquity unaltered, iii. 407, Wurtzelbaur — diminution of the obliquity of, xiii. 387» .... Hornsby Eden river, remarkable deer, of its water, xi. 679, Milbourne Edens, J., journey to the peak cf Teneriffe, vi. 177 Edgeworth, Rich., Lovell, expts. on the resist, of air, xv. 362 — observation of a meteor, August, 1783, xv. 481 Edinburg, heat of, compared with that of London, xiii. 685, Roebuck Edwards, George, biographical account of, x. 450, . . Note — of the pheasant of Pennsylvania, [tetrao umbellus] ibid — of the otis minor [otis tetrax] x. 452 — of the lacerta gangetica, x. 712 — new species of snipe [tringa lobata] xi. 130 — of a solar iris seen after sun-set, xi. 137 — of the frog-fish of Surinam [rana paradoxa] xi. 474 — of a bird supposed between a turkey andapheasant,xi. 493 — an observation in optics, xii. 4 — description of a Chinese pheasant, xii. 202 the vultur serpentarius, xiii. 93 Eels, micros, ob&ervs. of the scales of, iii. 125, Leuwenhoek — on the generation of, iv. 94, Same iv. 199, Allen . iv. 244, Dale on the circulation of blood in, v. 530, .... Leuwenhoek on the mouths of eels in vinegar, viii. 674, Miles — of paste, viviparous, ix. 202, Sherwood — on their perpendicular ascent from water, ix. 3 11, Arderon Eeles, Henry, on the cause of thunder, x. 287 — on the ascent of vapour, x. 587 ; cause of winds, 589 > phenomena of the weather, 591 Effervescence, produced by mixing two cold liquors, iii. 664, Slare — nature and cause of, ix. 680, Le Cat — see Fermentation. Effluvia, noxiousness of putrid marshes, xiii. 502,. . Priestley — effects of, on the air, xiv. 322, White — see Electricity, Gas. Eft, water eft slipping off its skin, ix. 349, Baker — see Lacerta aquatica. Egg, method of keeping birds taken from the, i. 66, . . Boyle — observ. of eggs in females of all sorts, i. 697, Kerkrin^ius — of an egg as large as a duck's, in testiculo mulieris, i. 702 — progress of the formation of the chick in, ii. 13, 232, Malpighi — ■ an egg in the fallopian tube on dissection, iii. 605, Bussiere — an egg within an egg, iv. 183, Vallemont — in females, non-existence of proved by Buffon, ix. 607 Needham — progress of the ova to the fallopian tubes and uterus xviii. 129, Cruikshanks EgyPr> observations in upper Egypt, i. 591, Brothai — description of, i. 595, Vanslebio — early proficiency in medicine, ii. 208 Ehm, — , m.d. of St. George's bath near Landeck, v. 333 Ehrhart, Balthasar, m. d., biograph. notice of, viii. 451, Note 38 ELE d., geological account of the Tyro- INDEX. ELE Ehrhart, Balthasar, m lese Alps, ibid. . m Ehret, Geo. Dionysius, descrip. oftheophrys lilifoha, xi. 7"i — of the nolana prostrata, xi. 70S — of the arbutus andrachne, xii. 403 ... Eimart, G. C., magnetical variation at Nuremberg, hi 244 _ lunar ec'ipse, November, 1685, Nuremberg, ut. 318 Elasticity, thoughts on the cause of, viii. 340, Desagu ers — theory of the action of springs, ix. 18,. . • • • JUI1" — see Air, Motion, (Force of moving Bodies) Elden Hole, Derbyshire, account of, xiii. 137, LAoya _ xiii. 140, J^mg Elder, effect of, in preserv. plants from flies, xiii. 319 Gullet Ele Martin, coal, traded from a stratum of of pitch oil, &c. ex iv. 168 Electricity, attract, of resins by certain stones, u. 181, Lister — catalogue of electrical bodies, iv. 323, • • rwtt — production of light by attrition of glass, v. 307, 324, — of sealing-wax, v. 452, • • • Sa™e — . electrical experiments, vi. 492, vii. 449, 513, 539, sou, viii. 2, 51, 110, **ra>' — catalogue of electrical bodies, vii. 539, • • baine — electrical discoveries, vii. 638, • Du *ay — motion of pendulous bodies by, viii. 05, . ; . • • • ^ray — exper. on the repulsive force of bodies, vm. 306,Wheeler — exper by Mr .Wheeler before the R.s.,viii. 313,Mortimer — on the circular exper. by Mr. Gray, viii. 3l6, Wheeler — electrical experiments, viii. 350—353, 357, 470, 472, 473, 479, 546, Desagul.ers — considerations respecting, viii. 584-, Same — experiments in, ix. 74, 109, Winkler — experiments on electric fire, ix. 94, Hollman the firing of phosphorus by, ix. 107. Miles — electrical phenomena, ix. 127, De Bozes luminous emanations from living bodies, ix. 136, Miles — exper .and observ. on, ix.151, 195, 408,410, 440, Watson of sealing-wax and brimstone, ix. 191, Miles — experiments in, ix. 198, 233, . .' Same — light from quicksilver in a glass tube, ix. 199, Trembley — nature of electric fire, ix. 207, Miles — of water, experiment on, ix. 213,. Same — to ascertain the strength of electrical effluvia, ix. 215 — experiment on himself and wife, ix. 251, ... . Winkler — of glass, affecting the magnetic needle, ix. 262, Robins — exper. at Paris by M. Le Monnier, ix. 262, . . Needham — on the communication of, ix. 275, Le Monnier — effect of, on vegetables, ix. 306, Browning — communication of, to non-electrics, ix. 308, . . Watson — of flannel, ix. 337, 532, Cook — description of a pvrorganon, ix. 345, Winkler — velocity of, &c, ix. 440, Watson — effect of, on animal and vegetable bodies, ix. 473, Nollet — experiments to discover the laws of, ix. 475, .... Ellicot — a fustian frock set on fire by, ix. 512, Roche — experiments in, ix. 534, Hales — experiments to ascertain the velocity of, ix. 553,Watson — possibility of odours pervading glass by, x. 13, . . Same — on the experiment of beatification, ibid, Same — various experiments made in Italy, x. 20, Nollet — nature and effects of, x. 189, Franklin — permeability of odours through glass, x. 197, • • Winkler — observations on the uses of, x. 227, Bohadsch — in vacuo, experiments on, x. 233, Watson — application of to the atmosphere, x. 238, Note — analogy of with thunder, exper. at Paris, x. 289, Mazeas Electricity, to extract from the clouds, x. 295, .'. . . Nollet exper. of collecting in a thunder storm, x. 298,. . Milius description of the electrical kite, x. 301, Franklin English experiments on thunderclouds, x. 302, Watson letters by the Abbe Nollet on, x. 372, xi. 580, . . Same — experiments made at Paris, x. 420, Wilson on thunder clouds, x. 421, 532,. . . . Canton — of the air, observations, x. 434, Mazeas on the luminousness of, in the clouds, x. 446, . . Birch experiments with the electrical kite, x. 522, Lining death of Professor Richman, occasioned by, x. 523, Watson j further account of his death, x. 574, experiments for artificial thunder, x. 529, Winkler ascent of vapour, winds, phenomena of weather, as- signed to, x. 5S7, Eeles experiments at Philadelphia, x. 629, Franklin — remarks on, x. 632, Same retractation of a former opinion of the Leyden exper., xi. 15, Wilson exper. on bodies which resist it, xi. 334, 589,. . Delaval electrical experiments on the tourmalin, xi. 396, Wilson of various bodies, experiments on, xi. 405, Symmer experiments of electrical cohesion, xi. 410, Same of two distinct powers in, xi. 413, Same force of electrical cohesion, xi. 418, Mitchell explanation of exper. by Beccaria, xi. 435, Franklin electrical experiments, xi. 504, Wilson on the electricity of water, xi. 506, Bergman of gems similar to the tourmalin for electrical experi- ments, xi. 606, •♦. Wilson remarks on experiments by Mr. Delaval, xi. 609, Canton — method of preserv. ships from lightning, xi. 660, Watson — electrical experiments, xi. 702, Kinnersley experiments on crystal, xi. 705, . . . . Bergman electric nature of the tourmalin, xii. 343, Same an improved apparatus for exper. in, xii. 4l6, L'Epinasse of rings of prismatic colours caused by electrical explo- sions on metallic surfaces, xii. 510, Priestley lateral force of explosions, xii. 600. Same exper. on the force of explosions, xii. 603, Same investigation of the lateral explosion, xiii. 36, ... . Same some phenomena of, ascribed to an elastic fluid, xiii. 223, Cavendish of the atmosphere, experiments on, xiii. 310, Ronayne; remarks on the same by Mr. Henley, 313 exper. with Henley's electrometer, xiii. 323, . . Priestley electrical powers of charcoal, xiii. 370, Kinnersley — of a cat's back, hair of the head, &c. xii. 4l6, Brydone improvement in the electrical machine, xiii. 456, Nooth description of his electrical machine, xiii. 498, Nairnej experiments made with it, 500 various electrical experiments, xiii. 551, Henley peculiar state of the atmosphere, xiv. 60, Cavallo Adams's machine for perpetual electricity, xiv.97, Henley — experiments in, xiv. 314, 571, Swift USe of an amalgam of zinc for electrical excitations, xiv. 446, Higgins — experiments with the electrophorus, xiv. 463, Ingenhouz — impermeability of glass to the electric fluid, xiv 4? 3, r Henley — improvements in machines, &c. xiv. 598, . . Ingenhouz — effect of, in shortening wire, xiv. 689, xv. 389, . . Nairne — method of rendering sensible weak electricity, xv. 263, Volta — non-conducting power of a vacuum, xv. 699, . . Morgan experiments with a new electrometer, xvi. 174, Bennet — of different electrometers, xvi. 354, Cavallo ELL INDEX. EPI 39 Electricity, on electrifying of glass, xvi. 407, Gray — of an instrument for collecting it, xvi. 449, • • • • Cavallo — conversion of airs into nitrous acid by, xvi. 451, Cavendish — an electric machine without friction, xvi. 505, Nicholson — experiments and observations in, xvi. 599> Same — journal of atmospheric, and instru., xvii. 52, 207, Read — observ. with his doubler of electricity, xvii 422,. . Same — method of producing air from water by electrical dis- charges, xviii. 104, Pearson — its effects on muriatic acid gas, xviii. 642, Henry — for other papers of Dr. Franklin see Lightning. — see also Electrometer, Glass, Attrition, Phosphorus, Gal- vanism, Conductors. — also Gymnotus Elect rictus, Torredo, Tetrodon Elect rietis. Electricity (Medical) a discovery in, ix. 494, .... Winkler — experiments in, ix. 497, ? Baker — diseases in which it is useful, x. 229, Bohadsch — account of Bianchini's treatise on, x. 242, .... Watson — experiments in the hospital at Shrewsbury, x, 534, Hart — cure of a paralytic arm by, x, 701, Same — cure of palsy by, xi. 163, 26*2, Brydone — efficacy in paralytic cases, x. 189, Franklin — case of palsy cured by, xi. 372, Himsel — effect of, applied to a tetanus, xi. 679, Watson — locked jaw and palsy cured by, xii, 391, Spry — cure of muscular contraction by, xiv. 302, . . Partington — cure of St. Vitus's dance by, xiv. 476, Fothergill — see Galvanism. Electrometer, a new one invented by Mr. Lane, xii. 475 — account of Mr. Wm. Henley's, xiii. 323, .... Priestley — on a new construction, xv. 308, Brook xvi. 173, 176, Bennet Electrophorus, experiments with the, xiv. 463, Ingenhousz — on Dr. Ingenhousz's theory of the, xiv. 473, . . Henley Elephants, docility of, i. 689; method of taking, i. 690 — manner of taking and taming in Ceylon, iv. 641, Strachan — nat. hist, and economy of, v. 557, vi. 382, Blair — dissection, and admeasurem. of the bones, v. 560, Same — contexture of the skin of, v. 6£)9> Leuwenhoek of the organ of hearing in, vi. 382, Blair — habits, manners, and natural history of, xviii. 444, Corse . — different species of Asiatic elephants, and mode of den- tition, xviii. 509, Same — on the structure of their teeth, xviii. 519, Home — see Mammoth, Bones. Elk, anatomical observations on the, ii. 292 Ellicot, Mr., observations at St. Helena on the going of his clock, xi. 630, Mason Ellicot, J., to-measure the expansion of heated metals, viii. 82 — influence of pendulum clocks on each other, viii. 320, 322 — specific gravity of diamonds, ix. 147 — experiments to discover the laws of electricity, ix. 475 — height of the ascent of rockets, x. 96 — irregularity of a pendulum arising from temperature, contrivances for preventing, x. 271 Elliot, J., m. d., affinities of substances in spirit of wine, xvi. 79 Ellipse, theorem on the, xii. 222, Waring Ellis, Rev. Charles, invention of printing, &c, v. 50 Ellis, Henry, on Dr: Hales's ventilators, x. 195 — Dr. Hales's bucket for examining the temperature and saltness of the sea, x. 196 — heat of the weather at Georgia, xi. 277 Ellis, John, observ- on a remakable coralline, x. 345 — description of a salt-water cluster polype, x. 409 — - different sorts of corallines described, x. 453 — animal nature of corallines, &c, x. 490 Ellis, John, remarks on a specimen of alcyonium, x. 671 — of the tree yielding the Chinese varnish, xi. 46, xi. 181 — of a red coral (isis ochracea) from the East Indies, xi. 109^ — reply to Dr. Baster in support of the animal nature of corallines, xi. 134 — description of some rare species of barnacles, xi. 307 — experiments on the preservation of seeds, xi. 373 — of the plants halesia and gardenia, xi. 50S — description of a star-fish (isis asteria), xi. 591 • the cochineal insect (coccus cacti), xi. 674 the sea-pen (pennatula phosphorea), xii. 41 — nature and formation of sponges, xii. 257 — description of the siren lacertina, xii. 322 the horned viper of Egypt, xii. 355 — animal nature of zoophyta, xii. 458 — nature of the actinia sociata, xii. 468 — method of preserving acorns for planting, xii. 514 — increase of animalcula in vegetable infusions, xii. 6l2 — indissoluble salt from an infusion of hemp-seed, xii. 616 — descrip. of the leblolly-bay (gordonia lasianthus), xiii. 84 starry anniseed-tree (illicium floridanum), xiii. 85 — animal nature of the gorgonia, xiii. 720 Elms, propagation of from seed, iii. 599, Bulkeley Ellstobb, Wm., Jun., lunar eclipse, Dec. 1749, ix. 699 Elsholt, Dr., notice of useful experiments by, ii. 522 Elton, J., quadrant for altitudes without a horizon, vii. 531 Embanking, utility of furze for dam-heads, &c, xi. 514, Wark Embryo, see Talus. Emery, formation of the emery stone, xii. 341, ..Bowles Emeticks, for ages and constitutions, v. 255, 399, Cockburn Empyema, case of the operation for, x. 244, Warner — another case, x. 394 Same Emulgent vein, discovery of a communication with the thoracic duct, i. 163, 736, Pecquet} remarks on, by Needham, i. 736 Emulgents, extraordinary conformation of, ii. 448, . . Tyson Encaustic painting, see Painting. Encrinus, see Star Fish. Engine, for grinding hyperbolic optic glasses, i. 396, Wren — for weaving without an artificer, ii. 439, De Gennes — for consuming smoke, iii. 292, Justel — Mr. Savery's, for raising water by fire, iv. 398 — for drawing foul air from mines, vii. 208, . . Desaguliers — on the greatest effect of engines, xi. 317, Blake — to diminish the friction in engines, xi. 709, Fitzgerald — for pile driving improved, xiv. 498, Bugge — see Machines, Instruments, Steam Engine, Hydraulics. Engines, on the greatest effect of, xi. 317, ........ Blake England, number of acres of land in, v. 620, Grew — remarks on the probable existence, formerly, of an isth- mus joining England and France, iv. 6l8, 637, Wallis — inquiry on the same subject, vi. 293, Musgrave Englefield, Sir. H. C, appearance of the soil on opening a well at Han by, xv. 117 — variation of light in the star Algol, xv. 460 Ent, Sir George, m. d., biograph. acconnt of, ii. 471, Note — discovery of tempers from the voice, ii. 441 — various anatomical observations, ii. 471 — weight of a tortoise at retiring into the ground, and at re-appearing in the spring, iii. 458 Epact, remarks on the, x. 35, Earl of Macclesfield Ephemera, see May-fly. Epicycloid, quadrature of a portion of the, iv. 40, Casswell Epidemic diseases, account of, and obser., iii. 364, Molyneux — a severe epidemic at Barbadoes, xi. 6 15, Mason Epilepsy, case of, iii. 198, , Cole 40 EVE INDEX. EYE. Epilepsy, some unusual fits of, iv. 6*79, Leigh — seat and cause of, v. 73, Cole — remarks on the brain in cases of, vii. 199* • • • • Rhaetus Epinasse, C. Le (see L'Epinasse) Epiploon, observations on, i. 202, Malpighi Epsom Salt, experiments on, vi. 662, Brown Equations, resolution of, in numbers, i. 338, Collins — construction of solid problems, iii. 376, Halley — on the roots of cubic and biquadratic, iii. 395, . . Same — method of finding the roots generally, iii. 640, .... Same — to extract the root of an infinite, iv. 275, .... Demoivre — resolution of cubic and biquadratic, v. 334, .... Colson — of the 3d, 5th, 7th, &c. degree, v. 342, . . Demoivre — extraction of numeral roots of, vi. 299* Taylor — with impossible roots, vii. 145, Maclaurin — of goniometrical lines, ix. 357, Jones — machine for finding the roots of, xiii. 48, .... Rowning — on the limits of, xiv. 382, Milner — extension of Cardan's rule, xiv. 453, 624, .... Maseres — resolution of algebraic equations, xiv. 487* .... Waring — first invention of Cardan's rule, xiv. 672, Maseres — on the roots of, xv. 86, Earl Stanhope — usefulness of sines and tangents in the resolution of, xv. 139, Wales — on the equal roots of equations, xv. 317* Hellins — properties of the sum of divisors, xvi. 497* .... Waring — method of corresponding values, xvi. 563, Same — on the roots of, xviii. 341, Wood — resolution of algebraic equations, xviii. 529, • • • • Wilson Equation of Time, method of comput. xii. 163, Maskelyne Equator, horary alteration of the Earth's from the attraction of the sun and moon, xi. 170, Simpson Equatorial Telescope, description and use of, ix. 695, Short — a new equatorial portable observatory, xiii. 104, Nairne — apparatus for correcting errors from refraction, xiv. 524, Dollond — description of his instrument, xvii, 304, .... Shuckburgh Equilibrium, see Balance. Equinoxes, on the precession of the, x. 436, .... Silvabelle -~— ■ xi. 19, .... Walmsley • xiv. 576, .... Milner, xvi. 303, Vince Equuleus of the ancients, account of, vii. 381* .... Ward Eratosthenes, the sieve of, xiii. 314, Horsley Ergot, various observations on, and of other diseases arising from the use of bad corn, xii. 209, Tissot — see Rye. Ermine, [mustela erminea] descrip. of xiii. 327* Forster Eskimaux Indians, manners and disposit. of, xiii. 22, Wales Essay Instrument, for specific gravities, ii. 215, .... Boyle Estancel, Val., observ. of comet of 1668, atBrasil, ii. 135 Ether, experiments with, vii. 394, 594, Frobenius — collection of Frobenius's papers respecting it, viii. 536 — method of making by distillation, xii. 491 Etmuller, Mich., m. d., biograph. account of, iii. 209, Note Etna, see Mtna. Ettrick, Henry, machine for reduc. femoral fract. viii. 454 Etruscan (see Coin, Inscription). Evaporation, to calculate the quantity of, iii. 387* . . Halley — observations on, iii. 658, Same — physical observations on, xii. 225, Franklin — considered as a test of dryness, xiv. 137, Dobson — tables of, at Liverpool for 1772 to 5, xiv. 139, • • Same — on the nature of, xvii. 259, De Luc Evatt, Rev. Sam., remark, monument in Derbyshire, xi. 632 Evelyn, John, biographical account of, i. 280, Note — representations of nature in wax, i. 37 Evelyn, John, maps sculptured in ba9- relief, i. 3f — a Spanish drill plough, i. 457 — effect of the winter of 1683 on his gardens, iii. 28 — scheme of the human arteries and veins, iv. 680 Evelyn, Sir G. A. W. Shuckburgh, see Shuckburgh. Euclid, way of demonstrating some propos. of, iii. 64, Ash Eudiometer, of a new one., xv. 355, Cavendish Eudiometry, see Air. Euler, Leonard, biographical account of, ix. 320, . . . Note — Russian discoveries on the N. E. coast of Asia' ibid — earth's gradual approach to the sun, ix. 684 — on the contraction of the planets' orbits, x. 16 — motion of the moon's apogee, x. 203 — reply to the remarks of Mr. Short and Mr. Dollond on his theorem of the abberrations of object-glasses x. 403, 404 Euler, — jun., sun's parallax from observations of the transit of Venus, 1769, xiii. 284 Euphorbium, case of a lady who swallowed 2 oz. of, xi. 476, Willis Eure, see Aqueduct. Euripus, irregular flux and reflux of the, i. 592, . . . Babin Excentricity, see Planets. Excise, on spirituous liquors, best method of proportioning it, xvi. 675, xvii. 263, Blagden ; appendix to the re- port, xvii. 272, Gilpin Excrescence, extirpation of, from the womb, x. 71, Burton Excretory ducts, discovery of two glands and ducts in hu- man bodies, iv. 445, Cowper — discovery of, from the glandula renalis, vii. 55, Valsalva — remarks on Valsalva's discovery, vii. 84, Ranby Exhalation, a fiery and infectious, in Pembrokeshire, iii. 6lS, Floyd Merionethshire, iii. 6l8, . . Llhyd Exoccetus volitans (flying fish) description of, xiv. 423, Brown Exostosis, on a boy's back, viii. 413, Freke Expansion, of heated metals, machine for measuring, viii. 82, Ellicot — comparison of, in different heated metals, x. 274, Same — tables of, and a new pyrometer, x. 482, 486, . . Smeaton — of fluids, experts, with two instruments, xvii.272, Gilpin — see Thermometer, Pyrometer. Explosion in the air, vii. 6*14, Lewis ! observed at Halsted, viii. 383 . . Vievar Springfield, viii. 384, Shepheard — see Meteor. Eye, the eyes united in a monstrous head, i. 29, .... Boyle — of a blemish in a horse's eye. i. 2l6, Lower — diseases of the, iii. 81, Tuberville — on the crystalline humour of, iii. 91* Leuwenhoek — two cases of disordered, iii. 109, Tuberville — on incisions of the cornea, v. 507, Gandolphe — dissection of, with the cataract, vii. 45 — observs. onrecov. of sight after 13 years, vii. 235, Cheselden — instruments for operations on the, vii. 237, Same ; viii. 528, Cleland — an extraordinary tumour of the eye, vii. 572, .... Klein — a wound in the cornea cured, viii. 324, Baker — cure of a tumour about the, ix. 83, Hope — cure of a wound of the cornea and uvea, ix. 535, . . Aery — cureofawound occasioned by a piece of lath, ix. 566, Hassel — method of opening the cornea, x. 357, 414, .... Sharp — case of a morbid eye, x. 56*1, Spry — extraordinary disease of the, xi. 274, Layard — on the eye of the monoculus polyphemus, xv. 322, Andre — on the contract. & dilatation of the pupil, xvii. 403, Hosack FAY INDEX. FIR 41 Eye,structure and action of the extern, muscles, xvii. 409, Same — nature and use of the muscles of, xvii. 453, 660, Home — structure of the eyes of birds, xvii. 557, Smith — on the morbid actions of the straight muscles and cornea, xviii. 74, Home — on the nature of the cornea, and its diseases, xviii. 82, Same — the gall offish efficaciousin diseases of, xviii. 86, .... Note — Mr. Soemmerings's discovery of an orifice in the retina, xviii. 326, Home — observations of an orifice in the retina, xviii. 327, . . Same — structure of the optic nerve, xviii. 431, Same -r- cause of the luminousness of the cat's eye, ibid, . . Same — see Vision, Sight, Cataract, Crystalline Humour. Eye-lids, an uncommon palsy in, viii. 225, Cantwell Faba, St. Ignatii (ignatia amara) medic, virtues of, iv. 356, Joannes further particulars, ibid Camelli ■ description of, iv. 442, Note Fabri, Honore, biographical notice of, i. 553, Note Fabritius, — m.d. of injecting medic, liquors into veins, i.205 Face, a blackness brought on by disease, v. 522, .... Yonge Facio, J. Chr., solar eclipse, May 12, 1706, Geneva, v. 296 Facio, Nic, on the solid of least resistance, vi. 48 Fage, M. La, see Lafage Faget, M., experiments with the French styptic, x. 298 Fahrenheit, Gabriel Daniel, biograph. account of, vii. i, Note — degrees of heat of boiling liquors, ibid — experiments of freezing in vacuo, vii. 22 — specific gravities of various bodies, vii. 32 — description of a new areometer, vii. 41 ■ ■■ barometer, vii. 54 Fairchild, Th., experts, on the motion of sap in trees, vii. 36 Fairfax, N., swallowing of toads, spiders, &c, innoxious, i. 144 — uncommonly large hail-stones, i. 168 — many stones cut from one bladder, i. 168 — dissection of a body dead of unusual diseases, 1, 199 — two anatomical observations, 1. 200 — peculiarities of nature in men and brutes, i. 200 — on a bullet voided with the urine, i. 286 Fairy-circles, remarks on, ii. 225, Jessop — accounted for by Dr. Withering, ibid, Note Falkland islands, account of, xiv. 1 Clayton Fallopian tubes, see Generation. Fantoni, Pio, evolution of a certain mechanical curve, xii. 446 Farina, of blossoms, effect of the commixture of, ix. 169, 599, 685, Cook ibid, Henchman — of the holly-hock & passion flower, ix. 230, 234,Badcock yew tree, ix. 243, Same i— see Plants. Farley, James, efficacy of quassia in fevers, xii. 5l6 Farr, Win., m. d., meteor, obs. at Plymouth, 1767, xii. 5^9 — - meteorological register at Plymouth, 1768, xii. 6l0 — meteorological journal at Bristol, 1774, xii. 6295 1775, xiv. 47: 1776, 179; 1778,593 Farringdon, Rev. W., description of the charr fish, x. 609 Fat, microsc. observ. on the particles of, vi. 5S3,Leuwenhoek — of an acid extracted from, xiv. 67 1, xv. 168, Crell — conversion of the flesh of a bird into, xvii. 192, . . Sneyd — conversion of animal muscle into, xvii. 389, 544, Gibbes Fauquier, Wm., extraordinary hail-storm in Virginia, xi. 273 Fawkener, Wm., on the production of ambergris, xvii. 6 Fawler, John, cure of sinuous ulcers in the arm, v. 378 Fay, M. Du, biographical account of, vii. 638, Note •r— electrical discoveries, ibid. Feet, of a boy turned inward when born, cured by sitting cross-legged, ix. 695, Milner Felton, Samuel, of a species of wasp of Jamaica, xii. 98 — description of the cicada rhombea, xii. 99 Ferguson, James, biographical account of, ix. 226, . . Note — phoenomena of the planet Venus, ibid. — improvement of the celestial globe, ix. 351 — machine for exhibiting solar eclipses, x. 456 — delineation of an expected transit of Venus, xi. 685 — description of the lophius, xi. 717 — projection of a solar eclipse, xii. 5 — a new crane with four different powers, xii. 86 — lunar eclipse, 1764, at Liverpool, xii. 113 — solar eclipse, 1764, at Liverpool, ibid. — description of a new hygrometer, xii. 151 — of the time in any number of lunations, &c. xii. 197 — method of constructing sun dials, xii. 454 Ferguson, John, excision of part of the spleen, viii. 263 Fermat, M. De, character of, i. 8 Fermentation, idea of the nature of, v. 491, Freind — of fermentations and solutions that may be called cold, iv. 6l 1, Geoffroy — see Effervescence. Fern, on the seed and seed-vessels of, v. 197, Leuwenhoek — description of the seed of, viii. 505, Miles Fern, , m. d., of an extra-uterine foetus, iv. 365 Ferner, Benedict, transit of Venus, 176l, xi. 562 — transit of Venus, solar eclipse, 1769, Stockholm, xii. 671 Ferns and Leighlin, Bishop of, doctrine of sounds, iii. 5 Feroe, remarks on the Islands of, ii. 246 Fevers, cause of the paroxysms of intermitting, iii. 509, Cole — nature and cure of, iv. 46, Pitcairn — use of cold wafer in, vii. 353, Cyrillus — disorder produced by checking the miliary fever, ix. 16, Camillis — of the jail-fever in Newgate, x. 318, Pringle — malignant, at Rouen, 1753-4, x. 567, Le Cat — instance of a remarkable recovery, xii. 551, Benvenuti — a periodical fever, and separation of the cuticle, xiii. 78, Latham — see Blister, Bark, Quassia. Fevry, Mon., of a monstrous double birth, vi. 66l Fibres, structure of the fibres of the intestines, ii.295,. . Cole — observations on the fibres of muscles, vi. 82, 502, 504, 576, Leuwenhoek — experiments on the irritability of, x. 613, . . Brocklesby Fidge, Wm., stone from the bladder of a dog, ix. 292 Field, Rev. Jam., two cases of wounds in the stomach, vi. 578 Fielding, R., m.d., extraction, of a bullet from the head, v. 489 Figures, cabalistic complications of, in India, iv. 540 — Phenician numerals used at Sidon, xi. 291, .... Swinton — see Arabian Figures, Date. Filtering stone, of the Mexican, viii. 30, Vater Finch, four species of fringilla from Hudson's Bay, xiii. 340, Forster Finlanders, some account of them, vii. 210, Kinck Fire, description of a water-bellows, i. 12 — nature of combustion, ii. 146, Mayo — proposal for checking the progress of, ix. 498, . . Hales — of the perpetual fire in Persia, ix. 503, Mounsey — mediod of securing buildings from, xiv. 447, Earl Stnnhope Fire (chemistry) produced by the contact of tin-foil with the salt of copper and nitrous acid, xii. 404, . . Higgins — increased weight of bodies by ignition, xiv. 97, Roebuck — see Effervescence. Fire (electricity) — see Electricity. 42 FLA INDEX. FLU Fire (subterraneous) eruption of, from the ground in Italy, iv. 320, , St. Clair — - of a subterraneous fire in Kent, vii. 195, Nesbitt — among the snows in Italy, cause of, x. 52, More — issuing from the earth in Dorsetshire, xi. 537, Stephens — cause of subterraneous fire, xi. 539, Same — from a rock, and a well, in India, xi. 600, Wood — see Damps. Fire-ball, see Meteor. Fire-engine, method of working ventilators in mines by, xi. 26b', Fitzgerald — see Steam-engine. • Fish, to catch by tickling, ii. 78, Templer — conjectures on the bladder of air in, ii. 211 — on the condensing or dilating of, in the water, ii. 212 — of poisonous fish at the Bahamas, ii. 213 — of several poisonous sorts, and their effects, ii. 213, Note — remarks on the swimming bladders of, ii. 218, .... Ray — of the rish yielding the purple dye, iii. 252, Cole — physiological remarks on, iii. 258, Willughby — on the interior structure of, iv. 138, Preston — of a shower of small fishes in Kent, iv. 302, .... Conny — necessity of air to fishes, v. 669, Hauksbee — duration of life out of water, vi. 46, Richardson — observ. on the muscular fibres of, vi. 523, Leuwenhoek — on the organ of hearing in, viii. 551, Klein — to prepare specimens of, viii. 559, Gronovius —way to keep them in glass jars, ix, 180, 322, 511, Arderon — easy method of catching fish, ix. 180, Same — on the power of hearing in, ix. 465, Same — of the fish called, in Russia, quab, ix. 470, .... Baker — on the power of hearing in, ix. 485, Brocklesby — effect of keeping roach in glass jars, ix. 511, . . Arderon — Mr. Tull's method of castrating, x. 554, Watson — four undescribed fishes from Aleppo, x. 667, .... Russel — of the Antilles which produce purple, xi. 227, Peyssonel — remarks on the fecundity of , xii. 441, Harmer — proportions in the quantity of spawn, xii. 444,. . . . Same — instances of sea fish living in fresh water, xiii. 154, Note Barring ton ■ — of a poisonous nature in the South sea, xiv. 108, Arderon — see Acipenser huso, Burbot, Cachelot, Carp, Chimoera, Chxtodon, Char-Jish, Cod, Cuttle-Jish, Exoccctus volitans, Frog-Jish, Gillaroo trout, Gurnard, Gwiniad, Gymnotus, Haddock, Jaculator, Limpet, Lophius, Ophidium, Pen- Jish, Perch, Physeter, Pike, Porpoise, Purple-fish, Prickle- back, Quab, Shark, Smelt, Soal, Star-Jish, Sturgeon, Sun-fish, Sword-Jish, Tetrodon, Torpedo, Trout, Unicorn- fish, Whale, Zeus. — see Shell-Jish. Fistula, a wound in the side, which became fistulous, vi. 480, Steigertball Fistula lachrymali*, operation of, viii. 17, Hunauld ■ a new treatment of, xiv. 679> « • Blizard Fits, see Epilepsy, Convulsions. Fitzgerald (Keane) application to the steam-engine of Dr. Hales's method of distillation, xi. 81, 157 — to work ventilators by the steam-engine, xi. 266 — description of a metalline thermometer, xi. 49 1 ! — on checking the luxuriant growth of fruit-trees, xi. 524 — new thermometer and barometer, xi. 543 — on lessening the quantity of friction in engines, xi. 709 — improvements in his wheel barometer, xiii. 17 — cultivation of Chinese hemp-seed, xv. 180 Fixed air, see Air. Flame, exper. on the transparency of, xvii. 373, Rumford Flamingo [phcenicopterus ruber] descr. of, vi. 268, Douglass Flamsteed, John, biographical account of, i. 414. . . Note — prediction of the celestial phenomena of 1670, i. 414 — appulses of the moon, i. 649, ii. 118 — appearances of Saturn in 1671, i. 660 — latitude and distance of the Pleiades, i. 673 — two observations of Jupiter, i. 706 — astronomical observations and predictions, ii. 5. — calculation of the parallax of Mars, ii. 34 — inclination of Jupiter to the ecliptic, ii, 65 — parallax of Mars, and of the sun, ii. 90 — place and motion of the moon, ii. 177 — new solar tables, ii. 178 — on Mr. Horrox's lunar system, ii. 220 — on the inequality of natural days, &c. ii. 236 — of spots in the sun, observed 1676, ii. 333 — observation at Greenwich of the comet of 1677, ii. 393 — on a corrected tide-table, ii. 555 — lunar eclipse, 1682, Greenwich, ii. 587; 1684, iii. 69 — conjunctions of Jupiter and Saturn, ii. 637 — eclipses and ingresses of Jupiter's satellites, 1683, ii. 660 — calculation of eclipses of Jupiter's satellites, 1684, ii.679 — eclipses of Jupiter's satellites predicted, 1685, iii. 89 — a new tide-table aud directions for, iii. 3 — of a spot in the sun, 1684, iii. 20 — solar eclipse July 1684, Greenwich, ibid ; 1706, v. 294 — his predictions verified of these eclipses, iii. 234 — instrument to find the distances of Jupiter's satellites from his axis, iii. 246 — eclipse of the moon, at Lisbon, 1685, iii. 336 Jupiter by the moon, 1686, iii. 336 — celestial observations at Greenwich, vi. 17, 168 — observs. of the accuracy of his tables, viii. i , Hodgson Flannel, on the electricity of, ix. 337, 532, Cook — usefulness of, as a dress, xvi. 260, , . . . . Rumford Fleming, Malcolm, m. d., nourishment of the foetus by the liquor amnii, x. 619. Fleas, on the generation of, iv. 348, Cestone — structure of the proboscis of, v. 316, .... Leuwenhoek — of the pulex penetrans of Brazil, ii. 434, Guattini Flesh, of a bird converted into fat, xvii. 192, Sneyd — on the conversion of into fat, xvii. 389, 544>. . . . Gibbes Flies, of a viviparous sort, i. 600, Lister — efficacy of elder in preserving plants from, xiii. 319, Gullet Floating bodies, on the theory of, xvii. 682, Atwood Florentine philosophers, of the Acad, del Cimento, iii. 87, Note Flowers, to preserve in winter, iv. 230, Southwell — observ. on the farina fcecundans of, ix. 230, 234, Badcock Flower, Mr., some unknown ancient characters, iii. 574 Floyd, Edw., description of locusts in Wales, iii. 6l7 — of fiery and infectious exhala. in Pembrokeshire, iii. 6l8 Floyer, Sir John, biographical account of, iv. 458,. . . . Note — of two monstrous pigs, and a double turkey, iv. 458 — to discover the properties of plants by the taste, iv. 676 Fluents, of multinomials, and converging series, ix, 513, Simpson — theorems useful in resolving, x. 469, ........ Landen — disquisition on certain fluents, xiii. 150, Same — method of finding, by continuation, xvi. 150,.. . Vince Fluid (Animal), existence of, in the nerves, vii. 550, Stuart — experiments on animal fluids in the exhausted receiver, xiii. 536, Darwin Fluids (Natural Philosophy) figures of contiguous surfaces, ii. 362, 372 Boyle — laws of the motion of, iii. 308, Mariotte — effect of heat and cold in the expansion, &c. of, iii. 505, Halley FON INDEX. FOS 43 Fluids, refractions and specific gravities of, v. 6l6, Hauksbee — resistance of, to falling bodies, vi. 506, . . . . Desaguliers — figure of revolving fluids, vii. 519, Maupertuis — experiments on the expansion of, xvii. 272, .... Gilpin — theory of the motion and resistance of, xvii. 466", xviii. 24S, Vince — see Steam, Water. Fluxions, use of in solving geomet. prob. iv. 14, Demoivre — account of the inventions of, vi. 1 l6, Newton — invention of the differential method, vi. 389, Conti ; Leibnitz's answer, vi. 390 — Maclaurin's account of his treatise on, 632, 667 — see Fluents. Fly, account of a viviparous fly, i. 600, iii. 46, .... Lister — account of the vegetable fly, xii. 15, Watson Fly-catcher, a species of, from Hudson's Bay, xiii. 341, Forster Flying, Bernier's machine for, ii. 476 1 — of a flying ship, ii. 478, Lana Flying-fish, see Exoaetus volitans. Focus, on finding the foci of optic glasses, iii. 593, Halley Foetus, particulars respecting the, human and brute, i. 117, Needham — on the gradual growth of, i. 413, 586, .... Kerckringius — on the formation of, i. 6lS — lying in the belly 26 years, ii. 435, Baley — necessity of respiration for, ii. 147, Mayo — an extra-uterine, iv. 110, Savaid — voided by the ulcerated navel, iv. 173, Brodie — voided above the os pubis, iv. 303 — lying without the womb, iv. 365, Fern — voided by the navel, iv. 631, Birbeck — way in which air is communicated to, iv. 708, . . Drake — bones of, voided through the groin, v. 246, .... Shipton — on the way of its receiving nourishment, v. 276, Brady - — instances of several extra-uterine, v. 52 1 , Yonge — bones of a fcetus from a cow, v. 532, Sherman — 46 years in the belly, case of, vi. 500, .... Steigerthall — of a sheep, micros, observations on, vi. 593, Leuwenhoek — an extra-uterine, 5 years in the body, vi, 666, Houstoun — bones of, voided per anum, vii. 53, Lindestolpe — preternatural delivery at the anus, vii. 432, .... Giffard — in the abdomen 9 years, viii. 488, Bromfield — bones of, voided per anum, ix. 108, Winthrop — an extra-uterine, ix. 1 12, Myddleton — voided per anum, ix. 170, Simon — 16 years in the abdomen, ix. 373, Myddleton — discharged near the navel, ix. 456, Drake — 13 years in the fallopian tube, ix. 460, Mounsey — extracted from the abdomen, x. 153, Debenham — in part nourished by the liquor amnii, x. 619, Fleming — with a very imperfect brain, xii. 405, Johnstone — produced with a live child, xiii. 79} Warner — see Monsters. Frogellius, lunar eclipse and solar spots, Hamburg, 1671, i. 659 Foley, S., d. d., of the giant's causeway in Ireland, iii. 606 Folkes, Martin, biographical account of, vi. 291,. . . . Note — aurora borealis seen at London, ibid — account of Mr. Leuwenhoek s microscopes bequeathed to the Royal Society, vi. 678 — standard Roman measures, viii. 74 — 3 parhelia seen in London, Sept. 1736, viii. 137 •i— experiments on the fresh water polypus, viii. 676 — bones incrusted with stone, ix. 181 — on a passage in Pliny, ix. 303 Fontana, Abbe, biographical account of, xiv. 526, Note *— on the poison of vipers, i. 58, Note Fontana, effects of inflammable air on animals, xiv. 526 — of the air, extracted from different waters, xiv. 563 — salubrity of the air at different places, xiv. 568 — experiments on the poison of the ticunas, xiv. 641 lauro-cerasus, xiv. 66l Food, men living in a mine 24 days without, iii. 32 — on the carnivorous nature of man, 551, 556, .... Wallis — remarks on the same subject in reply, iv. 552,. . . .Tyson — of a woman living 6 days under snow without, vi. 69, Bowditch — of a boy living 3 years without, vi. 459, Blair — extraordinary quantity eaten by a boy, ix. 124, . . . B — r — a woman who lived several years without, xiv. 121, Mackenzie — on the antiseptic regimen of the Russians, xiv. 395, Guthrie Foot (Measure) on the measure of the Roman, xi. 485,Raper — comparison of the English and French, xi. 487, . . Same — length of the Roman foot, xviii. 305, Note, Shuckburgh — see Measures. Foramen ovale, found open, in an adult, viii. 54, Amyand — in adults, remarks on, viii. 485, Le Cat Forbes, George, m.d., specimen of the limpet fish, xi. 313 Force, essay on the measure of, ix. 563, Miles — resolution of attractive powers, xvi. 572, Waring — see Centripetal Force, Motion, ( Force of moving bodies) Forceps, see Instruments, (Anatomical) Ford, James, successful use of agaric as a styptic, x. 579 Fordyce, George, M. d., biog. account of, xiv. 93, ..Note — of the light produced by inflammation, xiv. 93 — examination of various ores, xiv. 585 — method of assaying copper ores, xiv. 609 — loss of weight in bodies by heat, xvi. 13 — experiments on the nature of heat, xvi. 288 — on muscular motion, xvi. 36 1 — cause of the increased weight of metals calcined, xvii. 245 — account of a now pendulum, xvii. 336 Forehead, see Os Froniis. Forster, Rev. John, an earthquake at Taunton, ix. 533 Forster, John Reinhold, biog. account of, xii. 446, . . Note — Nat. Hist, of the country about the Wolga, ibid — of a new map of the river Wolga, xii. 556 — management of carp in Polish Prussia, xiii. 154 — of the dyeing roots found at Hudson's-bay, xiii. 282 — account of some quadrupeds from Hudson's-bay, xiii. 326 ■ birds ■— — xiii. 331 - fishes xiii. 410 — description of the tyger-cat of the Cape, xv. 1 Forster, Rev. Richard, bills of mortality of Great Shefford, 1747-57, xi. 157 — on the population of England, xi. 186 — a meteor, seen October 1759, in Berkshire, xi. 394 — bite of the slow- worm innoxious, xi. 614 Forster, Thomas, newly raised island near Tercera, vi. 584 Forth, Henry, observ. on the barometer in a storm, viii. 78 Fosse, M. La, exper. with lycoperdon as a styptic, x. 566 Fossils, opinion that shell-like fossils are stones sui generis, ii. 645, Lister — description of shell-like fossils, iii. 4, Hatley — tongue of an American marine animal dug up in Eng- land, iv. 200, Sloane — a figured fossil stones found in Wales, iv. 381,. . Lhwyd — found at Reculver Cliff, iv. 549, Gray — difference of, found in different soils, v. 123, . . Lhwyd — observ. of fossil shells of Switzerland, v. 1 69, Leuwenhoek — impression of an animal on a stone, vi. 398, . . Stukeley — a nondescript petrified insect found at Dudley, x. 105, Lyttleton F 2 44 FRI INDEX. GAL Fossils, further account of the same fossil, x. 106, Mortimer — description of a curious spheroidal stone, x. 107, Same — remarks on the Dudley fossil, x. 401, Da Costa — impression of a fish in a stone, x. 628, Byam j further particulars of the same stone, ibid, Pond — of coralloid fossil bodies, x. 688, Pennant — Donati's opinion respecting marine fossils found inland, xi. 84, Trembley — found at the Isle of Shepey, xi. l65, Parsons — curious stone near Christchurch, xiii. 418, . . Barrington — on the cause of fossil vegetables, &c. xviii. 481, De Serra — see Shells; Glossopetrx ; Belemnites ; Echinites; Nauti- lites; Orthoceratites ; Star-Stones. Fothergill, Anth., m. d., effects of the frost, 1776, xiv. 116 — St. Vitus's dance cured by electricity, xiv. 476 Fothergill, John, m. d., biographical account of, ix. 9, Note — on the origin of amber, ibid. — observations on manna, ix. 31 — recovery from suffoca. by distending the lungs, ix. 103 — rupture of the diaphragm in an infant, ix. 187 — account of Gmelin's Flora Sibirica, ix. 491 — account of Knight's magnetical machine, xiv. 117 Fouchy, J. P. G., on the lunar atmosphere, viii. 371 Fountains, see Springs. Fouquet, J.Fran. new Chinese table of chronology, vii. 427 Fowke, Gen., earthquake, Nov., 1755, in Barbary, x. 663 Fox, of the arctic fox, [canis lagopus,] xiii. 326, . . Forster Fracassati, Charles, injecting of liquors into the veins of animals, i. 170 — experiment on blood become cold, i. 172 Fractions, on infinitely infinite, ii. 502, Wood — on a passage in Girard on converging, x. 430, Simson — theorems for resolving fractions, x. 46*9, Landen Fracture, seeOsFemoris, Frontis, &c. ; MachinesChirurgical. Frankfort, births, deaths, &c. at, 1695, iv. 169, Slare Frankland, SirThos., the welding of cast steel, xvii. 572 Franklin, Benj., ll. d., biograph. account of, x. 189, Note — nature and effects of electricity, ibid. — electrical experiments on the effects of lightning, x. 212 — description of the electrical kite, x. 301 — electrical experiments at Philadelphia, x. 629 — observations on the nature of electricity, x. 632 — effects of electricity in paralytic cases, xi. 189 — explanation of electrical exper. by Beccaria, xi. 435 — letter respecting some electrical experiments, xi. 609 — an aurora borealis seen at London, 1757, xi. 6l4 — physical and meteorological observations, xii. 223 — on the stilling of waves by oil, xiii. 568 Franklin, J. observ. of a luminous arch, Feb., 1784, xvi. 631 Frantz, Father, observ. at Vienna, of a comet, 1743, viii. 681 Fraser, Rev. James, account of Loch-Ness, iv. 398 Fraxinus Sylvestris, [sorbus aucup.] an excellent liquor from the berry of, i. 305, Beale and Tonge Freeman, Wm., calculous concret. under the tongue, ix. 6l8 — description of Herculaneum, x. 166 Freezing, see Ice (artificial), Frost. Friend, John, m. d., biogrophical account of, iv. 423, Note — a hydrocephalus and dissection of the head, ibid. — of a remarkable kind of convulsion, iv. 564 Freke, John, exostosis on a boy's back, viii. 413 — machine for reducing a dislocated shoulder, viii. 706 Frewen,T., m.d., effects of the small-pox at Hastings,vii.480 — a stone voided through the perinceum, xi. 571 — case of a man stupified by sea-coal, xi. 608 Friction, medical effects of, i. 67, Oldenburg — of machines reduced to calculation, vii. 539, Desaguliers — of pulleys, experiments on, vii. 566, Same — in engines, to lessen the quantity of, xi. 709, Fitzgerald Friction, experiments of its effect on motion, xv. 654, Vince — on the source of heat excited by, xviii. 278, . . . Rumford Fright, the use of speech recovered by, ix. 465, Squire Frisi, Paul, biographical notice of, x. 305, Note — form and magnitude of the earth, ibid. Friuli, of the mines of mercury at, i. 10, p0pe Frobenius, Sig. Aug., m.d., experts, with ether, vii! 394 — experts, with ether, and phosphorus of urine, vii. 594 — collection of his papers on ether, viii. 586, . . .Mortimer Frogs, on the generation of, ii. 664, Leuwenhoek — remarks on the spawn of, Hi. 456, Waller Frog-fish [lophius piscatorius] descrip. of, ix. 658, Parsons — of Surinam [rana paradoxa] xi. 474, Edwards Froidour, M. De, on the canal of Languedoc, i. 723 Frost, effects of a remarkable frost, ii. 37 — observations on the above-mentioned, ii. 56, Wallis — effects of severe frost on trees, &c. iii. 89, Bobart — account of the great frost, 1708-9, v. 533, Derham — account of the frost in 1730-1, vii. 448, Same Feb., 1767, xii. 474, Watson — effects of the frost in Jan., 1776, xiv. 116, . . . Fothergill — comparative temperature of hoar-frost, and the air near it, xiv. 705 j xv. 129, Wilson — a remarkable frost, June 23d, 1783, xv. 604, . . Cullum — see Winter, Meteorological Observations. Fruit, to make grow in winter, and to preserve, iv. 230 Southwell — bad effect of swallowing stones of, iv. 710, . . Vaughan — see Cherries. Fruit-trees, to promote the fruitfulness of, i. 333, . . Tonge — to graft upon pieces of root, ii. 79, Lewis — to check the too luxuriant growth of, xi. 524, Fitzgerald — fruitfulness promoted by washing the stems, xiv. 124, xv. 138, Marsham — see Farina. Fuel, contrivance for saving, iv. 154, Papin Fuller, John, a storm of salt rain in Sussex, v. 91 — efficacy of Dampier's powder in the bite of a mad dog, viii. 204 — meteoric lights observed December 1737, viii. 46l — explosion of a fire-ball, viii. 540 — description of a large lake in Yorkshire, viii. 463 Fuller, Rose, m. d., comet of 1737, at Jamaica, viii. 154 Fuller, Steph , a hurricane in Huntingdonshire, viii. 530 Fuller's earth, pits of, in Bedfordshire, vi. 674, Holloway Fungus, of a subterraneous fungus, ii. 119, Lister — of the generation of fungi, vi. 195, Marsigli — poisonous nature of some fungi, ix. 43, Watson — a new species of, ix. 99, Martyn — account of Schaeffer's natural history of, xi. 6l5 — of the lycoperdon phalloides, xv. 607, .... Woodward — see Agaric, Lycoperdon, Mushrooms, Truffles. Furze, utility for making dam-heads, &c. xi. 514, . . Wark Fynney, Fielding Best, of a hard substance extracted from the coecum, xiv. 186 G Gabry, Peter, aurora borealis, 1750, x. 134 — observations of a comet, 1759, at the Hague, xi. 677 meteor, 1758, at the Hague, ibid Gaertner, Jos., m. n., of the urtica marina [actinia] xi. 525 Gailhard, M., observations on dissected bodies, iv. 207 Gale, Benj , m. d., of inoculation in America, xii. 229 — efficacy of salt in curing the bite of a rattlesnake, xii. 244 Gale, Roger, Roman inscription at Chichester, vi. 667 — Roman inscription near Lancaster, vi. 364 — remarks on an ancient chirograph, viii. 64 — vegetation of old melon seeds, ix. 100 GEL INDEX. GHI 45 Gale, of some human fossil bones, ibid Gall of fish efficacious in diseases of the eye, xviii. 86,Note — . of beasts and fish used by the Arabians in diseases of the eye, xviii. 87» ftussel Gall bee, account of the, iv. 319, Allen Gall-bladder, dropsical distention of, v. 66*7, Tonge — effects of a wound in, vii. 407, • • . Stuart — imposthumation of the, viii. 228, Amyandj observations on the same case, viii. 232, Stuart — of a body without a gall-bladder, ix. 649, Huber Gall stones, case of, ii. 449, . . . * Tyson — two uncommon cases of, xi. 21 1, Johnstone Gallet, M., solar eclipse 1676, at Avignon, ii. 444 Galvanism . amalgam of zinc for elect, excit xiv, 446,1 liggins — of some experts, by Galvani, xvii. 285, Volta — cause of muscular contraction in galvanic experi- ments, xvii. 548, Wells — new galvanic instrument, xviii. 744 Volta Galvez, Count de, on directing air-balloons, xv. 625 Gandolphe, — m. d., on incisions of the cornea, v. 507 Ganges, account of the river, xv. 39, Rennel Gangrene, case of the leg and part of the thigh destroyed by, v. 397, Calep — on the cure of dry gangrenes, ix. 643, Le Cat — see Mortification. Garcin, Laurence, m. d., of the oxyoides (oxalis) vii. 421 — of the family of plants named Musa, vii. 422 sea-leech, vii 424 — the mangostan tree [garcinia mangostana] vii. 631 — of the Cyprus tree of the ancients, ix. 583 — of the genus of plants, salvadora, ix. 636 Gard, Rev. Samuel, Du, see Dugard. Garden, remains of the Bp. of London's at Fulham, x. 200 Garden, Alex., M. d., of the gymnotus electricus, xiii. 600 Garden, George, m. n., of an imitative man, ii. 382 — of immense human calculi, ii 383 — theory of the weather and winds, iii. l62, 210 — modern theory of generation, iii. 431 — effect of a thunder storm at Aberdeen, iv. 109 — origin of the caterpillars that infest fruit-trees, iv. 233 — of a stone cut from a boy with a flint in it, iv. 525 Gardenia [cape jasmine] description of, xi. 509, ....Ellis . — — — xi. 669, Solander Gardening, setting of kernels, and sowing of seeds, ii. 192 — method of raising exotics in England, vii. 250, . . Miller — see Plants, Fruit-trees. Garsten. Christian Lewis, calculation of eclipses, &c. ix. 40 Garth, Samuel, m. d., biographical account of, v. 399, Note Garthshore, Max., m. d., cases of numerous births, xvi. 294 Gas, original use of the word, ii. 155, Note — experts, on hepatic air, [sulph. hydro, gas] xvi. 68, Kirwan xvi 286, Hassenfratz — of the gas produced by electrical discharges through water, xviii. 104, Pearson —experts, on carbonated hydrogen gas, xviii. 221, . . Henry — see Airs, {Chemistry .) Gascoigne, remarks on his micrometer, i. l6l, Townley; i. 195, Hook j x. 369, Bevis — inventor of telesc. sights for math, instru. vi. 295. Derham Gaubill, Father, astronomical observations at Pekin, x. 3 — Chinese knowledge of geography, x. 6 — of the paper money of China, x. 7 — two letters from China, x. 411, 412 — plan of the city of Pekin, x. 265 Gaze, J., convulsions cured by discharge of worms, xi. 203 Gazelle, anatomical description of the, i. 373 Geach, Francis, two remarkable surgical cases, xii. 4 Gellibrand, Henry, biographical notice of, i. 189, .... Note Generation, opinions on the parts of, i. 241, 271, De Graaf, and Van Home — remarks on, and on the doctrine of De Graaf, &c, i. 241, Clarck — of the ova in mulierum testibus, i. 617, 697 — on spontaneous generation, i. 617, Ray — modern doctrine of impregnation, i. 697, ii. 5S1, Notes — on the sterility of hybridous animals, ii. 289 — of the genitals of a rattlesnake, ii. 564 — theory of, ii. 580, 664, iii. 199, Leuwenhoek — of animals from eggs, and case of a bitch, with the ova affixed to the abdomen, ii. 6l5 — modern theory of, iii. 431, Garden — on the propagation of animals, iii. 525, Leuwenhoek — an egg in the fallopian tube, remarks on, iii. 605, Buissiere — objections to Leuwenhoek's hypothesis, iv. 310, . . Lister — reply to the above objections, iv. 412, Leuwenhoek — discovery of glands in the urethra with excretory ducts iv. 445, Cowper — remarks on the female parts of, v. 312, Marchetti — parts of, in a sheep, vi. 594, Leuwenhoek — preternatural structure of the parts in a woman, vi. 671 rvii- 4,2> Huxham — of the kanguroo, descripion of the organs and mode of xvii- f35> Home — extraordinary genitals in a boy, ix. 95, Almond — see Testicles, Semen, Va.sa dejerentia, Eggs, &c. — see Impregnation. Geneva, description of the lake of, ii. 6 — a convenient situation for measuring an arc of the meri- dian, xvii. 34, Pictet Genitals, see Generation. Gennes, M. De, a clock on an inclined plane, ii. 439 — machine for weaving without an artificer, ibid Geoffroy, Stephen Francis, biog. account of, iv. 336, Note — analysis of the mineral water of St. Amand, iv. 336 — two spirituous liquors, which, by mixture* produce a carnation colour, iv. 348 — regulations of the royal academy of Paris, iv. 374 — of solutions which may be called cold, iv. 6ll — of a new thermometer, iv. 616 — fusion of metals with a burning glass, v. 501 — account of Seignette's Rochelle salt, viii. 10 — soap-lees for medicinal uses, viii. 565 — a child of a monstrous size, viii. 727 — effects of vitrum antimonii ceratum, x. 207 Geography, scale for the calculation of, reduced from the rate of travelling by camels, xvii. 38, Rennell — see Maps. Geometry, solution of Alhazen's problem, ii. 97 — demonstrat. of a right line equal to a curve, ii. 112, Wall's — on geometrical demonstrations, iii. 64, Ash — solution of Viviani's problem, iii. 609, Gregory — solution of two problems of Bernoulli, iv. 129, Newton — on an analysis purely geometrical, iv. 442, D'Omerique — proportion of mathematical points, v. 678, . . Robartes — on the locus for three and four lines, xii. 6(), Pemberton — divis. of right lines, surfaces, and solids, xiii. 729, Glenie — porisms in the higher geometry, xviii. 345, . . Brougham — see Curves, Cycloid, Hyperbola, Parabola, &c. &c. George, II, observs. on dissect, the body of, xi. 574, Nicholls Georgium Sidus, see Herschel {Planet.) Gersten, Louis, of an arithmetical machine, viii. 25 — transit of Mercury over the sun, 1743, ix. 307 — new mural quadrant, ix. 347 Gestation, see Pregnancy. Geta, some account of the emperor, v. 203, .... Musgrave Ghisilieri, Marquis, lunar eclipse 171 8, vii. 33, ..Bologna 46 GLE INDEX. GRA Giants, extraord. size of Edra. Melloon, iv. 273, Musgrave — remarks in support of their existence, iv. 470, Molyneux . — existence of, before the Flood, vi. 85, Mather . — of a gigantic bregma, with rules for calculating the giant's size, viii. 388 Klein — gigantic people of Magellan Straits, xii. 391, . . . Clarke — see Bones. Giant's Causeway, in Ireland, descrip. of, iii. 529, Sir R. B. __— — ~ — — ■ iii. 656", , . . Foley ___ iii. 657, iv. 281, Molyneux ix. 457, x. 382, . . Pocoke — in Scotland, like that in Ireland, xi. 533, Bp. of Ossory, xi. 535,. . Da Costa — see Basaltes. Gibbes, Geo. Smith, on the conversion of animal muscle into fat, xvii. 389, 544 Gibraltar, of currents at the Straits, iii. 30, Smith Giffard, Mr., delivery of a foetus at the anus, vii. 433 Gilbert, Dr., biographical notice of, i. 187, Note Gilding, method of gilding silver, iv. 305, Southwell Giles, , a tumour in the lower part of the belly, iv. 132 — origin of a polypus in the nose discovered, iv. 152 Gilkes, Moreton, of petrifactions at Matlock ; cause of petrifactions in general, viii. 406 Gillaroo trout, account of the, xiii. 509, Barrington Gilpin, George, on the expansion of fluids, xvii. 272 — method of ascertaining the respective quantities of mixed spirits and water, xvii. 426 Ginseng, [panax quinquefolium] descrip. of, vi. 56, Jartoux .__ account of the genus araliastrum, vi. 314, . . . . Vaillant Gioeni, Count de, of a remarkable sort of rain which fell on Mount Etna, xv. 165 Gizzard, a pin in a fowl's gizzard, v. 240, Regnart Gizzard trout, see Gillaroo Trout. -Glands, of the glandulae renales in infants, ii. 450, . . Tyson — of the mucilaginous glands, iii. 464, Havers — discovery ©f two new glands, iv. 445, Cowper — figures of the glandulae renales, v. 323, Douglas — excretory duct from the renal gland, vii. 55, . . Valsalva — examination respecting the above discovery of Valsalva, vii. 84, 163, Ranby Glanvil, Joseph, on the Mendip lead mines, i. 186, 276 — nature and efficacy of the Bath waters, i. 36l Glaser, Christian, biographical notice of, ii. 395,. . . . Note Glass, method of making red glass, i. 270, .... Colepresse — to make the globe looking glass, iv. 317, • . . . Southwell — to paint glass in marble colours, iv. 317, Same — on the breaking of Bologna bottles, ix. 102, .... Bruni — experiments on unanneal'd glass, ix. l6l, .... Allamand — antiquity of in windows, xi. 232, 539i Nixon Glass (electricity) experiments on the attrition of, v. 307, 324, 344, 355, 41 1, Hauksbee — electricity of glass that has been exposed to fire, ix. 681, Bose — see Electricity. Glass, (optics) a glass to refract rays at a greater distance than usual, i. 6'8, Hook — to make convex glasses on a plane, i. 298,. . . . Mancini — see Object Glasses, Optic Glasses, Telescopes, Micro- scopes, &c. Glass (Nat. Philos.) rotation of tubes of, ix. 114, Wheler — phenomenon of the glass drop, ix. 675, Le Cat — of crystallizations observed in, xiv. 102, Keir Glass (Samuel) a dropsy from the want of a kidney, ix. 292 Glauber salt, how produced, viii. 11, Note Glenie, J., division of right lines, surfaces and solids, xiii. 729 — laws of universal proportion, xiv. 183 Glisson, Francis, m.d., biographical account of, i. 323, Note Globe, curious celestial globe, by l'Alleman, ii. 405 — account of Senex's globes, viii. 176 — asterisms of the ancient celestial, viii. 501, Latham — position of the colure in the ancient, viii. 607,. . . . Same — improvement of the celestial globe, ix. 351, . . Ferguson Glossopetrae, remarks on, i. 225, Steno ; Note, ibid. ii. 180, Lister Glover, Thomas, account of Virginia, ii. 301 Glow-worms, remarks on, i. 603, Templer — description of the cicindela volans, iii. 109, Waller Glue, a strong sort prepared from sturgeon, ii. 345 — difference of mucilage, size, and glue, xviii.725, Hatchett Gmelin, Phil. Fred., observations on ipecacuanha, ix. 126 Gnats, microscopical observations on, iv. 477, Leuwenhoek — uncommon swarms at Oxford, 1766, xii. 402, Swinton Gobien, Father, Le, account of the Philippine Isles, v. 442 Goddard, Jo. m. d., biograph. account of, ii. 426, . . Note — observations on a chamaelion, ii. 418 — on refining of gold with antimony, ii. 426 Godden, Mich., irregularity of the tide in the Thames, x. 6Q3 Gold, mines of in Hungary, and working, i. 437, . . Brown — modern method of amalgamation, i. 439* Note — incalescence of quicksilver with, ii. 267, B. R. — method of refining with antimony, ii. 426, . . Goddard — on the minute divisibility of, iii. 459, Halley — to gild silver, iv. 305, Southwell — experiments of mixing gold with tin, xv. 6'22, Alchorne — discovery of native gold in Ireland, xvii. 677, .... Lloyd xvii. 679, Milk — of the action of nitre on, xviii. 139, Tennant Goniometry, equations of goniometrical lines, ix. 357, Jones Gooch, Benjamin, morbid separation of the cuticle from the cutis, xii. 647 — on amputation above the knee, xiii. 666 — of aneurisms in the thigh, ibid. Goodricke, John, observ. of the star Algol, xv. 456, 545 — variation of light of /3 Lyrae, xv. 653 ^Cephei, xvi. 56 Goodyer, A. symptoms attending a serpent's bite, iv. 311 Goose, ten species of anas from Hudson's Bay, xiii 344, Forster Gooseberries, observ. on the seeds of, iii. 591, Leuwenhoek Gordius Medinensis, account of the, iv. 137, Lister Gordon, Rev. Pat., a cataract in Gottenburg river, iv. 525 — account of Tycho Brache's observatory, ibid. — of a water-spout in the Downs, iv. 564 Gordon, William, explosion of a fire-ball, viii. 559 Gotee, Father, of the island raised from the sea near San- torini, v. 647 Gorgonia, on the animal nature of, xiii. 720, Ellis — see Zoophyta. Gorsuck, Rev. Wm., bills of mortality of Holycross, 1/60, —1770, xii. 94; 1770,-1780, xv. 183 Gossamer, how produced, ix. 324, Arderon Gostling, Rev. Wm., explosion of a fire-ball, viii. 541, 560 Gottwald, J. C. m. d., of the plague at Dantzic, 1709, vi. 23 Gould, W., increase in weight of oil of vitrol, exposed to the air, iii. 11 — of a polypus in the heart, iii. 21 Gourdon, Sir Robt.,recipe for the bite of mad dogs, iii. 362 Gout, remarks on, i. 237, Behm — cure of the, ii. 300, BuschofF — remedies for, v. 362, Musgrave — enquiry into the causes of, vii. 254, Pinelli — nature of gouty concretions, xviii. 213, Wollaston Graaff, Regnerus de, biographical account of, i. 241, Note GR A INDEX. GRE GraafF, Regnerus de, on the parts of generation, i. 241, 271 — on the testicles, i. 392 Graft, a direction for engrafting apples, ii. 192 — see Trees. Graham, George, biographical account of, vi. 537, • • Note — extraordinary height of the barometer, ibid. — solar eclipse, London, vi. 604, vii 6l3, viii. 169, 306* — variation of the horizontal needle 1722, vii. 27 — observations with the dipping needle, vii. 94 — to avoid the irregularity of a clock arising from heat and cold, vii. 129 — lunar eclipse, London, vii. 6*09 ; viii. 11 6", 147, 714 — instrument for taking a latitude at any time of the day, vii. 673 — occultation of Mars by the moon, 1736*, viii. 148 — transit of Mercury over the sun, 714, ibid. — occult, of Aldebaran by the moon, 1738, viii. 470 — variations of the needle to the westward, ix. 499 Graham, Walter, m. d., watery cystises adhering to the peritonaeum, viii. 492 Grain, like wheat, falling from the sky, iii. 356, .... Cole Gramont, Father, description of the Chinese stove, xiii. 95 Granaries, description of several : — at London, i. l6'4 ; at Dantzic, ibid.; at Muscovy, ibid. Grand, Antonio Le, biographical notice of, i. 587, . . Note Grandi, Jacomo, anatom. observ., and strange births, i. 435 Grandi, Guido, biographical account of, v. 471, ... . Note — Nature and Properties of sound, v. 471 — collection of geometrical flowers, vi. 6*64 Granite, affinity between it andbasaltes, xvii. 8, ..Beddoes Grass in Norfolk destroyed by grubs, ix. 366, Baker Grasshoppers, see Cicada, Locusts. Graves, John, hatching of chickens at Cairo, ii. 4L3 Gravity (in general) remarks on, i. 6*11, Borelli — laws of, iii. 26l, Halley — law of decrease from the centre, iv. 142, Same — experiments on falling bodies, v. 6 12, Hauksbee — variation of, on the earth's surface, viii. 26, .... Stirling ■ xi. 604, Maskelyne — see Attraction, Motion (force of moving bodies.) Gravity (specific) weight of water in water, i. 374, Boyle — of various bodies, iii. 138, Oxford Society — of a variety of articles, iii. 523 — of several liquors in winter & summer, iv. 484, Homberg — of sev\ bodies, method of ascertaining, v. 481, Hauksbee — erroneous idea of Hauksbee respecting, v. 485, . . Note — of various oils and other fluids, v. 618, Hauksbee — of various metals, v. 6*98, Same — the strata of a coal-mine, v. 708, Same — of human blood, vi. 415, Jurin — of solids, caution in examining, vi. 538, Same — of various bodies, vii. 32, Fahrenheit • — of various metals, minerals, gems, stones, earths, sul- phurs, gums, woods, animal parts, salts, fluids, &c, tables of, ix. 536, Davies — of platinum, x. 98, Note — of living men, to ascertain, xi. 71, Robertson — of cork in different waters, xii. 204, Wilkinson — difference of fresh and sea- water, xii. 207, Same — of human bodies, xii. 207, Same — of inflammable air, xii. 303, Cavendish — various saline bodies, xv. 3, 236, 327, Kirwan — of metals, xv. 339, Same — on spec gravities at different temperatures, xv. 696, Same — of various fossil bodies, xvi. 6*44, ., Mills — of fluids, instruts. for ascertaining, xvii. 316, Schmeisser — of iron in its different states, xvii. 581, Pearson Gravity (specific) of corundum, sapphire, topaz, ruby, and diamond, tables of, xviii. 377 , Greville Grey, Sir James, discoveries at Herculaneum, x. 551 Gray, John, of the Peruvian bark tree, viii. 142 Gray, Stephen, microscope of a drop of water, iv. 97, 166 — to make concave parabolic specula, iv. 222 — on enlarging the divisions of the barometer, iv. 269 — parhelia seen at Canterbury, iv. 367 — unusual parhelion and halo, 1699, iv. 486 — of fossils found at Reculver Cliff", iv. 549 — to draw the meridian line by the pole star, ibid, and 56$ — observation of spots in the sun, v. 78 — electrical experts, vi. 490, vii. 449, 513, 539, 566, viii. 2, 51, 110 — instrument for taking levels, vii. 50 — catalogue of electrical bodies, vii. 539 — solar eclipse in Kent, 1733, vii. 6l4 — motion of pendulous bodies by electricity, viii. 65 Gray, Edw. W, m.d., biographical notice of, xvi. 407,Note — on increasing the electricity of glass, xvi. 407 — on Linnseus's class of amphibia; on the means of distin- guishing serpents that are venomous, xvi. 521 — an earthquake in various parts of England, 1795, xviii. 31 Greaves, John, biographical notice of, iii. 192, Note — experiments on the force of great guns, ibid — latitude of Constantinople and Rhodes, iii. 255 — object. toMr.Dee's plan of reforming the Calendar, iv.437 Greatrix, Mr., cures performed by stroking, iv.427, Thoresby Grebe (bird) account of the, xiii. 347, Forster Greece, observations on a journey through, ii. 284, Vernon Greek, see Money, Coins, Inscriptions. Green, Chas. astronom. observ. in the South Sea, xiii. 174 — transit of Venus, 1769, at Otaheite, xiii. 175, 177 Green, John, m.d. of a girl who was for a quarter of an hour under water without drowning, viii. 337 ■ — of Egede's Nat. Hist, of Greenland, viii. 722 Greene, Dr., death of, by a fracture of the os pubis, ix. 370, Cameron Greenhill, Thomas, four extraor. surgical cases, iv. 504 — of a scirrhous tumour, in the breast, v. 237 Greenland, on the natural history of, viii. 722, .... Egede Greenwich, latitude and longitude of, xvi. 218, Maskelyne — method of determining its relative position with Paris, xvi. 240, Roy Greenwood, Isaac, on meteorol. observ. at sea, vii. 225 — effects and properties of damps, vii. 365 — aurora borealis in New England, vii. 463 Gregory, David, biographical account of, iii. 79, . . ..Note — solution of the Florentine problem of Viviani, iii. 609 — defence of Mr. James Gregory as the inventor of the transformation of curves, iii. 673, v. 328 — properties of the catenarian curve, iv. 184, 456 — eclipse of the sun, Sept. 13, l6'99, iv- 426 — quadrature of the lunula of Hippocrates, iv. 453 — on Cassini's orbit of the planets, v. 152 Gregory, Rev. E., observ. of a comet, Jan. 1793, xvii. 294 Gregory, James, biographical account of, i. 232,. . . . Note — reply to the animadversions of Huygens on his book " De circuli quadratura," &c. i. 26*8, 319 — see Gregory, (David) Gregory, W , a pin taken from a child's bladder, viii. 239 — foetus resembling a hooded monkey, viii. 503 Grischow,AugustineNathaniel, lunar circle, and paraselenes, observed at Paris, ix. 567 — solar eclipse, 1748, ix. 56*8 ; 1750, x. 9 Greville, Hon. Charles, of the corundum stone from Asi% xviii. 356 4S GYM INDEX. HAL Grew, Nehemiah, biographical account of, i. 660, . . Note « — on the nature of snow, ii. 54 — on the pores in the skin of the hands and feet, iii. 35 — observations on a diseased spleen, iii. 460 — description of the American humming-bird, iii. 540 — on the food of the humming-bird, iii. 551 — of the number of acres in England, v. 620 Griffith, Mr., damage by lightning in Pemb. Col., xii. 254 Grimaldi, Father, biographical notice of, i. 675, .... Note Grindall, Richard, efficacy of bark in mortification, xi. 159 Grison's, brief view of the history of the, xiv. 7,. • Planta Groin, the fceces emitted from an ulcer in, iii. 230,Earnsha\v Gronovius, John F., m. d., biog. notice of, via. 559, Note — - method of preparing specimens of fish, ibid — of the fresh water polypus, viii. 607 — figure of the cobitis fossilis, ix. 335 Grosbeak, two species of, from Hudson's Bay, xiii- 339, Forster Grotta di Cani, some account of the, x. 137, Nollet Ground, see Sinking. Grouse, four species from Hndson's Bay, xiii. 334, Forster Grovestins, M-, earthquake at the Hague, 1756', x. 696 Guadaloupe, on the brimstone hill at, x. 701,. . Peyssonel Guattini, Ang. De, account of Congo and Brazil, ii. 434 Guericke, Otho, biographical account of, ii. 30,. . . . Note Guither, Dr., discourse on physiognomy, iii. 638 Gulielmini, Dominic, solar eclipse, 1684, iii. 569 Gull, the man of war-bird from Hudson's Bay, xiii. 348, Forster Gullet, case of a bullet lodged near, viii. 227, Ld. Carpenter Gullet, Christopher, usefulness of elder in preserving plants from flies, xiii. 319 Gulph-stream, heat of the water of the, xv. 115, Blagden Gulston, E., of an earthquake in the East Indies, xii. 12, 13 Gum lac, see Lac. Gunnery, exper. for improving the art of, i. 165, . . Moray — exper. to try the force of great guns, iii. 192, . . Greaves — a problem useful in, iii. 26'9, Halley — method of laying a mortar, iv. 27, Same — experiments in, by the committee of the it. s., viii. 598 — account of his new principles of, viii. 677, Robins — on the force of fired gunpowder, xiv. 282, .... Hutton Gunpowder, exper. of firing in vacuo, ii. 272, Huygens, &c. — experiments on, iii. 537* Leuwenhoek — of the quality of the air produced by gunpowder fired in vacuo, v. 1 83, Hauksbee — quantity of the air produced by fired gunp., v. 363, Same — experiments on the force of, xiv. 282, Hutton — expansive force of, compared with that of explosive air, xiv. 546, Ingenhousz — new experiments on, xv. 88, Count Rumford — exper. on the force of, xviii. 140, same; correction of an erroneous deduction of Co. Rumford' s, 156, Note Gun-shot wound, a boy shot through the lungs, ix. 67, Peters — peculiar case of a, xiii. 19, Woolcomb Gunter, Edm., biographical notice of, i. 189, Note Gunter's scale, of logarithmic lines on, x. 338, . . Robertson Gurnard (yellow) [callionymus lyra] desc. of, v. l6'2, Tyson Guthrie, Matthew, biographical notice of, xiv. 395, . . Note — on the antiseptic diet of the Russians, xiv. 395 — treatment, in Russia, of persons affected by the fumes of charcoal, xiv. 522 Guts, see Bowels, Viscera, Intestines. Guy, R., an extraord. substance in the body of a child, x. 565 Gwiniad[salmolavaretus]fromHudson'sBay, xiii. 412, Forster Gymnotus electricus, expts. and obs. on, xiii 597, Williamson — description of the, xiii. 600, Garden — anatomical description of, xiii, 666, Hunter H Haddocks, failure of, on the north coast, xvii. 243 Abbs Hadley, George, cause of the trade winds, viii. 19 — meteorological diaries, 1729-30, viii. 163 Hadley John, biographical notice of, vi. 646, Note — account of a catadioptric telescope, vi. 646 " — observations with his telescope, vi. 664, Pound — on the satellites of Jupiter and Saturn, vi.'665 — of an aurora borealis, October, 1726, vii. 159 — account of Bianchini's book respecting Venus, vii. 359 — instrument for taking angles, vii. 486 ; experiments made with it, 557 — method of using a spirit level at sea, vii. 620 — combination of lenses with reflecting planes, viii. 54 — meteorological observations, 1/31-35, viii. 617 — for Hadley's quadrant, see Quadrant. Hadley, John, m. d., description of a mummy examined in London, xii. 77 Haemoptysis, an uncommon case of, xi. 435, .... Darwin Haemorrhage, a strange bleeding in a child, ii. 169, Du Gard — periodical bleeding of the finger, iii. 156 — at the glandula lachrymalis, iii. 61 8, Havers — case of a periodical, iv. 547 Mano-inot — periodical bleeding of the thumb, iv. 586, Musgrave — from many parts of the body, v. 248, Mesaporiti — in the foot, viii. 727 Banyer — see Styptic. Haffenden, Richard, effects of lightning on a house, xiii. 659 Haighton, J., m. d., on the reproduction of nerves, xvii. 519 — on animal impregnation, xviii. 112 Hail, very large hail-stones, i. 168, Fairfax — unusual storm at Lisle, iii. 568 — an extraordinary storm at Chester, iv. 171, Halley — another account of the same storm, iv. 172 — storm in Hertfordshire, ibid, Taylor — Herefordshire, iv. 173 — — Monmouthshire, ibid, Lhwyd — on the generation of, iv. 197, Wall is — an extraordinary shower in Wales, v.678, Lhwyd — storm of in Yorkshire, v. 669, Thoresby — extraordinary storm in Virginia, xi. 273, .... Fauquier — see Storm. Hair, microscopical observations on, ii. 438, . . Leuwenhoek — a corpse long buried, converted into, ii. 490 — in several parts of the body, ibid, Tyson — another case of the same sort, ii. 50 1 , Sampson — a discharge of, from the body, iii. 157 — a hairy stone cut from the bladder, iv. 524, . . Wallace — balls of, extracted from the uterus, &c, v. 347, Yonge — bunch of, voided by urine, v. 518, Same — remarks on the above case, v. 518, Leuwenhoek — voided by a woman with the urine, viii. 489, Powell ; remarks on the same, 490, Sloane — voided by a man with the urine, viii. 491, .... Knight — in a tumour of the ovaruim, ix. 29, Haller Haines, Edwd., Saturn occulted by the Moon, l6*S7, iii. 350 Hale, Sir Matthew, biographical account of, ii. 411, Note Hale, Richd, m. d., discovery of the human allantois, iv. 577 — of the maxillary glands, &c, vi. 445 Hales, Rev. Stephen, biographical account of, vii. 1SS, Note — conveyance of liquors into the abdomen by tapping, ix. 8 — drawing of small stones from the bladder, ix. 159 — plan of a new thermometer ix. 406 — plan for checking the progress of fire, ix. 49S — electrical experiments, ix. 534 — strength of several purging waters; of Jessop's well, x.48 — remarks on the cause of earthquakes, x. 109 — antiseptic nature of lime-water, x, 551 HAL INDEX. HAM 49 Hales, Rev. Stephen, on blowing of fresh air through dis- tilling liquors, x. 635 — on ventilating of ships, x. 6*41 — to cure ill-tasted milk by ventilation, x. 642 Halesia [halesia tetraptei a] description of, xi. 508, . . . Ellis Halifax, Rev. W., journey from Aleppo to Palmyra, iv. 33 Hall, Captain, on the poison of the rattle-snake, vii. 196 Hall, in Saxony, rich salt springs at, i. 48 Haller, Albert, biographical account of, viii. 6*55, . . Note — account of his Enumeratio Stirp. Helvet., ibid, Watson — hair in a tumour of the ovarium, ix. 29 — of the centaurea orientalis, ix. 31 — case of scirrhosity of the cerebellum, ix. 49 — observations in morbid anatomy, ix. 349 — experiments on respiration, x. 5 — on the passages of the semen, x. 9 Hallerstein, account of the Jesuit missionaries, x. 220 — astronomical observations at Pekin, x. 238 Hallet, W., m. d., of an aurora borealis, Oct. 1725, vii. 158 Halley, E., ll.d., biographical memoir of, ii. 326,. . Note — on the aphelia, &c. of planets, ibid — astronom. observ. at Ballasore ; longitude of that place ; correction of some errors of eminent astromers, ii. 525 — motion of Saturn's 4th satellite, ii. 584 — theory of magnetic variation, ii. 624 — table of magnetic variations, ii. 625 — theory of the tides at Tonquin, iii. 67 — laws of gravity ; a problem in gunnery, iii. 26l — on the height of Mercury at different elevations above the earth ; on its changes with the weather, iii. 300 — on monsoons and trade-winds, iii. 320 — construct, of solid prob. by a parabola and circle, iii, 376 — quant, of vapour drawn by the sun from the sea, iii. 387 — roots of cubic and biquadratic equations, iii. 395 — circulation of vapour from the sea, iii. 427 — time and place of Caesar's descent in Britain, iii. 438 — conjunction of Venus and Mercury with the sun, iii. 448 — minute divisibility of gold, iii. 459 — the several species of infinite quantity, iii. 465 — cause of magnetical variation, iii. 470 — on the internal structure of the earth, iii. 472 — attempt to fix the value of annuities, iii. 483 — effect of heat and cold in expanding and condensing of fluids, iii. 505 — proportional heat of the sun in all latitudes, iii. 576 — examination of Albatenius's astronomical tables, iii. 586 — problem for finding the foci of optic glasses, iii. 593 — queries respecting the nature of light, iii. 600 — method of finding the roots of equations, iii. 640 — experiments and observations on evaporation, iii. 658 — moment of the sun's ingress into tropical signs, iv. 5 — construction of logarithms, iv. 18 — proposition in gunnery for laying a mortal1, iv. 27 — proposition for measuring cycloids and epicycloids, iv. 47 — account of the ancient Palmyra, iv. 60 — analogy of the logarithmic tangents to the meridian, iv. 68 — of a whelp voided per anum, iv. 110 — description of a Roman altar-piece, iv. Ill — true theory o\ tides, iv. 142 — of a hail storm at Chester, iv. 171 — the torricellian experiment on Snowden Hill, iv. 174 — lunar eclipse, Oct. l6"97, iv. 222 — of an extraordinary rainbow seen at Chester, iv. 277 — colours and diameter of the rainbow, iv. 527 -— remarks on Hook's marine barometer, iv. 56l — unusual parhelia, and circular arches, iv. 664 — - account of, and observations on, meteors, vi. 99 Halley, Edm. on the account of magnetical variations of the Royal Academy of Sciences, and on the longitude of Magellan Straits, vi. 112 — various observations of the solar eclipse, 1/15, vi. 155 — inquiry into the antiquity of the earth ; on the saltness of the ocean, &c, vi. 169 — account of new stars within 150 years, vi. 196 — account of newly discovered nebulae, vi 205 — meteoric lights March 17 16, accounted for, vi. 213 — to determine the sun's parallax, vi. 243 — of the unusual brightness of Venus, 1716, vi. 250 — on furnis-hing of air to divers in the sea, vi. 258, 522 — observ. of the moon's appulses to the Pleiades, vi. 308 — a small comet, London, 1717, vi. 322 — change of the latitudes of some fixed stars, vi. 329 — a meteor seen over England, March 1719, vi. 406* — longitude of the Cape of Good Hope, vi. 414 — an aurora borealis, Nov. 1719, vi. 441 — parallax of fixed stars, and magnitude of Sirius, vii. 443 — infinity of the sphere of the fixed stars, vi. 456* — number, order, and light of the fixed stars, vi. 457 — use of cross hairs in telescopes, vi. 494 — measuring of heights by the barometer, vi. 496 — effect of refraction of air in astronomical observ. vi. 517 — magnetic variation in the Pacific, vi. 519 — to find the planets' places by the stars, vi. 530 — observations of a parhelion, Oct. 1721, vi. 531 — longitude of Buenos Ayres, vi. 549 — solar eclipse, Greenwich, 1722, vi. 604 — longitude of Port Royal in Jamaica, vi. 619 Carthagena in America, vi. 620 — on the cause of the deluge, vii. 33, 35 — observ. of mercury determining its orbit, vii. 71 — defence of Newton's chronological index, vii. 172, 191 — proposal for finding the longitude at sea, vii. 501 — observations of latitude and variation from Java to St. Helena, vii. 552 — lunar eclipse, 1736, Greenwich, viii. 116 Halo, remark, halos about the moon, i. 146, Earl of Sandwich — seen at Paris, i. 457, Huygens — cause of halos, i. 458, Same — unusual halo and parhelion, iv. 487, Gray — large one about the moon, 1728, vii. 384, .... Weidler — seen at Rome round the sun, viii. 32, Revillac — observation of a remarkable halo, xi. 514, Barker — halos and parhelias seen in N. America, xvi. 181, Baxter Hamel, John Baptist du, biograp. account of, i. 536, Note Hamel, Henry Louis du, biograp. account of, viii. 420, Note — exper. on madder-root in tinging the bones, viii. 420 Hamilton, Hon. Charles, descrip. of a water clock, ix. 236 Hamilton, Rev. Hugh, d. t>., biog. notice of, xi. 706, Note — properties of mechanic powers, ibid. — on the nature of evaporation, xii. 223 Hamilton, Rev. J. Aug., transit of Mercury, 1782, xv. 456 Hamilton, Rob., m. d., suppression of urine cured by a punc- ture of the bladder through the anus, xiv. 113 Hamilton, Hon. Sir Wm , biog. account of, xii. 417, Note — eruption of Vesuvius, 1765, ibid Etna, 1766, xii. 419 Vesuvius, 176*7, xii. 494 — remarks on Vesuvius and other volcanoes in the neigh- bourhood, xii. 592 — journey to mount Etna, and examination, x'ni. 1 — nature of the soil of Naples, xiii. 92 — effect of lightning at Naples, xiii. 455 — traces of volcanoes on the banks of the Rhine, xiv. 276 — eruption of Vesuvius, 1779, xiv. 6l3 G 50 HAT INDEX. HEA Hamilton, Hon. Sir Wm,, earthquakes in Italy, 1783, xv. 373 — state of Vesuvius after the eruption, 1784, xvi. 181 — journey to Abruzzo, and to Ponza, ibid — eruption of Vesuvius, 1794, xvi i. 492 Hamniam Pharoan water, analysis of, viii. 556, .... Perry Hampe, J. Henry, m. p., descrip. of the narhwal, viii. l6l — description of the manis pentadactyla, xiii. 8 Hanbury, W., meth. of making coal-balls at Liege, viii. 4S3 Hanckewitz, Amb. Godf., biograp. notice of, vii. 596, Note — experiments on the phosphorus of urine, ibid — analysis of the Westashton waters, viii. 522 Handel, instance of the early genius of, xiii. 13, Barrington Hanley, P., m. d., of a steatomatous tumour in the abdomen, xiii. 108 Hardisway, P., m. d., dissec. of a man dead of stone, vi. 657 — caries and separation of the cheek-bone, vii. 2l6 Hare, observations on the dissection of, v. 314, . . Marchetti — specific characters distinguishing it from the rabbit, xiii. 267, Barrington — two species of, from Hudson's Bay, xiii. 328, . . . Forster Harmattan, an African wind, account of, xv. 23, Dobson Harmer, Thomas, on the fecundity of fishes, xii. 441 Harris, Daniel, transit of Venus, 1769, Windsor, xii. 676 Harris, John, d. d., biographical notice of, v. 149, • . Note — observations of animalcula in water, iv. 89 — Roman inscription at Caerleon, vi. 394 — efficacy of Villette's burning-glass, vi. 405 Harris, Joseph, astronomical observ. at Vera Cruz, vii. 224 — magnetical variations in the Atlantic, vii. 604 — description of a water- spout, vii. 606 Harrison, John, biographical account of, x. 284, .... Note — small wasps in New England, x. 1 82 — to remedy the expansion of pendulums, x. 284 Hart, Cheney, m. d., exper. in medical electricity, x. 534 — cure of a paralytic arm by electricity, x. 700 Hartley, David, biographical account of, viii. 205, . . . Note — case of hydrophobia, ibid. — of a calculus which worked thro' the perinaeum, viii. 405 — account of Trew's dissertatio de difFerentiis, &c. viii. 425 Hartmann, P. J., shape of an embryo of 4 months, . . iv. 236 — account of amber, iv. 347 Hartop, Martin, on the cause of earthquakes, iii. 555 Hartsell Spa Water, discov. and nature of, xi. 87, Walker — chemical analysis of, xi. 88, Note — observations on, xi. 430, Rutty Hartz Mines, barometrical measurement of their depth, xiv. 180, 574, De Luc Harvey, Wm., m. d., account of his discovery of the circu- lation of the blood, i. 319, Note — dissection of the body of Thomas Parr, i. 3 1 9 Harwich ClifF, ace. of, & fossil shells found there, v. 124, Dale Harwood, (Prof.) exper. of transfusion of blood, i. 185, Note Harwood, John, d. d., of a Roman hypocaust, v. 291 Haskins, Joshua, improvement of his water engine, vi. 55, Desaguliers Hassel, R., the eye cured of a wound from a piece of wood, ix. 566 Hasselquist, Dr., method of making sal ammoniac in Egypt, xi. 433 Hassenfratz, M., experiments on hepatic airs, xvi. 286 Hasted, Edward, on chesnut trees in England, xiii. 1 J 6 Hatchet, see Antiquities. Hatchett, Charles, analysis of the Carynthian molybdate of lead, xviii. 4 — experiments on molybdic acid, xviii. 21 — analysis of terra australis, xviii. 290 — analysis of the water of the Mere Diss, xviii. 428 — analytical experiments on shells and bone, xviii. 554 Hatchett, Chas., chemical experiments on zoophyta,xviii.706 — on the component parts of membrane, xviii. 725 Hatley, Griffin, u. d., description of shell-like fossils, iii. 4 Hauksbee, Francis, account of, v. 147, Note — cause of the mercurial descent in a storm, ibid. — gun-powder fired on red hot iron in vacuo, v. 182 — on the quality of the air produced as above, ibid. — production of light from phosphorus in vacuo, v. 196 — experts, on the sound of a bell in vacuo, &c. v. 202, 203 — resilition of bodies in air and in vacuo, v. 208 — descent of bodies in the exhausted receiver, ibid. — experiments on the mercurial phosphorus, v. 254 the attrition of bodies in vacuo, v. 270 — comparative weight of water and air, v. 288 — ascent of water in small tubes, in vacuo and in air, v. 289 — electric, of glass by attrition, v. 307, 324, 344, 355, 411 — experiment of compressed air on hemispheres, v. 356 — quantity of air from fired gunpowder, v. 363 — effect of a violent impulse on the spring of air, v. 364 — electricity from attrition, v. 413 — densities of the air at different temperatures, v. 41 6 — condensing of several atmospheres of air, v. 451 — electricity of sealing-wax, v. 452 — weight of water under differ, circumstances, v. 453, 470 — exper. on the seeming spontan. ascent of water, v. 464 — densities of water at different temperatures, v. 469 — experiments of freezing common W3ter, and water freed from air, v. 482 tinctured waters, v. 483 to try the specific gravity of bodies, v. 484 — sound not transmissible through a vacuum, v. 499 — propagation of sound through air, v. 500 water, ibid. — phosphoric nature of pitch, v. 509 — sulphur not productive of light, v. 528 — experiments on the fall of bodies, v. 6l2 — effects of air vitiated by heat, v. 6l4 — refractions and specific gravity of fluids, v. 616 — of liquors occupying less space when mixed, v. 644 — light through a metallic body by attrition, v. 645 — ascent of oil between planes, v. 659 — necessity of air to fishes, v. 669 — suspension of oil between planes, v. 6"79 — power of the loadstone at different distances, v. 696 — specific gravities of several metals, v. 698 — ascent of water between planes, v. 707 ; vi. 40 — specific gravity of the strata of a coal mine, v. 708 — ascent of spirit of wine between planes, vi. 40, 41 Haughton, M., method of making salt water sweet, i. 549 — on another passage for the urine, i. 550 Havers, Clopton, m. d., some account of, iii. 46l, . . . Note — haemorrhage from the glandula lachrymalis, iii. 6l8 — hypothesis of the concoction of food, iv. 400 Hawk, several species from Hudson's Bay, xiii. 331 Hawkins, — , solar eclipse Nov., 1722, at Wakefield, vi. 604 Hay, several sorts of plants fit for, iv. 136, Lister Haydon, Richard, transit of Venus, June, 1761, xi. 559 Haygarth, H , m. »., bills of mortality of Chester, 1772, xiii. 496; 1793, 595 — mortality of Chester compared with that of Northampton, London, and Norwich, xiii. 498 — population and diseases of Chester, 1774, xiv. 311 Hazen, Willem Van, fall of rain at Leyden, 1751, x. 233 Head, a monstrous, with eyes united, i. 29, Boyle — cure of a fractured head, viii. 439, Cagua — instance of an extraord. large head, xii. 551, Benvenuti Hearing, on the organ of, iv. 448, Vieussens — see Ear, Deafness. HEB INDEX. HEP 51 Hearing, for hearing of fishes, see Fishes. Hearne, Thomas, biographical notice of, v. 50, Note — remarks on some ancient brass weapons, v. 511 — aurora borealis, at Streatham, vi. 442 Hearne, U., m. d., of the lake Wetten, in Sweden, v. 207 Heart, remarkable appearance in, i. 30 — Treatise on the heart, i. 330, 6 12, Lower — motion of the urchin's heart cut out, ii. 6l, . .Templer — influence of respiration on the motion of, iv. 698, Drake — enlargement of the left ventricle, vi. 181, ... . Douglass — muscular motion of, vi. 375, Jurin — foramen ovale, found open in an adult, viii. 54, Amyand — Dr. Stuart on the structure of, viii. 483, Mortimer — turned upside down, case of, viii. 508, Torres — much enlarged, case of, with observ., xi. 585, Pulteney — effects of a blow on the heart, xii. 39 — case of a transpos. of the heart, &c, xvii. 295, Abernethy — observations on the foramina thebesii, xviii. 286, . . Same — an unusual formation of the, xviii. 332,. Wilson — see Blood, Polypus. Hearths, see Population. Heat, (nat. phil.) degrees of boiling liquors, vii. 1, Fahrenheit — power of the body to resist, xiii. 604, 695, .... Blagden — diminution of weight in bodies by heat, xvi. 13, Fordyce — on the conducting powers of air, &c, xvi. 108, Rumford — experiments on the nature of, xvi. 288, Fordyce — observations on subterranean heat, xvi. 377». • • . Hunter xvi. 406, Six — on producing light by heat, xvii. 128,215, Wedgwood — on conducting powers of various subst., xvii. 135, Rumford — source of the heat excited by friction, xviii. 278, . . Same — on the weight ascribed to heat, xviii. 496, Same — similarity of light and heat, xviii. 692, 748, . . Herschel — see Thermometer, Fire. Heat (meteor.) warmth of the air, Jan., 1742, viii. 548, Miles — thermometrical observations, x. 126, Stedman — of the air, July, 1757, at Plymouth and London, xi. 176, 204, Huxham — dif. of heat at Edystone and Plymouth, xi. 191, Smeaton — of July, 1757, effects of on the health, xi. 204, . . Huxham — at Georgia, xi. 277, Ellis — of the climate at Bengal, xii. 423, Martin — of London and Edinburgh compared, xiii. 685, Roebuck — of the variation of local heat, xv. 609 ; xvi. 404, .... Six — see Meteorological observations, Weather. Heated room, experiments in, xiii. 604, 695, .... Blagden xiii. 687, Dobson Heathcot, Thom., observ. of the lunar eclipse, 1681, ii. 557 — tide, and magnetic variation at Cape Corso, iii. 32- Heavens, construction of, xv. 6ll, 680, xvi. 586, Herschel Heberden, Thomas, m. d., observations in ascending the peak of Teneriffe, x. 230 — the weather and fall of rain at Madeira, x. 232, 488 — earthquake of 1751 at Madeira, x. 66'4 176l at Madeira, xi. 543 — proportion of the decrease of heat from elevation, xii. 218 — increased mortality at Madeira, xii. 475 — quantity of rain different at different heights, xii. 659 — eclipses of Jupiter's first satellite, at Madeira, xiii. 82, Heberden, Wm., m. d., biograph. account of, x. 103, Note — of a very large human calculus, ibid — effects of lightning on a church, xii. 126 — of a salt on the peak of Teneriffe, xii. 195 — a stone spontaneously voided from the bladder, xii. 219 — mean heat of every month for 10 years in London, xvi, 384 Heberden, William, Jun., M. d. influence of cold on the health of die inhabitants of London, xviii.- 1 Hedgehog, its anatomy compared widi a porcupine, iii. 391 Hce, Christ., press, of weights on moving machines, x. 558 Heel, see Tendon of Achilles. Heights, baro. measure, of, in Savoy, xiv. 203, Shuckburgh — in Britain, xiv. 237* Roy — comparison of Col. Roy's rules for measuring them with his own, xiv. 405, Shuckburgh I — see Barometer. Heinsius, G. gold-coloured glazing for earthen- ware, viii, 606 — disappearance of Saturn's ring, 1743-4, viii. 722 Heister, Laurence, ai. d., biog. account of, vii. 447, Note — of a stone voided by the urethra, ibid Hejera, acountof this Mahometan era, xvi. 509, . . Marsden — table of the years of the Hejera corresponding with the Christian era, 5 14> Same Helena, (St.) recommended for making observations of the lunar parallax, xi. 519, De La Caille Hellins, Rev. J., theor. for computing logarithms, xiv. 682 — on the equal roots of equations, xv. 317 — improvem. of Halley's quadrature of the circle, xvii. 414 — improvem. of Jones' computation of the log. 10, xvii. 699 Emerson's xvii. 702 — value of slowly converging series, xviii. 312 — to obtain swiftly converging series, xviii. 408 — summation of slowly converging series, xviii, 415, 599 Helmont, LB. Van., biographical account, ii. 155, ..Note — preparation of laudanum, ii. 155 Helvetia, — see Switzerland. Helvetius, Adrian, m. d„ biograp. account of, vi. 198, Note — medicinal virtues of the pareira brava, ibid. Hemlock, medicinal virtues of its leaves, iv. 1 83, .... Ray — persons poisoned by, ix. 38, Watson — description of the cicuta aquatica [virosa] ix. 26 1, Same — of the proper sort for medicinal uses, xi. 530, .... Same — in its green state, successfully taken for cancer, xii? 37, 254, Colebrook — experiments on different extracts of, xii. ] 20, . . Morris Hempseed, an indissoluble salt from, xii. 616, Ellis — cultivation of the Chinese, xv. 180, Fitzgerald Henbane, the smell pleasant, in insects feeding on it, i. 602 « Lister — medicinal quality of, vii. 6 10, Sloane — effects of the poison of, viii. 267, Patouillat — effects of, x. 185, Stedman; remarks, 1 86, .... Watson Hemorrhage, see Hemorrhage. Henchman, Rev. Mr., effect of the mixture of the farina of blossoms, ix. 169 Henley, Wm., effects of lightning at Tottenham Court- road chapel, 1772, xiii. 307 — electricity of fogs, xiii. 313 — different efficacy of pointed and blunt lightning con- ductors, xiii. 512 — various experiments in electricity, xiii. 551, xiv. 130 — effects of lightning on a house with conductors, xiii. 659 bullocks, xiv. 90 — machine for perpetual electricity, xiv. 97 — impermeability of glass to electric fluid, xiv. 473 Henry, IV. of France, encouragement of silk-worms, i. 30 Henry, Tho., earthquake at Manchester, 1777, xiv. 334 Henry, W., d. o., the Wicklow copper mines, x. 280, 338 — an extraordinary stream of wind, x. 303 — ossification of the tendons and muscles, xi. 335, 336, 542 Henry, Wm., experts, on carbo. hydrogenous gas, xviii. 221 — experts, for decomposing muriatic acid, xviii. 641 Henshaw, Thos., observa. and experts, on May-dew, i. 13. Hepatic air. — see Airs, Gas. 52 HER INDEX. HI G Hepatitis, successful treatment of, xii. 289, Smith Herb, discovery of a new medicinal herb, iv. 654, Marchand Herculaneum, discovery of the remains of, viii. 403, Sloane — of the statues and other antiquities found at, viii. 435, x. 328, 493, 549, 585, 689, xi. 79* 237, Paderni — particulars of things found at, viii. 437, Knapton ■i viii. 438, Crispe — of some antique pictures found at, ix. 663, .... Hoare — principal pictures found at, ix. 620, Blondeau — description of the pictures, &c, x. l66, Freeman — description of, and what was found, x. 1 72 — discoveries at, x. 447, Spence • x. 551, Gray x. 584, Anonymous — ancient books and mss. at, x. 586, Locke — remarks on a piece of music of Philodemus, found at, x. 685, J Watson — progress in unrolling the mss., and formation of an aca- demy for explaining the antiquities found at, x. 709, Condamine — some antiquities found at, xi. 85, Nixon Herissant, M., m. d., experts, on the Indian poison, x. 144 Hermaphrodite, history and description of, i. 223 ... Allen ■ account of an extraordinary, iii. 356,. . Veay ■ another, x. 170, .... Parsons — dissection of an hermaphrodite dog, xviii. 485, . . Home — observations on hermaphrodites, ibid Same Hernia, see Rupture. Herrn Groundt, see Copper. Herschel, Wm., lld., a periodical star in collo ceti, xiv. 689 — observations of the mountains of the moon, xiv. 717 — observations of the rotation of the planets, xv. 50 — account of a comet [planet] 1781, xv. 154 — a micrometer for the angles of position, xv. 155 — on the parallax of the fixed stars, xv. 196 — a catalogue of double stars, xv. 213 — description and use of a lamp micrometer, xv. 229 — on the magnifying powers of his great telescope, xv. 234 — on the name of his new planet, xv. 324 — diameter and magnitude of the new planet, xv. 325 — motion of the solar system, and changes in the fixed stars, xv. 397 — figure, appearance, &c. of Mars, xv. 531 — of the construction of the heavens, xv. 6ll, 680, xvi. 586 — a catalogue of double stars, xv. 642 — observations of 1000 new nebulae, xvi. 158, 586 — vision as affecting by the size of the optic pencil, xvi. 165 — remarks on the comet of 1786, xvi. 170 — discovery of three volcanos in the moon, xvi. 255 — description of his planet and its satellites, xvi. 489 — observations of the comet of 1788, xvi. 56*0 — two new satellites of Saturn, with remarks on its ring, figure, &c. xvi. 6l3 — rotation of Saturn, and tables of the satellites, xvi. 730 — on the nature of nebulous stars, xvii. 18 — on Saturn's ring, and 5th satellite, xvii. 117 — account of a comet, Dec. 15, 1791, xvii. 126 — periodical appearance of 0 Ceti, ibid — disappearance of 55 Herculis, xvii. 127 — rotation, atmosphere, &c. of Venus, xvii. 330 — observation of a quintuple belt on Saturn, xvii. 346 — appearances of the sun during an eclipse, 1793, xvii. 351 — rotation of Saturn on its axis, xvii. 356 — nature and construe, of the sun and fixed stars, xvii. 478 — description of his 40-feet reflecting telescope, xvii. 593 — observations of the comet of 1795, xvii. 698 — method of observing the changes in fixed stars, xvii. 712 — en the stability of the solar light, xvii. 723 Herschel, Wm , ll.t>., of the period, star « Herculis,xviii.6l — rotatory motion of the fixed stars, xviii. 62 — completion of Flamsteed's cat. of fixed stars, xviii. 177 — notes to his catalogues of fixed stars, xviii. 1 7g, 475 — changeable brightness, rotation, and diameters of Jupiter's satellites, xviii. 187 — discovery of 4 new satellites to the Herschel planet, and of a retrograde motion of the old ones, xviii. 270 ' — on the power of penetrating into space by teles, xviii. 580 — powers of the prism, colours to heat, and ilium, xviii. 675 — method of viewing the sun advantageously with powerful telescopes, xviii. 683 — refrangibility of the invisible solar rays, xviii. 688 — on the similarity of the nature of light and heat xviii 692, 748 Herschel, Caroline, discovery of a comet, 1786, xvi. 170 1794, xvii. 335 1795, xvii. 698 Herschel (planet) account of the, xv. 324, Note — of its diameter and magnitude, xv. 325, Herschel — discovery of two of its satellites, xvi. 214, Same — descrip. of the planet and its satellites, xvi. 489,. . Same — retrograde motion of the satellites, and discovery of 4 new ones, xviii. 270, Same Hesiod, and Homer, on the ages of, x. 441, ...... Costard Hessia, see Basaltes. Hessian Bellows, see Bellows. Hevelius, John, biographical notice of, i. 36, Note — improvement of optic glasses, ibid — prodromus cometicus, account of, i. 39 — answer to queries: on amber, i. 126 j swallows, ibid — ona new star in the Swan's breast, i. 127 — calculation of a solar eclipse, i. 137 — figure of the Swan, and a new star in it, i. 137 — magnetical variations at Dantzic, i. 514 — a new star in the Swan, i. 528,607; observation of Saturn,529 — eclipse of the moon, Sept. 1 670, i. 542 — conjunc. of Venus with the moon, Oct. 1670, i. 543 — some celestial phenomena, i. 658 — observation at Dantzic of a comet, 1672, i. 696 ; 1677, ii. 39*, 1682, ii. 557 — parhelia seen at Marienburg, ii. 130 — on the use of telescopic sights, ii. 130 — on Kepler's manuscripts, ii- 131 — account of a new chronological work, ii. 134 — new stars in the Whale and Swan, ii. 384 — Jupiter occulted by the moon, 1679, ii. 481, iii. 331 — 3 conjunc. of Saturn and Jupiter, 1682-3, ii. 662 — ■ occupations of fixed stars by the moon, ii. 663 - observations of a comet, 1684, ii. 6S3 — of his loss by fire, and Dr. Halley's visit, &c. iii. 2l6 — on diagonal divisions, iii. 220 — eclipse of the moon, 1685, iii- 245 Hey, Wm., observ. of some luminous arches, xvi. 637 Hewson, Wm., biographical account of, xii. 556, .... Note — of the lymphatic system in birds, ibid ■ in amphibia and fishes, xii. 633 — experiments on the blood, xiii. 64 — figure of the particles of blood, xiii. 455 Hickes, George, d. n., biographical notice of, v. 243, Note — explanation of a Saxon antiquity, iv. 469 — inscription on the statue of Tages, v. 243 Hiero-fountain in Hungary which generates ice and snow, description of, xi. 6*33, Wolfe Hieroglyphics, connection between the Egyptian and Chi- nese character, xiii. 685 Higgins, Bryan, m. d., detonation and fire by the contact of tin-foil, with salt of copper and nitrous acid, xiii. 404 HOL INDEX. HOO 53 Higgins, Bryan, m. d., use of an amalgam of zinc for elect. excitation, xiv. 446 Higbmore, — , m. d., on the Scarborough spa ; a salt spring in Somersetshire ; a medical spring in Dorset, i. 419 Hill, the subsiding of part of a, vi. 69, Bishop of Clogher — see Attraction, Volcanoes. Hill, Mr., on the great age of Henry Jenkins, iv. 167 Hill, Sir John, biographical notice of, ix. 200, Note — on the seeding of mosses, ibid — on Windsor loam, ix. 337 Hillier, J., observations at Cape Corse, iv. 201 Himsel, Nic.de, m.d., a rare species oforthoceratites, xi.26l — case of palsy cured by electricity, xi. 372 — production of extreme cold, xi. 480 Hind, anatomy of the Sardinian, iii. 392 Hindoos, table of their eras compared with the Christian, xvi. 74fj, Marsden — on their civil year, and account of 3 Hindoo almanacks, xvii. 250, Cavendish Hippocrates, on squaring the lunula of, iv. 452, Perks, Gregory, Caswell, Wallis — description of his ambe, viii. 659> Le Cat Hire, Philip de la, biograph. notice of, ii. 353 — new magnetical compass, iii. 381 Hirst, Wm., a fire ball seen at Hornsey, 1754, x. 530 Hirst, Rev. Wm., transit of Venus, 1761, xi. 596 — an earthquake in the East Indies 1762, xii. 12 — solar eclipse observed at Ghyrotty, ibid — lunar eclipse observed at Calcutta, xii. 13 — phenomena of the transit of Venus, 1769> xii. 639 Hirta, description of the island, and manner of climbing the rocks for eggs and sea-fowl, ii. 4l6, Moray Hirudinella marina, account of, vii. 424, Garcin Hoare, Mr., antique pictures at Herculaneum, ix. 363 Hobbes, Thomas, biographical account of, i. 107, .... Note Hobbes's book De principiis geometrarum, animadversions on by Dr. Wallis, i. 107 Hoboken, Nicholas, biographical notice of, i. 442, . . Note Hobson, Joseph, increase of the seeds of mallow, viii. 63 1 Hodgson, James, biographical notice of, v. 134, 481, Notes — observation of a lunar eclipse, Dec. 1703. ibid — eclipses of Jupiter's satellites, 1732, vii. 481 j 1733, vii. 550 ; 1734, vii. 588 ; 1735, vii. 642 ; 1736, viii. 1 ; 1737, viii. 55 ; 1738, viii. 84 ; 1739, viii. 141 ; 1740, viii. 235 ; 1750, ix. 527 ; 1751, ix. 699 — on the accuracy of Flamsteed's tables, viii. 1 — Chinese astronomical observations, viii. 628 — observations at Pekin of the comet of 1 742, ix. 267 Hodgson, John, agitation of the waters at Medhurst, x. 649 Hodgson, Lucas, m. d , of a fire in a coal mine, ii. 359 Hody, Edw., m. n., a bony substance in the womb, viii. 56 Hog, see Musk-Hog. Holbroke, William, m. d., disorder from swallowing plum- stones, v. 552 Holder, Wm., d. d., biographical account of, i. 242, Note — remarks on deafness, ibid Holdsworth, Rev. F., agitation of the waters at Dartmouth, 1755, xi. 1 Holland, curiosities seen in, v. 45, Oliver Holland, Samuel, latitude of the islands of St. John and Cape Breton, xii. 507 — astronomical observations in North America, xii. 642 — eclipses of Jupiter's satellites, N. America, xiii. 527, 528 Hollandia Nova, see New Holland. Hollings, , m. d., dissection of a woman supposed pregnant, vi. 242 Holloway, Rev. B., fuller's earth pits in Bedfords., vi. 674 Holly, on the sex of, x. 486, Martyn Holly, on Mr. Martyn's opinion of the sex of, x.487, Watson Hollman, Sam. Christ., on vegetable physiology, viii. 513 — differences of heights of barometers, viii. 578 — on freezing, ix. 93 — experiments on electric fire, ix 9* — new micrometer, ibid — agreement of barometers with the weather, ix. 65 1 — of fossils in mountains of Germany, xi. 435 Holmes, Major, success of pendulum watches for the longi- tude, i. 7 Holt Waters, nature and properties of, vii. 253, 338, Lewis Holt, Sir C, disorder from swallowing stones, iv. 381, 630 — ' a child with the intestines, kc. in the thorax, iv. 630 Hoi well, John Zeph., a new specimen of oak, xiii. 306 Hollyhock, on the farina fgecundans of, ix. 230, . . Badcock Homberg, M. biographical notice of, iv. 483, Note — quantity of acid salts from acid spirits, ibid Home, Robert, first joint of the thumb torn away with all the flexor tendon, xi. 235 Home, Everard, account of a new marine animal, xvi. 1 — account of a double headed child, xvi. 663, xviii. 443 — cases of horny excres. from the human body, xvii. 28 — account of some observations by Mr. J. Hunter on the crystalline humour, xvii. 343 — nature and use of the muscles of the eye, xvii, 453, 660 — on the principle of muscular motion, xvii. 525 — organs and mode of generat. of the Kanguroo, xvii. 535 — anatomy of the sea otter, xviii. 34 — of the changes which blood undergoes whenextravasated into the bladder, xviii. 64 — on the morbid action of the straight muscles and cornea of the eye, xviii. 74 — on the orifice in the retina of the eye, xviii. 326 — structure of nerves, particularly the optic, xviii. 430 — dissection of an hermaphrodite dog, xviii. 485 — observations on hermaphrodites, ibid — on the teeth of graminivorous animals, xviii. 519 — structure and use of the membrana tympani, xviii. 566 — mode of hearing after destruction of the membrana tympani, xviii. 630 — on the head of the ornithorhyncus paradoxus, xviii. 746 Hommel, account of the jaculator fish, xii. 321 Homer, and Hesiod, on the ages of, x. 440, Costard Hondt, , m. d., agitation of the waters at the Hague, 1755, x. 655 Honey, method of seeking in the woods of New England, vi. 509, Dudley Honey-combs, form of the cells of, viii. 709, . . Maclaurin Honey-bird, see Cuculus indicator. Hook, Robert, biographical account of, i. 3, 437, . . . Note — observation of a spot in one of Jupiter's belts, i. 3 — some account of his micrograph ia, i. 13 — inquiries for seamen on long voyages, i. 53, 153 — rotation of Jupiter on its axis, i. 60 — observations on the planet Mars, i. 65 — a glass with a small plano-convex sphere, to refract rays to a focus at a greater distance than usual, i. 66 — a newly contrived wheel-barometer, i. 72 — phases of Mars and rotation round its axis, i. — observation of the planet Jupiter, i. 83 — Saturn, i. 80 — exper. of blowing into the lungs with bellows, i. 194 — description of Gascoigne's micrometer, i. 195 — contrivance to make the image of a thing appear on a wall, i. 269 — appearance of Saturn's ring, i. 530 — observation of spots in the sun, i. 648 — observ. of an eclipse of the moon, 1 671,1. 648; 1 675, ii.l 87 54 HOS INDEX. HUN Hook, Robt., account of his philos. collections, ii. 473, Note — a help for short sightedness, ii. 508 — best form of sails for mills and ships, ii. 509 — essay on the Chinese characters, iii. 285 — eclipses of Jupiter by the moon, iii. 294 — to increase the divisions of a barometer, iii. 343 Hope, John, M. n., biographical account of, xv. fJ40,Note — medicinal quality of the rheum palmatum, xii. 26l — of a rare plant of the Isle of Skye, xii. 642 — description of the asafeetida plant, xv. 640 Hope, T., m. d., remarkable operation on die eye, ix. 83 — M. Daviel's method of couching, x. 287 Hopkins, J., large stag's horn found in the sea, vii. 528 Hopton, Richard, eruption of a boiling spring, v. 6S0 Horace, remark on a passage in, iv. 712, Molyneux Horizon, see Sun, Moon, Quadrant, &c. Home, H., of the^iron made from magnetic sand, xi. 689 Home, J. Van, biographical account of, i. 241, .... Note — on the parts of generation, i. 241, 271 Horns, on the formation and origin of, iii. 49,. . Malpighi — growing on a girl's body, iii. 229, Ash — of an immense size found in Ireland, iv. 156, Molyneux — horny excrescences on the fingers, &c. iv. i76> • • Locke — another similar instance, v. 201 , Wroe — found underground in Ireland, vii. 154, Kelly — very large found at Wapping, vii. 180, Sloane — large stag's horn found in the sea, vii. 528,. . . . Hopkins — a deer's horn in the heart of an oak, viii. 360,. . . . Clark — horn of a fish in a ship's side, viii. 536, Mortimer — uncommon deer's horns in Yorkshire, ix. 225, Knowlton — and head of a stag in Derbyshire, xvi. 9, Barker — observations on horny excrescences from the human body, xvii. 28, Home — see Rhinoceros, Monsters, &c. Hornsby, Rev. T., on the sun's parallax, xii. 44 — solar eclipse, 1764, at Oxford, xii. 115 — proposal for observing the transit of Venus, xii. 265 — transit of Venus, 17§9> Sherburn and Oxford, xii. 625 — solar eclipse, 1 7^9 > xii. 626 — sun's parallax from the transit of Venus, 1769, xiii. 220 — on the proper motion of Arcturus ; and decreased ob- liquity of the ecliptic, xiii. 386, Note Horrox, Jeremiah, biographical account of, ii. 12, .. Note — remarks on his lunar system, ii. 220, Flamsteed Horse, an undescribed blemish in the eye, i. 2l6,. . Lower — extraordinary cases of calculus in, ii. 544, 545,. . . . Note — staked in the stomach, cure of, iv. 65, Wallis — of a horse bitten by a mad dog, x. 54, Starr Horsefall, James, on questions in chronology, xii. 519 . — transit of Venus, 1769, London, xii. 625 Horsley, Rev. Mr., fall of rain in Northumb., 1722-3, vi.658 Horsley, J., on the lunar method for the longitude, xii. l6l Horsley, Rev. Sam., d. d., biog. account of, xii. 411, Note — on the sun's distance from the earth, ibid — on the height of the sun's atmosphere, xii. 456 — sun's distance computed by gravity, xii. 619 — transit of Venus and solar eclipse, 1769, xii. 629 — difficulties in the Newtonian theory of light, removed, xiii. 65, 210 — on the sieve of Eratosthenes, xiii. 315 — notes on Bailly's theory of Jupiter's satellites, xiii. 430 — on De Luc's rule for the measurement of heights by the barometer, xiii. 531 — state of the weather from the journals of the r. s., xii' 6l6; xiv. 44 — of polygons in and about circles, xiii. 653 Horticulture, see Gardening. Hosack, David, m. d., observations on vision, xvii. 403 Hosty, Ambrose, m. d., case of the bones softened and distorted, x. 313 Hot-houses, a new invented stove for, iii. 659, Cullum Hotton, Peter, m. d., on Swammerdam's Treatises, iv. 442 — virtues of the acmella in the cure of stone, &c. iv. 548 Houghton, John, account of coffee, iv. 420 Hour, of the night at sea, method of finding, ix. 664, TT t» , • Condamine Houses, see Population. Houstown, Robert, m. d., an extra-uterine fcetus, vi. 666 — cure of dropsy in the ovarium, vii. 2 — account of the contrayerva, vii. 506 — on respiration with a perforated thorax, viii. 68 Howard, Hon. C, direc. and an engine for tanning, ii. 136 — of the cultivation of saffron, ii. 423 Howard, Edward, a new fulminating mercury, xviii. 649 Howard, John, extreme cold, Nov. 22, 1763, xii. 1 14 — heat of the Bath and Bristol waters, xii. 4*9 — heat of the ground on Mount Vesuvius, xiii. 93 Howell, G., stone extract, by an apert. of the urethra, ix. 252 Howman, Roger, m. d., case of hydrophobia from the bite of a fox, iii. 133 — case of haemorrhage from the penus, vi. 674 Hoxton, Walter, unusual agitation of the needle, vii. 463 — magnetic variation from London to Maryland, viii. 330 Huber, James, m. d., a body without a gall-bladder, ix. 648 — case of a gibbosity of the sternum, ibid Hubner, Martin, on the terra tripolitana, xi. 372 Huddart, Jos., of a person who could not distinguish colours, xiv. 143 — observations on horizontal refractions, xviii. 88 Hudson, Wm., biographical notice of, xi. 6l5t Note — of the natural history of Fungi, ibid Hudson's Bay, effects of the cold at, natural history, and manners, viii. 591, Middleton — of a voyage to, and residence at, xiii. 22, Wales — description of the inhabitants, xiii. 29, Same — longitude of, xiii. 32, Same — of the dying roots at, xiii. 282, Forster — account of quadrupeds from, xiii. 326, Same ■ birds, xiii. 331, Same fishes, xiii. 410, Same Huygens, Christ., biographical account of, i. 326, . . Note — success of pendulum watches for the longitude, i. 7 -} on the use of them, 343 — improvement of optic glasses, i. 36 — observation of Saturn, at Paris, i. 326 — laws of motion on the collision of bodies, i. 335 — a halo at Paris, i. 458: cause of halos and parhelia, 458 — appearance of Saturn's ring, L 530 — observations on Newton's reflecting telescope, i. 694 — cause of mercury adhering to the top of a small tube, ii. 1 — solution of Alhazen's problem, ii. 97, 1 07 — on Hook's book respecting the earth's motion, ii. 135 — description of his portable watches, ii. 199 — pneumatical experiments, ii. 239, 257 on insects, ii. 271 — various pneumatical experiments, ii. 272 Hughes, Rev. Griffith^ description of a zoophyton, viii. 716" Huillier, Simon Le, elements of exponential quantities} and of the trigonomet. functions of circular arcs, xvii. 703 Hulme, Nath., m. d., biograp. account of, xviii. 630, Note — on the light emitted from various bodies, ibid Hume, Francis, m. n., on preserving in lime-water, fish and flesh from putrefaction, x. 358 Humfries, I , Esq., sponta. inflam. from linseed oil, xvii. 449 Humming bird, on the food of the, iii. 551, Grew Hunauld, Fran. J., m.d., biograp. account of, viii. 17, Note HUX INDEX. HYG 55 Hunauld, Fran. J., M. v., biog account of, viii. 17, Note — operation of the fistula lacrymalis, viii. 17 Hungarian bolus, see Bolus. Hungary, of the mines, minerals, &c, i. 436", .. ..Brown — copper mine at Herrngroundt, i. 450, Same — baths in Hungary, and stone quarries, ibid, Same Hunter, Christ, Roman inscriptions at Durham, iv. 514 — account of Roman inscriptions and stations, iv. 66*6 — Roman inscriptions near Lanchaster, vi. 312 at Rochester, ix, 70 Hunter, John, biographical account of, xiii. 354, * . Note — anatomy of the siren lacertina, xii. 36o — digestion of the stomach after death, xiii. 354 — anatomy of the raja torpedo, xiii. 4/8 — of receptacles for air in birds, xiii. 530 — anatomical observations on the gillaroo trout, ibid — anatomical descrip. of the gymnotus electricus, xiii. 666 — production of heat by animals and vegetables, xiii. 685 — recovery of people apparently drowned, xiv. 63 — experiments on the heat of vegetables, xiv. 278 — account of the free martin, xiv. 521 — small-pox communic. to the foetus by the mother, xiv. 628 — of an extraordinary pheasant, xiv. 723 ■ — of the organ of hearing in fishes, xv. 308 — anatomical description of a new sea animal, xvi. 4 — exper. of the effect of extirpating one ovarium on the pro- lific powers, xvi. 260 — the wolf, jackal, and dog, of similar species, xvi. 264, 562 — structure and economy of whales, xvi. 306 — natural history and economy of bees, xvii. 155 — on the crystalline humour of the eye, xvii. 344 Hunter, John, m. d., observ. on subterranean heat, xvi. 377 Hunter, Wm., M. d., biograp. account of, viii. 686, Note — structure and diseases of articulating cartilages, ibid — bones of a large animal in North America, xii. 504 — fossil bones of a quadruped at Gibraltar, xiii. 64 — accouut of the nyl-ghau[whife-footed antelope], xiii. 117 — death and dissection of Dr. Maty, xiv. 217 — new method of applying the screw, xv. 29 Hurricanes, of two in Northamptonshire, i. 593, . . Templer — at the Mauritius, iv. 297, Witzer — causes of, and prognostications of, iv. 330, .... Langford — in Huntingdonshire, viii. 530, Fuller — signs of the approach of, x. 710, Peyssonel Hutchins, T., exper. on the dipping needle, xiii. 6l3, xiv. 22 — freezing of quicksilver at Hudson's bay, xiv. 20, xv. 41 1 Hutchinson, Rev. B., a luminous arch, Feb. 1784, xvi. 630 Hutton, Charles, ll.d. on quickly converging series, xiv. 84 — demonstration of Lexel's polygonal theorems, xiv. 120 — exper. on the force of fired gunpowder, xiv. 283 — survey of the hill Schihallien to ascertain the earth's mean density, xiv. 408 — the point of greatest attraction in a hill, xiv. 603 — of cubic equations and infinite series, xiv. 704 — - a new division of the quadrant, xv. 465 Huxham, John, m. d., biograp. account of, vi. 671, Note — preternatural structure of a woman's genitals, ibid — case of a remarkably large omentum, vii. 17 — case of green saliva, vii. 19 — an anomalous small-pox at Plymouth, vii. 110 — of an aurora borealis, Oct. 1726, vii. 158 — large stone from the urethra, vii. 385 — tumour in the lumbar region of an infant, vii, 386 — a remarkal le disease of the colon, vii. 518 — an inguinal hernia, viii. 474 — an extraordinary venereal case, viii. 480 — polypi from the hearts of sailors, viii. 580 Huxham, John, r.f. o , case of the ureter grown up, ix. 87 — a beautiful stalactites, and a remarkable calculus, ibid — extraordinary tumour near the anus of a child, ix. 512 — northern lights observed Feb. 1750, x. 54 — a body buried 80 years, undecayed, x. 202 — medical and chemical observations on antimony, x. 554 — effects of lightning on a hulk at Plymouth, x. 5.60 — agitation of the waters, 1755, Devon and Cornw., x.[652 — case of a man who swallowed melted lead, x. 676 — cure of the gut ileum cut through by a knife, xi. 73 — heat of air at Lond. and Plymouth, July 1757, xi. 176 — effects of the heat of July, 1757, on the health, xi. 204 — two remarkable surgical cases, xi. 623 Hydatids, supposed a sort of worm, iii. 445, Tyson — voided with urine, iv. 601, Davies — voided by stool, v. 179. Musgrave — in a sheep's kidney, v. 315, Cowper — in a tumour of the neck, v. 332, Tyson — found in the abdomen, vi. 556, Thorpe — voided per vaginam, viii. 494 Watson — conjectures on the formation of, viii. 495 ...... Le Cat Hyde, J., earthquake, Nov., 1755, at Boston, Amer. x. 666 Hydraulics, to raise water up heights, ii. 129.. • • Moreland — description of an hydraulic engine, ii. 323 — a new hydraulic engine, iii. 193, 249, 348, Papin — remarks on Papin's engine, iii. 239, Vincent — proposal for an engine, iii. 244, Tenon — construction of water-pipes, iii. 310 — machine for raising water by fire, iv. 398, Savery — doctrine of the motion of, vi. 324, Polenus vi. 336, 595, Jurin — ascent of water in capillary tubes, vi. 330, 432, . . Same — an engine with the help of quicksil., vi. 550, Desaguliers -^ on water-pipes, and freeing them from air, vii. 137, Same — force of water through an orifice, vii. 203, Eames — of the water-works at London-bridge, vii. 442, Beighton — an engine for raising water, vii. 663, Churchman — measure and motion of effluent water, viii. 278, 2.98, Jurin — fall of water under bridges, xi. 193, Robertson — on artificial springs, xv. 627, Darwin — description of an hiero-fountain, xi. 633, Wolfe — machine for raising water, xiii. 645, Whitehurst Hydrocephalus, ace. of, & the head dissect., iv. 423, Houghton viii. 622, Baster Hydro-en terocele, singular case of, xii. 445, Le Cat Hydrology, on the laws of, xvii. 259, De Luc Hydrometer, account of Mr. Clarke's, vii. 392, Desaguliers Hydrophobia, case of, and treatment, ii. 608, Lister — from the bite of a fox, iii. 133, Howman — case of, iii . 608, Turner — account of three cases, v . 525, Mead — experiments with mercury for its cure, viii. 69, . . James — case of a boy bitten by a mad dog, viii. 113, .... Nourse — another case, viii. 205, Hartley and Sandys — use of the Tonquinese medicine for, ix. 89, Reid — horse bitten by a mad dog, x. 55, Star — case of, and body dissected, x. 245, Wilbraham — cure of, with vinegar, inquiry into the authenticity of the case, xii. 221, Earl of Morton — see Dog, (Mad.) Hydrosarcocele, extraordinary case of, xv. 345, . . Schotte Hydrops ovarii, see Ovarium. Hydrops pectoris, see Dropsy. Hygrometer, of an uncommon hygroscope, ii. 310 — a new one, ii. 346, Coniers — a new hygroscope, iii. 171, Molyneux — observations with, in 1723, vii. 2, Cruquius — a new one, ix. 35, Pickering 56 IMP INDEX. I NO Hygrometer, an improved hygroscope, ix. 214, ... . Arderon — an improvement in the weather-cord, ix. 234, .... Same — made with a deal rod, ix. 242, Same — description of a. new one, xii. 151, Ferguson xiii. 127. • • — Smeaton — ■ - xiii. 469, De Luc ■ that used by the r. s., xiv. 53, . . Cavendish — experiments with his hygrometer, xvii. 1, 111, . . De Luc Hygrometry, on the laws of, xvii. 260, De Luc Hyoscyamus albus, see Henbane Hyperbola, on the squaring of the, i. 233, Lord Brouncker — construction of a quadratrix to the, v. 302, Perks — theorem of the arc of, xiii. 647, Lander — see Geometry, Curves, Logarithms, &c. Hypnum terrestre, description of and seeding, ix. 200, Hill Hypocaust, a Roman sudatory in Shropshire, v. 29^, Lister — remarks on the hypocaust in Shropshire, v. 291, Harwood — of the hypocausts of the ancients, ibid, Baxter — description of a Roman, in Lincolnshire, viii. 532,Sympson Hysteric and hypocondriac passions, opinions of Willis and Highmore, i. 411 Ice, to preserve ice and snow with chaff, i. 50, Ball — made without air, diff. from com. ice, i. 599, Rinaldini — on the instantaneous freezing of water, vii. 223,Triewald — new experiments on ice, viii. 223, Nollet — motion and dissolution of the masses of ice in Hudson's Bay, xiii. 23, 31, Wales Ice (artificial,) method of producing ice, i. 89, Boyle — experiments of artificial conglaciation, i. 541 — — on the freezing of salt waters, iii. 107, Lister — — — on freezing, iv. 322, 340, Desmasters ■ of freezing various waters, v. 481, Hauksbee . tinctured waters, v. 483, . . Same in vacuo, vii. 22, . . . Fahrenheit — experiments on sudden freezing, ix. 93, Holman ■ - the freezing of boiled water, xiii. 6l 1, Black — process of making ice in the E. Indies, xiii. 643, Barker — experiments on the freezing of sea water, xiv. 35, Nairne — M'Nab's experiments, at Hudson's Bay, with freezing mixtures, xvi. 97, 425, Cavendish — experts, on the freezing of vitriolic acid, xvi. 271, Keir —of making ice at Benares, xvii. 294, 305,. . . . Williams — see Cold (chemistry,) Congelation. Iceland, account of, ii. 187, Biornon Ichneumon worms, account of, i. 644, . . Willoughby — of the t£»ft//*»i', i. 645, Lister Icy mountains, of Switzerland, account of, i. 365, Muraltus — of the same, v. 481, Burnet Idiot, who swallowed iron, at Ostend, v. 433, Amyand Ignis fatuus, how caused, vii. 374, Derham Ignition, increased weight of bodies by, xiv. 96, . . Roebuck — experts, on weight of ignited bodies, xiv. 1 12,Whitehurst Iliac passion, cure of the, iv. 498, Chirac — case of, ix. 124, Amyand — from palsied intestines, x. 164, De Castro Ilium, a rupture of the, viii. 138, Wolfe — cure of, cut through by a knife, x. 73, Huxham Imagination, force of, enabling old women to give suck, ii. 141 — child born with a wound in the breast, iv. 102, Cyprian -i— extraordinary effect of, iii. 37-5, Ash Imitation, of an imitative man, ii. 382, Garden Immersion, into hot and cold, fresh and salt, water, effect of, on the powers of the body, xvii. 193, Currie Impact, see Motion, (Force of Moving Bodies.) Imposthume, in the stomach, case of, vi. 579, ..Atkinson ■ liver, vii. 500, Short Imposthume, in the gall-bladder, viii. 228, Amyand ; obser- vations on the same case, viii. 232, Stuart — in the stomach of a girl, x. 29, '..'.' Layard Impregnation, modern doctrine of, i. 697 ; ii. 581, . . Notes — continued impregnation of the aphides, iv. 515,'.'. Note — animal impregnation, xviii. 112, Haighton — observations of the changes in the ova for 4 days after impregnation, xviii. 129, Cruikshank — see Generation. Incalescence, of quicksilver with gold, ii. 267 Incarville, Father, D', observations in natural history, &c. made in China, x. 387 Increments, on the method of, vi. 189, Taylor Incrustation, a remarkable sparry incrusta., xiii. 439, King Incus, see Ear. Indians, of North America, of the languages, manners, Pallas — a mass of native, found in S. America, xvi. 369, • • Celis — appearances on the conversion of cast into malleable, xvii. 47, 209, Beddoes — polarity of iron-filings, xvii. 145, Bennet — experiments on the nature of wootz, xvii. 580 . . Pearson — properties of iron in its different states, xvii. 588, . . Same — see Steel. Iron works, in the forest of Dean, ii. 418, Powle — in Lancashire, iii. 523 Sturdy Irritability of animal fibres, experts, on, x. 6 13, Brocklesby Irreducible case, see Cardan. Ironside, Lieut. Col. culture and uses of the sun-plant of Hindostan, xiii. 505 — manufacture of paper from the sun-plant, xiii. 506 Ischia, the volcanic origin of, xii. 593, Hamilton Isinglass, method of manufacturing, xiii. 36l, . . . .Jackson Island, a new raised, in the Archipelago, v. 407, • • • • Sherard — a new volcanic, near Santorini, v. 446,. . . . Bourgignon — of the same, and phenomena attending it, v. 647, Goree — sunk, recovered from the sea, vi. 423, . . Chamberlayne — a new volcanic, near Tercera, vi. 584, Forster — on the formation of islands, xii. 454, Dairymple Isle, Jos. N. de, see Delisle. Isnard, Mons., management of silk- worms, i. 30 Isoperimetrical probl., resolution of, x. 560, xi. 238, Simpson Isthmus, remarks on the probable existence, formerly, of one between Calais and Dover, iv. 6l 8, 637, Wallis — inquiry on the same subject, vi. 293, Musgrave Istria, observations in a tour through, ii. 284 Vernon Italy, state of learning in, iv. 506, Silvestre — remarks on a tour through, x. 52, More Itch, of the animalcula which produce it, v. 1, , Mead Ivory, microscopical observations on, ii. 438, . . Leuwenhoek Jackal, similarity, in species, to the wolf and dog, xvi. 562, Hunter Jackman, Rev. J., on the rule for finding Easter, v. 250 Jackson, Humphrey, biog. account of, xiii. 362, . . Note — method of making isinglass, ibid Jackson, Wm., m. d., way of making salt, and description of the springs at Nantwich, i. 397, 405 Jacob, Mr., elephant's bones in the Isle of Shepey, x. 489 Jaculator Fish, [chaetodon rostratus] desc, xii. 110,Schlosser account of, xii. 321, Hommel Jamaica, of the alligators at ; tortoises ; chegoes ; shining flies j manchenille apple, &c. i. 295, Norwood — of a hot mineral spring at, iv. 79 Beeston — of several plants of, iv. 362, Sloane — observations on natural history of, vi. 368, .... Barham — longitude of Port-Royal, vi. 6l9, Halley — temperature of springs and wells at, xvi. 377,. . Hunter James, Rob., m. d., biographical account of, viii. 69, Note — experiments with mercury for cure of mad dogs, ibid Jamineau, Isaac, eruption of Vesuvius, 1754, x. 563 James's powder, analytical exper. on, xvii. 87,. . . . Pearson Japan, natural history, arts, manners, &c. of, i. 365 — method of curing several diseases, ii. 633 — journal of a residence at, xiv. 634, Thunberg Japan-varnish, manufacture and use of, iv. 299 Jardine, Lieut., transit of Venus and solar eclipse, 1769, Gibraltar, xii. 657 Jartoux, Father, description and virtues of ginseng, vi. 56 Jasper, result of an experiment of melting, i. 620,. . Becher Java, sexual intercourse at an early age at, iv. 298 Jaundice, case of, which affected the vision, iii. 652, Briggs — by a stone obstructing the bil. duct, v. 292, . . Musgrave — communicated in coitu, ix. 686, Cooke Jaw, loss of part of the bone supplied by a callus, viii. 326, Sherman — locked jaw after a slight contusion, xii 201,Woolcombe — locked jaw cured by electricity, xii. 391, Spry Jeake, Samuel, elements of shorthand, ix. 5l6 Jeaurat, Mr., descrip. of an iconantidiptic telescope, xiv. 501 Jenkins, Hen., aged 169 years, account of, iv. 92, Robinson — on the great age of, iv. 167, Hill Jenkins, Samuel, machine for grinding lenses, viii. 451 Jenner, Edward, m. d , nat. hist, of the cuckoo, xvi. 432 Jenty, Nich., case of the cohesion of the intestines, xi. 215 Jernegan, Charles, m. d., cystis of water in the liver, ix. 108 Jessamine, change of colour in the blossom of, vi. 489, Cane Jessop, Mr., different sorts of damps, ii. 224 — extraordinary worms voided at the mouthy ii. 225 — remarks on fairy circles, ibid — on damps of mines, ii. 244 Jessop's Well, virtues of the water, x. 48, ......... Hales Jesuits, succesion of earthquakes at Brigue, x. 707 — solar eclipse, 1764, at Rome, xii. 150 Johannes, F., medicin. virtues of the ignatia amara, iv. 356 Johnson, Mau., earthquake at Scarborough, 1737, viii. 514 — a new metalline thermometer, ix. 459 Johnson, Sir Wm., of the languages, manners, &c. of the North American Indians, xiii. 407 Johnston, — , M. d., of gold colour, stones in the blad. ii. 125 Johnstone, James, m. d., biog. account of, xi. 211,. .Note — two extraordinary cases of gall-stones, ibid — on the use of the ganglions of the nerves, xii. 123, xiii. 8 — of a foetus with an imperfect brain, xii. 404 Johnstone, , m. v., of the earthquake of 1795 as felt at Worcester, xviii. 31 Jointed worm, see Lumbricus hit us. JUP INDEX. KER 59 Joints, of a man* who had the power of dislocating, and replacing them at pleasure, iv. 294 Jones, Rev. Hugh, account of Maryland, iv. 46 1 Jones, Jezreel, food of the moors of Barbary, iv. 407 Jones, Thomas, a high tide in the Thames, 17267 vii. 133; 1736, viii. 59 Jones, "William, biographical account of, ix. 357, Note : — equations of goniometrical lines, ibid — construction ■ of logarithms, xiii. 190 — effects of lightning on Tottenham-court chapel, xiii. 307 — on the conic sections, xiii. 458 Jones, Sir Wm., catalogue of Sanscrita mss., xviii. 427 Oriental mss., xviii. 56*3 Journal, of a voyage to the East Indies, method of, xiv. 386, Dalrymple Journeys, see Voyages. Judda, observations on a voyage to, xiii. 287>. • . . Newland Jugulars, mercury injected into the, iv. 273,. . . . Musgrave Juices, of plants, on the nature and differ, of, iv. 123, Lister — see Sap. Julian Period, M. de Billy's method of rinding, i. 121 ; demonstrated by Mr. John Collins, i. 207 Jupiter, observation of a spot in one of the belts of, i. 3 — discovery of the spot claimed by Divini, i. 68 — one of the satellites passing over it, i. 52 — of a permanent spot, showing that this planet moves round its own axis, i. 52 — rotation of, on its own axis, i. 60, .... Hook and Cassini — observation of, i. 83, Hook — observations of the spots in, and cause, i. 706, Cassini ; calculation of the rotation, ibid. — inclination of, to the ecliptic, ii. 65, — occulted by the moon, June, 1679, ii. 480, . ii. 481, Flamsteed . Hevelius . . . Cassini Flamsteed . Hevelius — observ. of conjunctions with Saturn, ii. 637,. — 3 conjunctions with Saturn, 1682-3, ii. 662, — two eclipses of, by the moon, 1686, iii. 294, Hook, &c. — eclipsed by the moon, 1686, Dantzic, iii. 331, Hevelius „ . ■ iii. 326, Flamsteed — occultation by the moon, 1715, vi. 212, Pound — occultation of a star in Gemini by, vi. 271 — and his satellites occulted by the moon, viii. 477, Bevis — occultation by the moon, London, 1744, ix. 45, ... Same — conjunction with Venus, Pekin, 1748, x. 22, Hallerstein Jupiter's satellites, Auzout's opinion respecting, i. 25 <— one of the satellites passing over the planet, i. 41 — occultation of the first satellite, i. 658, Hevelius — configuration of, and predictions, ii. 324, Cassini — eclipses and ingresses of, 1683, ii. 660, Flamsteed — calculation of eclipses for 16'84, ii. 6?9> Same — calculations of eclipses verified, iii. 234, Same . instrum. to find the dist. of, from his axis, iii. 246, Same calculation of eclipses of the first satellite, iii. 672 emer. of the first from Jupiter's shadow, vi. 92, Bianchini — transit of the fourth over Jupiter's disk, vi. 386,. . Pound — observations with reflecting telescopes, vi. 665, . . Hadley — eclipse of the first satellite at New York, vii. 49, Burnet ______ . . > Lisbon, vii. 55, . . Carbone — immersions and emersions observed, vii. 132, Lynn — eclipses of the first satellite, at Lisbon, vii. 141, Bradley — vii. 143, Carbone « 1 Toulon, vii. 144, . . . Laval — eclipses observed at Rome, vii. 165, Bianchini ■ Bologna, vii. 265, Manfredi . Pekin, vii. 273, Kogler ■ Ingolstadt, vii. 274 Pekin, 1727, 1728, vii. 418 — occulted by the moon, 1740, viii. 477, Bevis Jupiter's satellites, eclipses observed at Pekin, x. 3, Gaubil Lisbon, x. 567 ; xi. 158, Chevalier — observations of the eclipses of, recommended to be made by the French astronomers, xi. 520, Maskelyne — tables of the motions of, xi. 535, Dunthorne — problem respecting the duration of the shadow of the eclipses of, xii. 372, . / WitcheU — eclipses of the 1st observed at Glasgow, xii. 670, Wilson ; compar. observ. at Greenwich, xii. 671, Maskelyne — eclipses of the 1st satellite, at Funchal, xiii. 82, Heberden — on perfecting the theory of, xiii. 422, Bailly ; Notes on Mr. Bailly's paper, xiii. 430, Horsley — eclipses of, observed near Quebec, xiii. 526,. . . . Holland ' at Gaspel, ibid, Sproule North America, xiii. 527, Holland — comparison of observations at Greenwich, with those at North America, xiii. 527, Maskelyne — eclipses of the 1st satellite at Anticosti, xiii. 528, Wright — of their changeable brightness, rotation, and diameters, xviii. 187, Herschel Jurin, James, m. d., biographical account of, vi. 330, Note — ascent of water in capillary tubes, ibid, and 432 — doctrine of the motion of running water, vi. 336, 595 — Roman inscription near Carlisle, vi. 362 — muscular motion of the heart, vi. 375 ; reply to Keill's epistle on the same subject, 427 — specific gravity of human blood, vi. 415 — on examining the specific gravity of solids, vi. 538 — on the infection of small-pox, vi. 601 — tables of the mortality of small-pox, vi. 6l0 — on making of meteorological observations, vi. 676 — measure and motion of effluent water, viii. 278, 298 — theory of the action of springs, ix. 18 — force of moving bodies, ix. 128 — dynamical principles, ix. 217 Justel, — — , an engine for consuming smoke, iii. 292 — an extraord. swarm of grasshoppers in Languedoc, iii. 3 19 — an ancient sepulchre in France, iii. 337 K Kanguroo, organs of generation and mode, xvii. 535, Home Kapanhihane, description of the bog of, iv. 206, Molyneux Kay, Jonathan, of an extraordinary cancer, iv. 643 Kearsly, Dr., of the comet of 1737, Philadelphia, viii. 153 solar eclipse, viii. 154 Keill, James, m. d., biographical account of, v. 299> Note — dissection of a man at 130 years old, ibid — on the propulsive force of the heart, vi. 415 Keill. John, m. d„ biographical account of, v. 417, - • Note — laws of attraction, ibid - centripetal force, v. 435 — solution of Kepler's problem of the planets' motion, vi.l — theorems on the divisibility of matter, vi. 91 — inverse problem of centripetal forces, vi. 93 Keir, James, m. d., on the crystallizations on glass, xiv. 102 Keir, James, the freezing of vitriolic acid, xvi. 271 — dissolution of metals in acids, xvi. 695 Kelly, James, strata found in digging for mad, vii. 154 — fossil horns found in Ireland, ibid Kelp, how produced, ii. 459, » • • Colwall Kepler, John, biographical account of, ii. 130, Note — of his manuscripts, ii. 132, Hevelius — solution of his prob. on the planets' motion, vi.l, Keill; viii. 177, Machin Kermes, grain of, its use, and preparation, i. 134, Verny — insect husks of, on plum-trees, i. 598, 607. ii. 7, Lister Kerkringius, — , m.d., on eggs in all sorts of females, i. 6^7 H2 (jo KLE INDEX. LAM Kerr, James, natural history of the coccus lacca, xv. 125 Kersseboom, Wm., on the probable duration of life, x. 383 Kidneys, observations on the, i. 324, iii. 49, . . . .Malpighi — calculous concretions, i. 594, Kirkby — strange conjunction of, ii. 449* Tyson *— of a shell in a woman's kidney, iii. 168, Peirce — case of a diseased kidney, iv. 105, Cowper — case of an ulcer in the kidney, v. 554, Douglas Kies, M. solar eclipse, 1750, Berlin, x. 9 Kilbum-wells water, analysis of, xviii. 149, • • • • Schmeisser Kilcorney Cave, see Caverns. Kilpairick, Sir Thos., agitation of waters at Closeburn, x. 6*92 Kinck, Peter, account of the Finlanders, vii. 210 King,. Charles, of stones in crawfish, iv. 519 King (Sir Edm., m. d.) on the parenchymatous parts of the body, i. 119 — of the different sorts of ants, i. 151 — experiments on the transfusion of blood, i. 158 — - remarks and experiments on the testicles, i. 392 — of insects found in old willows, i. 532 — of a petrified glandula pinealis, iii. 340 — animalcula in pepper water, iii. 569 King, Edw., biographical account of, xiii. 137, ....Note — theory of the universal deluge, xii. 379 — formation of spars and crystals, xii. 384 — description of the cancer stagnalis, xii. 390 — account of Elden Hole, Derbyshire, xiii. 137 — effects of lightning at Steeple-ashton and Holt, xiii. 435 — of a remarkable sparry incrustation, xiii. 439 — a petrifaction found on the Scotch coast, xiv. 478 King, Wm., of the bogs and lakes in Ireland, iii. 141 Kinnier, D., m. d., of camphor in maniacal disorders, vii.206 Kinnersley, Ebenezer, electrical experiments, xi. 702 — electrical properties of charcoal, xiii. 370 Kirch, Christ., Aldebaran occulted by the moon, viii. 358 — observations of Mars, 1736, viii. 457 Kirch, Godf, comet of l6S0 observed at Cobourg, vi. 114 — new star in the swan's neck, vi. 153 — observation of a comet at Berlin, 1718, vi. 363, 621 — eclipse of the sun, Berlin, Feb. 1718, vi. 363 — Venus eclipsed by the moon, vii. 385 Kircher's " Mundus Subterraneus," account of, i. 40 Kircher, Athanasius, biographical notice of, i. 40, . . Note — a preparation for staining marble throughout, i. 44 Kirkby, C, of stones in the kidney ; and the lungs, i. 594 — of a green poisonous substance arising on a lake near Dantzic, and of a white amber from the same lake, i. 721 — effect of thunder and lightning on grain, ii. 89. — an uncommon case of sickness, ii. 90 — of 38 stones in a bladder, ii. 115 Kirkbythore, antiquities in a well at, iii. 25, .... Machel Kirke, Thos., of a lamb suckled by a wether, iii. 678 Kirkshaw, Rev. S., d. d., pigs of lead with Roman inscrip- tion, viii. 453 — fatal effects of lightning at Leeds, xiii. 420 Kirwan, Richard, specific gravities and attractive powers of some saline bodies, xv. 3, 236 — on Mr. Cavendish's experiments on air, xv. 502, 514 — on specific gravities at different temperatures, xv. 696 — experiments on sulphuretted hydrogen gas, xvi. 68 Klein, J. Theod., worms in the kidneys of wolves, vii. 389 — a fossil skull of an ox, vii. 571 — of a plica polonica, vii. 572 — remarkable swelled eye, ibid — account of the flying squirrel, vii. 588 — of the vespertilio bontii [lemur volans] ibid — description of the monoculus apus, Linn., viii. l6l Klein, J.Theo., letters found in the middle ofa beech, viii. 359 — remarks on a gigantic bregma, viii. 388 — antiquities found in Prussia, viii. 420 — on Le Bruyn's account of petrified oysters, viii. 455 — natural history of the marmot, ix. 472 Klingenstiern, Sam., quadrature of hyperb. curves vii. 462 — aberration of refracted light, xi. 514 Klinkenberg, D., comet of 1757, at the Hague, xi. 190 Knapton, George, articles found at Herculaneum, viii. 437 Knee, an extraordinary tumour in the, viii. 294, .... Peirce — successful treatment of diseased joints, x. 671, . . Warner Knight, Gowin, m. d., magnetical experiments, ix. 71, 390 — magnetic poles variously placed, ix. 122 — effect of lightning on the compass, ix. 653 — description of his mariner's compass, x. 64 — effects of lightning on metals, xi. 394 — magnetic machine, account of, xiv. 117, .... Fothergill Knight, Thomas, of hair voided with the urine, viii. 491 Knight, Tho. And., on the grafting of trees, xvii. 569 — on the fecundation of vegetables, xviii. 504 Knowlton, Tho., scite of the ancient Delgovitia, ix. 216 — of men of extraordinary weight, ibid — extraordinary deers' horns, ix. 225 Koegler, Ignatius, astronomical observ. at Pekin, vii. 273 Konig, Sigism., m.d., remark, case of calcali, ii. 510, iii. 298 Krashennikoff, Prof, account of the part of America bor- dering on Kamt&chatka, xi. 432 Krate, Christ., account of a monstrous child, iii. 48 Krieg, D., m. d., prepar. of cobalt, smalt, and arsenic, v. 165 Kuckahn, T. S., method of preserving dead birds, xiii. 50 Kunkel, John, biographical account of, ii. 489, .... Note — account of his phosphorus, ibid, Sturm — chemical controversy with Dr. Voight, iii. 125 Labradore, Nat. Hist, and inhabitants of, xiii. 547, . . Curtis — meteorological journals at, xiv. 597, xv. 87, De la Trobe Lac, (gum) phosphoric quality of, v. 408, ......... Wall — of the insect producing it, and its uses, xv. 125, . . Kerr — of the insect producing it, in Thibet, xvi. 554, Saunders — experts, on white lac collect, at Madras, viii. 428, Pearson — nat. hist, and description of the chermes lacca, xviii. 62, Roxburgh Lacerta aquatica, circulation of blood in, iii. 238, Molyneux — slips off the skin like serpents, ix. 349, Baker Lacrymae Batavicae, or glass drops, phenomena of, ix. 675, Le Cat Lacteals, on the passage of chyle through, ii. 75, 554, Lister — on the passage of liquors through, iii. 102, ..Musgrave — of powder-blue passing through, iv. 570, Lister — experts, of injecting a blue liquor, iv. 632, . . Musgrave — salt of steel will not pass through, xi. 229, Wright Lafage, John, aneurism of the arteria aorta, iv. 526 — dissection ofa dropsical body, v. 219 Lagopus, see Ptarmigan. Lake, peculiarities ofa lake in Mexico, ii. 357 — peculiar freezing of some lakes, ii. 211, Mackenzy — of the Wetteu in Sweden, v. 207, Heme — Malholm Tarn in Yorkshire, viii. 46'3, Fuller — see Loch Ness. Lalande, Jerome de, notice of his death, xii. 663, .... Note — transit of Venus, 176!, xi. 562 — on Norwood's measurem. of a deg. on the merid. xi. 594 — observation of the comet of 1762 at Paris, xi. 645 — transit of Venus 1769. observed in France, xii. 663 — letter from Paris on astronomical observations, xi. 648 Lamas, experts, on the poison of, x. 144, Herissant LAT INDEX. LEG 61 Lamas, further account of the poison of, x. 145, .... Note ] Lambert, James, effect of lightning on a bullock, xiv. 90 Lamps, a newly invented lamp, ii. 498, Beyle — sepulchral lamps of the ancients, iii. 100 Plott — an invention for preserving the wick, iv. 321, . . St. Clair — superiority of Argand's to the common sort, xvii. 370 ; to candles, 371 Lana, F., on a burning-glass melting iron sooner than gold, i. 672 ; a chemical experiment, ibid — on crystals exhaled from the ground, i. 720 — of a flying ship, ii. 478 Lancisi, John Maria, biographical account of, iv. 151, Note — account of the death and dissection of Malpighi, ibid — remarks on Vieussen's experiments on blood, iv. 503 Land, see Manure. Land-carriage, see Carriage. Landaff, Bishop of, see Watson, Rich. D. D. Lande, Jerome de la, see Lalande. Landen, John, biographical account of, x. 469, Note — properties of the circle, ibid — on the sums of certain series, xi. 441 — new method of comparing curved areas, xii. 544 — new theorems for areas of curves, xiii. 77 — disquisition on certain fluents, xiii. 150 — theorem of the hyperbolic arc, xiii. 647 — new theory of rotatory motion, xiv. 144 — on rotatory motion, xv. 703 Landerbeck, Nich., on finding curve lines, xv. 456, 627 Lane, Thos., a new electrometer, xii. 475 — solubility of iron by fixed air, xii. 633 Langelot, Joel, M. d., on digestion, fermentation, &c. ii. 7 Langford, Capt., causes and prognost. of hurricanes.iv.330 Langrish, Browne, application of receivers to retorts, ix. 96 Language, origin of, ii. 308 — connection of the Chinese and Egyptian, xii, 685 — account of the Romansh, xiv. 7, Planta Languedoc, canal of, i. 418, 723 — extraordinary swarm of locusts in, iii. 319 Langwith, Benj. d.d., a rainbow seen on the ground, vi. 541 — a sort of secondary rainbow, vi. 623 — observations on the figures of snow, vi. 64-5 — of an aurora borealis, Oct. 1726, vii. 157 Lapis Calaminaris, see Calamine. Lark, a species from Hudson's bay, xiii. 338, .... Forster Larum, (alarm) descrip. of the weaver's, ix.180, . . Arderon Laryngotomy, advan. of the practice of, iv. 448,. . Musgrave Latham, Rev.Eben. an improv.of the celest. globe, viii. 176 — on the ancient sphere, viii. 501 — position of the colure in the ancient sphere, viii. 607 Latham, John, earthquake at Lisbon, 1755, x. 659 — a periodical fever, and separation of the cuticle, xiii. 78 — remarkable case of dropsy, xiv. 481 Latham, Wm., singular instance of atmos. refrac. xviii. 337 Latitude observ., of, from Java to St. Helena, vii. 552, Halley — inst. for taking, at any time of the day, vii. 6*73, Graham — a place at New York for measuring a degree of, viii. 419, Alexander — observations of at Churchill river, viii. 597, . . Middleton — 3 deg. of, under the merid. of Vienna, xii. 497,Liesganig — observations for a degree of, in Maryland and Pennsyl- vania, xii. 566, Mason and Dixon ; remarks intro- ductory by Dr. Maskelyne, 564 — length of a degree, deduced from the observations of Messrs, Mason and Dixon, xii, 573, Maskelyne — to find a lat. by two altitudes of the sun, xviiii 466, Lax Latitude (of places) of Constantinople, iii. 255, . . Greaves — of Rhodes, iii. 257, Same Latitude (of places) some principal places in Russia, iii. 422, Timmermari — -Pekin, iv. 233, Cassini — Lisbon, vii. 143, Carbone — Toulon, vii. 1 44, Laval — Vera Cruz, vii. 224, Harris — Aleppo, Mount Cassius, Seleucia, Antioch, Diarbekir, Bagdad, x. 6l8, Porter — of New York, viii. 420, Alexander — of the Cape of Good Hope, xi. 596, Mason — of the Jesuit's observatory, Vienna, xii. 220, . . Liesganig — islands of St. John and Cape Breton, xii. 507,. . Holland — Churchill factory, Hudson's bay, xiii. 31, Wales — Stamford in Lincolnshire, xiii. 131, Barker — King George's island, xiii. 175, Green and Cook — Judda and Mocha, xiii. 289, . Newland — Leicester, xiii. 665, Ludlam — Brussels and Louvain, xiv. 401, Pigott — Cork, xiv. 511, Longfield — Madras, xiv. 512, Stevens — York, xvi. 145, Pigott — the observatory, Greenwich,, xvi. 221, .... Maskelyne Paris, xvi. 229, Same — some places near the Severn, xvi. 709, Pigott in Denmark, xvii. 353, Bugge Latterman, Jas., effects of vegetable styptics, x. 566 Laudanum, Van Helmont's preparation of, ii. 157, . . Boyle Laurel water, poisonous quality of, vii. 468, Madden vii. 495, .... Mortime* viii. 297, •• Rutty Lauro-cerasus, experts, on the poison of, xiv.. 66l, Fontana Laval, Father, celestial observations at Toulon, vii. 144 Lavington, — m. d., bad effects of sea- water, as an internal medicine, to certain constitutions, xii. 177 Lawrence, Thos , m. d., effects of lightn. in Essex-st.xii.144 Lax, Rev. W., lat. by two altitudes of the sun, xviii. 466 Layard, Dan. P. m. d., fracture of the os ilium, ix. 173 — extraordinary imposthurae in the stomach, x. 29 — utility of inoculating for the distemper of cattle, xi. 206 — extraordinary disease of the eye, xi. 274 — analysis of the Somersham mineral water, xii. 275 — nature of the distemper of horned cattle, xiv. 723 Lead, account of the Mendip mines, i. 186, 276, . . Glanvil — experiment on the cohesion of, vii. 100, .... Desaguliers. — account of the mines in Derbyshire, vii. 333, . . Martyn — case of a man who swallowed melted lead, x. 673, Spry ' x. 676, Huxham — native lead found in Monmouthshire, xiii. 369, . . Morris — analysis of the molybdate of lead, xviii. 4, .... Hatchett — see Black-lead, Cerusse. Lead-ore, of a peculiar sort, in Germany, i. 6 Learning, of the ancients and moderns, iii. 678, . . Wotton — state of among Greeks and Turks, 1755, x. 583, Parsons Leather, manner of dressing in Turkey, ii. 62 — see Tanning. Leaves, of the veins, &c. in, vii. 419, Nieholls Lee, Arthur, m. d., experts, on the Peruvian bark, xii. 290 Leech, anatomy of the, iv. 209, Poupart — account of the sea-leech, vii. 424, Garcin Leeds, John, transit of Venus, 1769, in Maryland, xii. 67 & Legge, Honorable Edw., lunar eclipse, at Brasil, viii. 548 Legion., account of the Roman, vi. 17, Musgrave Leibnitz, G. W.. m. d., biograph. account of, i. 6l3, Note — description of his portable watches, ii. 203 — on the pursuit of philosophical studies, iv. 41 2 — solution of his problem on curves, vi. 309, .... Taylor Leigh, Charles, m. d,, biographical notice, iii. 602, ..Note LEU INDEX. LEW Leigh, Chas., m.d., description and qualities of nitre, III- 51 — theory of digestion, iii. 69 — of some strange epileptic fits, iv. 679 — a water-level for Davies's quadrant, viii. 26*0 — a mercurial-level for the same, viii. 262 Leland's Itinerary, correction of an error in, vi. 364, . . Gale L'Emery, Nichs., biographical account of, iii. 221, . . Note Lens, a lens of a drop of water, iv. 166, Gray — combina. of lenses with inclined planes, viii. 54, Hadley — machine for grinding spherical, viii. 451, Jenkins L'Epinasse, C, apparatus for electrical experiments, xii. 41 6 Leprosy, a sort at Gaudaloupe, xi. 74, Peyssonel Leprotti, Antonio, calculus voided by urine, viii. 653 Letters (Antiquities) see Inscriptions. Letters (nat. hist.) impres. by nature in a boy's eye, v. 51, Ellis — found in the middle of a beech, viii. 359, Klein — found in trees, on the cause of, viii. 36l, .... Mortimer Lettsom, J. Coakley, m. d., an extraordinary introsusception, xvi. 119 Leuwenhoek, Ant. Van, biograph. account of, ii. 66, Note — microscopical observations on insects, ii. 66, 05 — on the compression of air, ii. 128 — various microscopical observations, ii. 128 ' on blood, milk, bones, brain, skin, ii. 149 " sweat, fat, tears, ii. 151 the eye, aquatic animalcula, ii. 166 — optic nerve, blood, ii . 222 — on the texture of trees, ii. 312 ; his observations com- pared with those of Dr. Grew, ibid, Note — of animalcula in wine, ii. 3l6 — animalcula in different sorts of water, ii. 374, 383 — on muscles, brain, cotton, &c,, ii. 401 — teeth, ivory, hair, ii. 438 — animalcula in semine humano, ii. 45 1 ■ in semine animalium, ii. 473 — liquid globules, and semen of insects, ii. 507 — hair, excrements, &c, ii. 521 — muscles, fins, and shell of oysters, ii. 536 — muscles of lobsters, &c, ii. 543 — on generation, and muscles of insects, ii. 580 — structure of various sorts of wood, ii. 619 — generation of frogs, animalcula in sem. masc , &c, ii. 664 — animalcula in the teeth and scales of the skin, iii. 36 — scales in the mouth, slime in the guts, &c, iii. 43 — crystalline humour of the eye, iii. 91 — brain, chalk-stones, leprosy, scales of eels, &c, iii. 122 — figures of salts from wines, &c, iii. 146 - — salts from mineral and other substances, iii. 186 — generation by animalcula in semine, iii. 199 — semen of a rat, muscles, &c, iii. 481 — animalcula on the teeth, skin, &c, iii. 503 — on the seeds and propagation of plants, iii. 525 — experiments on cinnabar and gunpowder, iii. 537 ■ on bones, bark, scales of skin, &c. iii. 56l — on the seeds of several plants ; skin and pores of the hand; crystalline humour; optic nerve, gall offish, &c, iii. 589 — account of the wolf-insect j insects in rain water, iii. 660 — difference of timber felled at different times, iii. 672 — on eels, mites, seeds of figs, &c, iv. 94 — on eggs of snails, iv. 223 — the eyes of beetles, iv. 268 — on objections to his theory of generation, iv. 412 — on animalcula in semine humano, iv. 419 — circulation of the blood in tadpoles, iv. 464 — worms in sheep's livers, animalcula of frogs, &c, iv. 477 — circulation of blood in butts, iv. 491 — of worms from the teeth, iv. 509 — of insects from fruit-trees, iv. 5 14 Leuwenhoek, Ant. Van.,animalc. in sem. masc, iv.541,66s — on insects in willow trees, iv. 557 — observations on the spawn of cod-fish, iv. 570 spiders, their economy, &c , iv. 587 — on the tastes of water, edges of razors, iv. 601, v. 542 — remarks on microscopic observations, iv. 602 — animalc. in sem. masculino ; on shortness of breath, iv.66S — of water weeds and animalcula, v. 6, 52, 175, vi. 42 — on the solution of silver, &c. v. 52 — on the seeds of oranges, &c, v. 6l — of worms in sheeps' livers, and in pasture-fields, v. 87 — of a storm of salt rain, v. 93 — figures of various sorts of sand, v. 94 — on cochineal, and the insect, v. 140 — on the flesh and eye of the whale, v. 1 55 — on the tubes of aloe -leaves, v . 157 — salt from tobacco ashes, v. 162 — of fossil shells of Switzerland, v. 169 — on the black stains from dissolved silver, v. 1 78 — texture and growth of the bark of trees, v. 1 88 — salts of calcined hay, v. 193 — on the seeds and seed-vessels of fern, v. 197 — on the figures of crystal, v. 204 — on pumice stone, coral, sponges, v. 266 — on the seeds of some East India plants, v. 281 — structure of the spleen, proboscis of fleas, v. 315 — on pearls, oyster-shells, &c, v. 366 — on Peruvian bark, v. 372 — the whiteness of the tongue in fevers, v. 374, 449 — blood vessels and membranes of the intestines, v. 403 — structure of the tongue, v. 424 — on red coral, v. 426 — circulation of blood in fishes, v. 46 1 — on the palates of oxen, &c, v. 481 — on a bunch of hair voided by urine, v. 519 — crystals of sugar ; blood of eels, v. 530 — configuration of diamonds, v. 537 — on the edge of razors, v. 542 — crystal of silver, v. 549 — animalcula in the semen of rams, v. 640 — production of mites, &c., v. 660 — seminal vessels, blood, &c, of whales, v. 672 — contexture of the skin of elephants, v. 699 — muscles and the manner of production, v. 703 — texture of the muscular fibres, vi. 80 — on the bones and periostseum, vi. 484 — membranes of muscular fibres, vi. 502 — fibres of wood ; muscles of animals, vi. 504, 576 — muscular fibres of fish, vi. 523 — on the seeds of plants, vi. 527 — pores of box-leaves, down of peaches, &c, vi. 541 — magnetism of iron, vi. 576 — particles of fat, vi. 583 — foetus, and parts of generation, of a sheep, vi. 593 — callus of the hands and feet, vi. 594 — particles and structure of diamonds, vi. 605 — magnitude of blood-globules, vi. 660, 677 — on the structure of the diaphragm, vi. 667 Levels, an instrument for taking, vii. 51, Desaguhers Lever, on the fundamental property of the, xvii. 348, Vince Lewis, Mr., to graft fruit-trees upon bits of the root, 11. 79 Lewis, Rev. George, on some Indian mss., iv. 334 Lewis, Rev. John, of the Holt mineral waters, vii. 253, 338 Lewis, Richard, aurora borealis in Maryland, vii. 464 — insects generated in the leaves of a tree, vii. 6l4 — earthquake in America, 1732, vii. 6l5 — of an explosion in the air, ibid Lewis, Wm., literary productions of. x. 495, ...... Note LIG INDEX. LIG 63 Lewis, Wm., analytical experiments of platina, xi. 97, ibid Lexel, I. A., <* and y tauri occulted by the moon, xiii. 646 — theorem for the solution of polygons, xiii. 647 — periodic time of the comet of 1770, xiv. 485 Leyden, on the epidemic at, in 16*69, i- 6l3, Sylvius Leyden bottle, see Electricity. Ley el, Adam, a dead body preserved in a copper mine, vii. 41 Lhwyd, Edward, of a fiery exhalation in "Wales, iii. 67 1 — uncommon hail-storm in Monmouthshire, iv. 173 — several figured stones in Wales, iv. 300 — of a figured fossil stone found in Wales, iv. 381 — difference in fossils of different countries, v. 123 — large stones voided per urethram, v. 182 — observ. on the natural history of Wales, v. 676, 677, 693 — antiquities and natural history of Ireland, v. 674, 700 — of plants growing in Cornwall, v. 702 — natural history of Wales and Scotland, vi. 19, 73 Libella [libellula,] description of the, iv. 519, .. . Poupart — of Pennsylvania, description of, x. 4, 28, Bartram — see May Fly. Lichen, history of plants of this genus, xi. 246, . . . Watson Liege, mineral of, sulphur and vitriol extracted from, i. 17 Liesganig, Father, astronomical observ. at Vienna, xii. 220 — measurement of the meridian at Vienna, xii. 497 Life, on the probable duration of, x. 383, Kersseboom — on a table of the probabilities of, x. 598, . Braikenridge — - differ, duration of, in towns and villages, xiii. 679, Price — chance of, from infancy to 26 years, xv. 1 22, .... Bland — see Annuities, Reversions. Light (in general) on the motion of, ii. 397* Romer — • on that produced by inflammation, xiv. <)^, .... Fordyce — of bodies in combustion, xv. 668, Morgan — on the comparative intensity of light from different lu- minous bodies, xvii. 359, Rumford — comparative production of light by wax, tallow, and oils, xvii. 373, , Same — on the chemical properties of, xviii. 378, Same — produc. of, by heat & attrition, xvii. 128, 2 15, Wedgwood — on the light spontaneously emitted from various bodies, xviii. 630, Hulme — analogy between sound and light, xviii. 604, .... Young — on the similarity in the nature of light and heat, xviii.692, 748, Herschel Light (meteoric) a glade of, observ. in the Heavens, v. 288, Derham — a pyramidal appearance in the Heavens, v. 354, . . Same — of a remarkable lumen boreale, v. 486, Derham ' — extraordinary lights in the air, vi. 213, 226, .... Halley luminousness in the air at Dublin, vi. 455, Percival — a glade of light, March, 1735, viii. 404, Bevis — red lights, Dec, 1737, at Naples, viii. 457, Pr. of Cassano , ■ ■ Padua, viii. 458, Poleni ___——. Bononia, viii. 459* • • • Zanotti , — — Rome, viii. 460, Revillas _ — ■ ■ Edinburgh, ibid, Short „_ — • Sussex, viii. 46l, Fuller remarkable gleam from the sun, ix. 337, Collinson northern lights observed Feb., 1750, x. 54, . . . Huxham — a luminous appearance in the Heavens, xv. 114, Cavallo — observation of some luminous arches, xvi. 627, .... Hey — a luminous arch, Feb., 23, 1784, xvi. 630, . . Wollaston mm. . ibid, Hutchinson . . ■ xvi. 631, . . . Franklin hi '■ ' ibid, Pigott . — height of the arch seen Feb., 1784, xvi. 645, Cavendish — see Meteors, Aurora Boi ealis, &c. Light, (natural history,) on the luminousness of the waters in the Indian seas, vi. 53, Bourzes Light, (electrical,) product, of thro' metal, v. 645, Hauksbec — from amber, diamonds, gum lac, v. 408, Wall — see Electricity, Phosphorus, Attrition. Light, (optics,) on the doctrine of, and of colours, i. 676, Grimaldi — and colours, experts, for his theory of, i. 678, Newton — propossals of experts, for Newton, & experts, made, i.714 — animadversions on Newton's theory, i. 726, .... Parches — Newton's reply to the above, 1. 730 — queries for experiments on his theory of light, i. 73 t — 2d letter of Pardies, i. 738 ; Newton's answer, 740 — support of his theory against Hook, ii. 13 — objections to Newton's theory, ii. 85, 94 ; reply 86, 91 — and colours, nature of, ii. 146, Mayo — animad. on Newton's theory, ii. 175, Linus ; reply 176 — optical observ. on the rainbow, ii. 222, Linus — further animadversions on Newton's theory, ii. 260 — Newton's reply to Linus, and further explan. ii. 26l, 263 particular answer to Linus's objections, ii. 276 ■ exceptions against Newton's theory, ii. 334, .... Lucas — and diaphonous bodies, queries on, iii. 600, Halley ■ on the refractions of fluids, v. 616, Hauksbee — experiments on light and colours, vi. 229, • • Desaguliers — experiment on the refrangibility of light, vi. 239, Same — different refrangibility of coloured, vi. 607, Desaguliers — colours of a secondary rainbow, vi. 624, .... Pemberton — different refrangibility of the rays, x. 390, Melville ; remarks on the same, x. 390, Short — refrangibility of the rays of, x. 530, Clairaut — to remedy the defects in object glasses arising from the different refrangibility of rays, xi. 267, Dollond — aberration of refracted light, xi. 514, .... Klingenstiern — refracted through a lens, aberrat. of, xi. 517, Maskelyne — of refracted rays reunited into a colourless pencil, xi. 718, Murdocfc — difficulties in the Newtonian theory removed, xiii. 65, 210, Horsley — refraction and velocity of the rays of, xv. 184, Wilson ; account of this discovery by Mr. Wilson, 192, . . Note — comparative intensity of light from different luminous bodies, xvii. 359, Rumford — loss of, in its passage through glass, xvii. 36'8, . . Same — on its inflection, reflection, and colours, xvii. 725, xviii. 196, Brougham — on the reflexibility of the rays of, xviii. 320, .... Prevost — a singular instance of atmosph. refrac, xviii. 337, Latham — powers of the prismatic colours to heat and illuminate, xviii. 675, Herschel — refrangibility of the invisible solar rays, xviii. 688, Same — see Optics, Refraction, Object glasses, Colours. — (for all Sir I. Newton's papers on the subject, see Newton). Light (phosphoric) from quicksiver, ix. 199, • • Trembley — articles which imbibe light, ix. 209, Beccaria — observations on phosphoric light, xv. 678, Morgan — produced by heat and attrit., xvii. 128, 215,. . Wedgwood — see Phosphorus, Electricity. Lightfoot, Rev. John, biograp. account of, xv. 630, . . Note — an account of the reed wren, ibid — description of some minute British shells, xvi. 80 Lightning, nature of, ii. 146, Mayo — compared with phosphorus, ii. 651, Slare — caused by pyrites, iii. 16, Lister — effects of, vii. 104 Wasse — magnetism communicated by it, viii. 24, 25, . . Cookson viii. 46'3, .... Bremond — cause of its angular shape, viii. 68, Logan — electrical experiments on the nature of, x. 212, Franklic — on the fusion of metallic bodies by, xi. 393, Mountaine 64 LIS INDEX. LLO Lightning, xi. 394, . Knight — case of a man burnt by it and cured, xj. 625, . . Huxham -*- method of protecting ships from, xi. 660, "Watson questions by M. Calendrini on the best means of pre- venting damage by it, xii. 127; answers by Dr. Wat- son, particularly regarding powder magazines, ibid means of securing St. Pauls from, xii. 620, Comm. it. s. appearance on a ship's conductor, xiii. 35, Winn on the means of securing the Purfleet powder magazine, xiii. 371, xiv. 354, Committee R. s. — best means of securing buildings, xiii. 374, .... Wilson — a storm of, without thunder, xiii. 539, Nicholson -— effects on a house with conductors, xiii 659, • • Henley — effects of, on bullocks, xiv. 90, Same — papers on the accident at Purfleet, xiv. 332 — effects of, on board the Atlas, xiv. 510, Cooper — effects of, at Heckingham, xv. 306, Blagden — some extraordinary effects of, xvi. 662, .... Withering — see Conductors, Electricity. — for other effects of, see Thunder and Lightning. Lily, on the farina of the red, viii. 731, Needham Limax, on the snail producing purple, xi. 225, . . Peyssonel Limbird, James, strata of a well at Boston, xvi. 183 Lime, experiments on lime-water, x. 204, Alston — lime-wat. a preservative from putrefaction, x. 358, Hume x. 551, Hales — of the sorts of, used in agriculture, xviii. 548, Tennant — for lithontnptic effects of lime-water, see Stone. Lime trees, observations on the seed of, ii. 591, Leuwenhoek Limpet fish, specimen of, xi. 313, Forbes — generic character of, ibid, Morton Linck, John Henry, commentary on cobalt, vii. 171 Lincolnshire, on the natural history of, iv. 1 17, .... Merret Lind, James, m. d., transit of Venus, 1769, observed near Edinburgh, xii. 655 — lunar eclipse, 1769, near Edinburgh, xiii. 66l — description of a portable wind-gage, xiii. 66l Lindelstolpe, bones of a foetus voided per anum, vii. 53 Lindo, Moses, a dye from a berry of South Carolina, xii. 4 Lines, see Curves, Locus. Linen cloth, machine to weave of itself, ii. 439, • • Gennes Lining, J., m. v., statical exper. on himself, viii. 683, ix. 110 — meteorological observations at Charlestown, ix. 514 — fall of rain 1738-52, at Charlestown, x. 401 — experiments with the electrical kite, x. 522 Linseed oil, spontaneous inflam, by, xvii. 449,. • Humfreys Linus, Francis, on Newton's theory of light, ii. 175 — optical observations on the rainbow, ii. 222 — further animadversions on Newton's theory, ii. 260 — decay of his dials at Liege, v. 5 1 Lion, dissection of a, i. 192 — remarks on the food of, ii. 289 Liquor, from apples and mulberries, i. 177, . . . Colepresse Liquors (Chemistry) a self moving liquor, iii. 222,. . Boyle Liquors (Medical) see Injection, Lacteals. Liquors (Natural Philosophy) occupying a decreased space when mixed, v 644, Hauksbee — see Water,, Fluids. Lisbon, effects of the earthquake of 1755, x. 656, Wolfall Lisle, Jos. Nic. de, see Delisle. Lister, Martin, biographical account of, i. 556, .... Note — journal of the bleeding of a sycamore, ibid — bleeding of sycamores and other trees, i. 558 . — circulation of sap in trees, i. 576 — on Willughby's remarks on sap, i. 579 — insect husks of the kermes kind, i. 598, 607 ; ii. 7 — a viviparous fly, i. 600 ; different sorts of spiders, 601 — of an insect feeding on henbane, i. 602 Lister, Mar., of vegetable excrescences, i. 633, 646, 64p — remarks on fossil shells, i. 645 — enquiry concerning tarantulas, i. 649 — of a musk-scented ant, i. 649 ; ichneumons, ibid — veins of plants, and their use, i. 668 ; ii. 34 — a stone cut from under the tongue, i. 716 — worms, supposed to spring from horse-hairs, i. 717 — on the agaricus piperatus, ii. 33 — passage of chyle in the lacteal veins, ii. 75, 554 — of the guts ; and of worms in them, ii. 76 — a subterraneous fungus, ii. 119 ; a mineral juice, 120 — account of trochitae and entrochi, ii. 121 — different species of snails, ii. 138 — efflorescence of crude alum, and marcasite, ii. 179 — an odd-figured iris, ii. 180 ; glossopetrae, ibid — lapides Judaici found in England, ii. 181 — attraction of resin by certain stones, ibid — flower and seed of mushrooms, ii. 183 — vitrification of antimony by cauk, ii. 183 — description of astroites, or star-stones, ii. 200 — worms voided at the mouth, ii. 226 — Roman urns, &c. near York, ii. 518 — of a monstrous animal voided by vomit, ii. 539 — on colouring the chyle in the lacteals, ii. 554 — Roman monument near North Shields, ii. 580 — case of hydrophobia, and treatment, ii. 608 — on Roman architec, a wall and tower near York, ii. 635 — colour and distribution of the chyle, ii. 637 — on the use of the caecum intestinum, iii. 1 — on salt-springs, and sea-water, iii. 10 — on earthquakes, on pyrites, iii. 17 — projection of spider's threads ; bees lodged in leaves ; viviparous flies, iii. 46 — proposal for maps of the soil, iii. 82 — rising, &c. of quicksilver in the barometer, iii. Q5 — account of the reprint, of Goedartius on insects, iii. 106* — on the freezing of* different salt-waters j on the nitre of Egypt, iii. lOf — calculous concretion on a piece of iron found in the body of a boy, iii. 121 — ornithological notes, presented to Mr. Ray, iii. 214 — answers to queries respecting shells, iii. 501 — of some transparent pebbles, iii. 543 — of shells found in the East Indies, iii. 573 — on the making and tempering of steel, iii. 570 — differences and nature of juices of plants, iv. 123 — of several plants fit for hay, iv. 1 3o — of the long worm troublesome in the East Indies, iv. 137 — dissection of the scallop, iv. 170 — venom in the tooth of a porpoise, iv. 211 — cases of hydrophobia cured, iv. 286 — on Leuwenhoek's hypothesis of generation, iv. 310 — origin of white vitriol, and figures of its crystals, iv. 427 — of powder-blue passing the lacteal veins, iv. 570 — of the quantity of blood in the body, ibid Lithotomy, see Stone Liver, nature, office, and use of the, i. 322, Malpighi — case of an abscess in, ii . 449, Tyson — human, apparently glandulous, iii. 248, Brown — imposthumation of, vii. 500, Short — cystis in, full of water, ix. K 8, Jernegan — successful treatment of hepatitis, xii. 289, Smith Lizard, scaly [manis pentadactyla] account of the, xiii. 8, Hampe — see Lacerta. Lloyd, Edward, paper of asbestos found in Wales, iii. 105 Lloyd, George, fall of rain near Manchester and Leeds, 1765-9, and 1772 to 7, xiv. 391 ; 1778-1781, xv. 193 LON INDEX. LUG 65 Lloyd, John, account of Elden Hole, Derbyshire, xiii. 137 — of an earthquake near Denbigh 1781, xv. 115 — of an earthquake in Wales 1782, xv. 353 — discovery of native gold in Ireland, xvii. 677 Lloyd, Phil., m. d., diseases of Russians, Poles, &c, iv. 420 Load-stone, a large one dug in Devonshire, i. 149, Cotton — power of, at different distances, v. 696, .... Hauksbee 6ee Magnet, &c. Loam, account of what is called Windsor loam, ix. 337, Hill Loblolly-bay [gordonia lasianthus] descrip. of, xiii. 84,Ellis Lobster, dissection of an hermaphrodite, vii. 398, Nicholls Loch Ness, history and antiquities of, iv. 398, Fraser Lock, John, biographical account of, v. 207, Note — of a man with horny excrescences, iv. 176 — register of the weather at Oates, v. 206 — water-spout in Cumberland, x. 18 — books and mss. found at Herculaneum, x. 586 — Roman inscriptions at Tunis, xii 4 Locke, Mr. — , an extraord. memory for calculation iv. 600 Locus, for three and four lines, xii. 60, Pemberton Locusts, an extraordinary swarm in Languedoc, hi. 319 in Wales, iii. 6'19, . • Floyd — in Wallachia, Moldavia, &c, in 1748, ix. 629 — description of the cicada rhombea, xii. 98, Felton septendecim, xii. 100, Collinson Lodwicke, Francis, essay for an universal alphabet, iii. 310 , — 1 — — — primer, iii. 314 Logan, J., on Godfrey's improve, of Davis's quadr., vii. 669 — impregnation of the seeds of plants, viii. 57 — cause of the angular shape of lightning, viii. 68 — apparent difference in the size of the sun and moon, near to, and at a distance from, the horizon, viii. 112 Logarithms, construction of, iv. 18, Halley — analogy of logarithmic tangents to the merid., iv. 68, Same — general method of making, v. 609, Craig — method of making, vi. 80, Long vi. 304., Taylor — construction of, on Gunter's scale, x. 338, . . Robertson — and infinite series, x. 396, Dodson — construction of, xiii. 190, Jones — problems on interpolations of, xiv. 483, Waring — theorems for computing, xiv. 6*82, Hellins — arrangement of, on graduated lines for instruments, xvi, 262, Nicholson — impiov. of Mr. Jones's computation of thelog. 10, xvii. 699 Emerson's xvii. 702 Logarithmic curve, on the quadrature of, iv. 318, .... Craig Logarithmic tangents and secants, on the method of com- puting tables of, and on their discovery, i. 69, .... Note London, magnitude compared with Paris, iii. 320, 342, Petty vii. 229, ..Davall — remarks on the population of, \iii. 257, Maitland — heat of London and Edinburgh comp., xiii. 6S5, Roebuck — the number of its inhabitants compared with the actual natives, xv. 123, Bland — see Mortality, (Bills of.) London-Bridge, of the water-works, vii. 442, ... Beighton Long, John, method of making logarithms, vi. 80 Longevity, of inhabitants of the Bermudas, i. 284, Stafford — account of Thos. Parr, i. 319, Harvey — some aged persons in North of England, iii. 48, . . Lister — account of Henry Jenkins, iv. 92, Robinson of John Bayles, v. 299, Keill — in two parishes in Shropshire, v. 357, Paxton ■ — of two sisters in Yorkshire, vi. 45, Richardson — dissection of a person aged 109, vi. 652, . . Scheuchzer — instances of, vii. 213, Degg Longfield, John, m. d., astrono. observ. at Cork, xiv. 511 Longitude, success of pendulum watches for the, i. 7, Holmes ; on the use of them, i. 343, Huygens — observations of the moon and occulted stars for, vi. 308 — observed by falling stars, vii. 207, Lynn — proposal for finding at sea, vii. 501, Halley — lunar method of discovering at sea, xi. 636, Maskelyne xi. 641, De la Lande — practice of the lunar method at sea, xii. lrJl, . . Horsley — method of measuring degrees of, xii. 291, .... Mitchell — to determine by eclipses of Jupiter's sat. xii.352,Wargentin Longitude (of places) of Moscow, iii. 421, . . Timmerman — Pekin, iv. 233, Cassini — Canton, iv. 318, Same — Cambridge in New England, v. 149, Brattle — Magellan Straits, vi. 112, Halley — of the Cape of Good Hope, vi. 41 5, Same vi. 415, Note — Buenos Ayres, vi. 549, Halley — Port Royal in Jamaica, vi. 619, Same — Carthagena in America, vi. 620, Same — New York, vii. 49, Burnet — Lisbon, vii. 141, Bradley — New York, vii. 142, Pound — of Toulon, vii. 1 44, Laval — of several places compared, vii. 335, Derham — Hudson's Bay with London, viii. 147, Bevis — difference of London and Lisbon, x. 462, Short and Paris, xi. 649, . . De la Lande Greenwich and Paris, xi. 713, .... Short — of St. John's Newfoundland, xii. 156, Winthrop — Hudson's Bay, xiii. 32, Wale* — King George's Island, xiii. 175,. .... Green and Cook — of Judda, xiii. 287, 289, Newland — difference of London and Paris, xiv. 131, . . Wargentin — of Louvain and Brussels, xiv. 401, Pigott — Cork, xiv. 511, Maskelyne — Cambridge, New England, xv. 156, Willard — York, xvi. 145, Pigott — the royal observatory, Greenwich, xvi. 236, Maskelyne — of places deduced from a solar eclipse, xvi. 529, • • Piazzi — of some places near the Severn, xvi. 709, Pigott — of Dunkirk and Paris from Greenwich, xvii. 67, Dalby — of various places in Denmark, xvii. 353 Bugge Looseness, on the use of ipecacuanha for, iv. 237, • . Sloane Lophius, (fish) description of the, xi. 717, Ferguson Lord, Rev. Thos , of worms living when cut asunder, viii.6'92 Lorimer, J., of a new dipping-needle, xiii. 593 Lotteries, on the chances of, iii. 517, Roberts Loughs, see Ireland. Lough Neagh, petrifying quality of, iii. 23, 105, Molyneux iii. 195, Smyth observations on, vi. 67, Nevill — of the petrifactions of, ix. 282, Simon Louisiana, description of, iii, 153, Henepin Lovell, Lord, meteor at Holkham, 1741, viii. 604 Lower, Rich., m. d., biograph. account of, i. 197,. . . . Note — on the respiration of a wind-broken horse, i. 197 — experiment of transfusion on a human subject, i. 203 — an undescribed blemish in a horse's eye, i. 216 Lowther, Sir Jas., foul air extracted from a coal-pit, vii. 6l2 Lowthorp, J., experiment on the refraction of air, iv. 432 Luc, John Andrew de, a new hygrometer, xiii. 469 — his rule for measuring heights by the barometer adapted to the English measure, xiii. 520, Maskelyne — depths of the mines of Hartz by the barom. xiv. ISO, 574 — essay on pyrometry and areometry, xiv. 387 — on hygrometry, xvii. 1, 111, 260 — on evaporation, xvii. 259 I 66 LYS INDEX. MAC Lucas, Anthony, on Newton's theory of light, &:c. ii. 334 Lucas, Charles, description of the Cave of Kilcorny, viii. 409 — stones in the kidney of a woman, ix 340 Lucas, R , Alicant soap and lime-water for the stone, ix. 340 Ludlam, Rev. Wm„ a new balance for thread, &c. xii. 233 — transit of Venus and solar eclipse, 176Q, Leicester, xii. 641 — occultation of £Tauri by the moon, 1770, xiii. 59 — astronomical observations at Leicester, xiii. 665 — solar eclipse June 1778, at Leicester, xiv. 46 1 — instrument for drawing and turning ovals, xiv. 700 Luffkin, T., antiq. of Arabian numerals in England, iv. 415 — application of the pneumatic engine for cupping, iv. 451 Luffkin, John, large bones near Colchester, iv. 606 Lukens, John, transit of Venus, 1769, Philadelphia, xii. 649 Lulofs, John, transit of Venus over the sun, 176l, xi. 571 — solar and lunar eclipses at Leyden, 1762, xi. 669 eclipse, 1765, at Leyden, xii. 276 Lumbago, lumbago rheumatica convulsiva, iii. 621,. . . . Pitt Lumbricus hydropicus, some account of the, iii. 445, Tyson Lumbricus latus, and teres, remarks on, ii. 591. 605, Tyson Luminousness, of the water in the Indian seas, vi.53, Bourzes Lunenburg, rich salt spring at, i. 49 Lungs, on blowing with bellows into the, i. 195,. . . - Hook — the left lobe wasted without an ulcer, i. 200, . . . Fairfax — of frogs, tortoises, dec. structure of, i. 589, .... Malpighi — of stones in the, i. 595, Kirkby — structure of, ii. 3, Templer — of animals with, but nopulm. artery, ii.69,Swammerdam — ill effect of mercury on the, iii. 436, Moulin — of a viscous excretion about the, iv. 221, Clarke — of a polypus in the, iv. 488, Bussiere — on balsamic remedies to diseased, iv. 673,. . Leuwenhoek — cure of an aposthumation, v. 37,- • Wright; 41,. . Cowper — motion of the air expired from, vi. 342, Jurin — effect of, upon blood, vii. 36l , Nicholls — case of a part coughed up, viii. 468, Watson — cure of an abscess of, viii. 620, Schlichting — case of a boy shot through the, ix. 67 , Peters — recovery from suffocation by distending them, ix. 103, Fothergill — case of an extraneous body forced into, xii. 188, Martin — case of one of the lobes wanting, xii. 199> Paitoni Lunula, on the quadrature of the, iv. 452, .... Wallis, &c. — to find the solids of the, iv. 505, Demoivre Lupi-crepitus, see Lycoperdon. Lusus naturae, see Monsters. Luxation, of the thigh-bone and reduction, xi. 482, White — see Os Femoris, &c. Lycoperdon, fornicatum, description of, ix. 93, . . Watson Lymphatic vessels, on the use of, i. 283, Bills — insertion of, into the veins, vi. 445, Hall — origin and use of, xi. 145, Akenside — of the lymphatic system in birds, xii. 556, .... Hewson lymphatics of the urethra, xii. 667, Watson Lyncei, an Italian acad., institution of, i. 52 Lyncurium of the ancients, observ. of, xi.419,. • • • Watson Lynn, George, observ. of Jupiter and Saturn, vii. 132 . — of the lumen boreale Oct. 1726, vii. 183 — observ. of the longitude by falling stars, vii. 207 — eclipses of Jupiter's satellites, viii. 58 — meteorological observations 1726 to 1739, viii. 486 Lynx, formation of the bowels of the, ii. 291 Lyons, Israel, calculations in spherical trigonometry, xiii.690 Lyon, Rev. John, a sinking of the earth in Kent, xvi. 91 Lysons, D. m. d„ of thecepphus [larus crepidatus] , xi.541 — case of Dr. Bradley, suppression of urine, xi. 663 — pins swallowed, arid discharged at the shoulder, xii. 590 Lyre, thoughts on the Greek and Roman, iv. 712, Molyneux Lyster, Thos., of a Roman Sudatory in Shropshire, v. 290 Lyttleton, Rev. Charles, biograph. account of, ix. 510. Note — description of a fossil nautilus, ibid — fossil nondescript, x. 105 M Macbride, David, if. D., reviviscence of snails after being preserved many years in a cabinet, xiii. 565 — improved method of tanning, xiv. 304 Maccausland, R., customs, of N. American Indians, xvi. 93 Macclesfield, Earl, biographical notice of, x. 33, .... Note — on the solar and lunar years, epact, and Easter, x. 33 Macdonald, J., diurnal magnet, variat. at Sumatra, xviii. 29 — diurnal magnetic variation at St. Helena, xviii. 555 Macgouan, J., meteorological observ. at Hawkhill,xiv. 390 Machel, Thomas, antiquities in Westmoreland, iii. 25 Machin, John, biographical account of, vi. 3/4, Note — curve of swiftest descent, ibid. — case of a distempered skin, vii. 543 — solution of Kepler's problem, viii. 177 Machine (chirurgical,) a machine for reducing femoral frac- tures, viii. 454, Ettrick — steel-yard swing to cure deformities, viii. 549, Sheldrake — for raising unwieldy patients, viii. 654, Le Cat — for reducing luxations of the arm, viii. 659, Same a dislocated shoulders, viii. 706, .... Freke — see Instruments, (Surgical.) Machines (mechanical,) a machine for directing a cata- dioptric telescope, vi. 646, Hadley — for measuring a ship's way, vii. 126, 338, Saumarez — for measuring the sea's depth, vii. 275, .... Desaguliers — improvements in the crane, vii. 369* Same — of Perault's axis in peritrochio, vii. 377, 380, .... Same — of the wooden-horse of the ancients, vii. 381, ... . Ward — for ventilating rooms, viii. 12, 13, 15, Desaguliers — for measuring the expansion of metals, viii. 82, . . Ellicot — for grinding spherical lenses, viii. 451, Jenkins — to blow fire by the fall of water, ix. 100, Stirling — a water-wheel for mills, ix. 182, Arderon — for sounding depths at sea, ix. 228, Cock — for measuring the expansion of metals, x. 482, Smeaton — for determining the proportion between moveables act- ing by levers, and wheel and pinion, xiv. 454, Le Cerf — see Engines, Instruments, Naxigation, Ships. Macie, J. Louis, chemical experts, on tabasheer, xvii. 101 Mackarness, J., stone voided by the anus, viii. 441 Mackenboy [tithimalus hibernicus,] medicinal effects of, iv. 303, Ashe Mackenzie, Alexander, m. d., of a woman who lived a long time without food, xiv. 121 Mackenzie, G., M. d., of the coati mondi of Brasil, vi. 653 Mackenzie, Sir G., storm, & some lakes in Scotland, ii. 210 — agricultural observations in Scotland, ii. 226" Mackenzie, Mordach, m. d., tides in Orkney, ix. 667 — plague at Constantinople, x. 239, 242, 283 ; xii. 102 — on quarantine as performed in England, x. 239 — of the earthquake at Constantinople, 1754, x. 548 — times of the appearance and disappearance of the plague at Constantinople, in the years 174S to 1761, xii. 108 Mackinlay, Robert, eruption of Vesuvius, 1760, xi. 522 — discovery, at Rome, of a statue of Venus, xi. 523 Macky, Mr., sort of venereal disease, in Edinb.1497, viii.675 Maclaurin, Colin, biographical account of, vi. 356, . . Note — construction and measure of curves, ibid. — new method of describing curves, vi. 392 MAG INDEX. MAL 67 Maclaurin, Colin, on equations with impossible roots, vii.145 • — description of curve lines, viii. 41, 43 — solar eclipse, Edinburgh, and neighbourhood, viii. 169 — of the meridional parts on a spheroid, viii. 514 — forms of the cells of honey-combs, viii. 709 Macreuse, [anas nigra] nature of the, iii. 173,. . . . Robinson — remarks on, iii. 1 74, Ray Mad-animals, cure for the bite of, iv. 232, Dampier Madden, T. m. d., poisonous quality of laurel-water, vii. 468 — dissec. of a person who swallowed crude mercury, viii. 80 — a plum-stone lodged in the rectum, viii. 81 Madder, effect of in tinging the bones, viii. 420, DuHamel Madeira, meteorological observ. at, x. 232, 488, Heberden — increase of population at, xii. 475, Same — see Earthquakes. Madness, efficacy of camphor in maniacal disorders, vii. 206 Kinnier — see Dog, Hydrophobia. Madrepora, account of the madrepora, x. 154, .... Donati Magee, William, transit of Venus, 176*1, Bengal, xi. 645 Magellan, on the longitude of the straits, vi. 113, . . Halley Magic lantern, to colour the figures of, iv. 317. Southwell Magliabecchi, Anthony, biograph. account of, iv. 218, Note — particles of silver dissolved in aquafortis, v. 368 Magnesia, chemical analysis of, xv. 244, Kirwan Magnet, of a large loadstone dug up in Devon., i. 149, Cotton — its attraction weakened by heat, i. 177, .... Colepresse — experiments with magnets, i. 166, Sellers — magnetical experiments, iv. l6l — on the magnetism of drills, iv. 332, Ballard — magnetical experts, and observs., v. 258, 259, Derham — of its power at different distances, v. 6()6,. . . . Hauksbee — experiments on the attraction of, vi. 168, Taylor — i on the power of, vi. 528, Same — on magnetic powers, vii. 105, Muschenbroek — experiments and observations with, vii. 400,. . . . Savery ■ viii. 246, 247, Desaguliers — of magnets with more than two poles, viii. 246, Eames — magnetical experiments, ix. 71, 390, Knight — varied situations of the poles of, ix. 122 Same — magnetic properties of brass, xvi. 57, 170, .... Cavallo copper and zinc, xvi. 59, . . Same 1 brass and iron filings, xvii. 148, Bennet — see Needle, Compass. Magnet, (variation of) to find the variation at sea, i. 153 — of magnetical variation* and experiments, i. 187, • • Petit «— discoverers of a decrease in the variation, i. 189, • • Note — variation near Bristol, i. 264, Sturmy — table of predictions of variations, i 283, Bond — variations at Rome, i. 434, Auzout Dantzic, i. 5 !4 ; cause, 515, .... Hevelius — calculation of variations, ii. 78, Bond — remarks on the variation, ii. 488, Sturm — table of variations, and theory of, ii. 6*24, Halley — variation at Cape Cot so, iii. 32, Heathcott at Nuremberg, 1685, iii. 244, Eimart at Siam, 1685, iii. 346 — experiments by u. s. respecting variation, iii. 384 — cause of change in variation, iii. 470, Halley — difference in surveys made at long intervals, in conse- quence of magnetic variation, iv. 180, .... Molyneux — remarks on Halley's chart of variation, iv. 655, . . Wallis — table of, in the Atlantic and Ethidpic oceans, 17 06, v. 36l — on the remarks by the Paris Royal Academy, of his chart of magnetic variations, vi. 112, Halley — observations in the Baltic, vi. 498 Sanderson — in the Pacific ocean, table of, vi. 519, Halley — on a voyage, table of, vi. 569, Cornwall Magnet (variation of) variation of the horizontal needle, 1723, vii. 27, Graham — in a voyage to Hudson's bay, vii. 136, -J-65, 617 ; viii. 591 Middleton at Vera Cruz, 1726-7, vii. 224, Harris at Wittemberg, vii. 385, Weidler — in a voyage from Java to St. Helena, vii. 552,. . Halley — observations of, in the Atlantic, vii. 604, Harris — observations in voyages to Maryland, viii. 339, Hoxton — variations of the needle to the westward, ix. 499, Graham — remarks on the variation, x. 165, Wargentin — advantage of a periodical review of the variation, x. 556, Mountaine and Dodson — observations on magnetic variations, xi. 149, • • • • Same — tables of observations from 1700 to 1756, xi. 151, Same — on the regular diurnal variation of, xi. 421, ... . Canton — observations of variation at sea, 1760-1-2, xii. 336, Ross — at Hudson's bay, xii. 684, Wales in Russia, xiii. 63, Mallet — tables of obser. in a voyage round the world, xiii. 178, Cook — instrum. for observs. used by the r. s. xiv. 54, Cavendish — diurnal vatiation at Sumatra, xviii. 29, . . . .Macdonald — cause of magnetic variation, ibid, Same — diurnal variation at St. Helena, xviii. 355, Same — see Needle. Magnet, (artificial) Mr.Seller's thediscoverer of, i. 167, Note — to communicate magnet, without a loadst., vii. 540, Marcel — magnetism communica. by lightning, viii. 24, 25, Cookson — a file rendered magnetical by lightning, viii. 463,Bremond — experiments with, ix. 393, Knight — method of making, x. 131, Canton — on giving magnetism to brass, xi. 285, Arderon — account of Knight's magnetic machine, xiv. 1 17, Fothergill — Knight's method of making, xiv. 480, Wilson — see Iron. Magnetic sand, experiments on, vii. 647, ..Muschenbroek Magnitude, on comparing magnitudes, xiv. 183, .... Glenie Mahon, Lord, see Stanhope, Earl. Mairan, M. biographical notice of, vii. 637, Note Maire, Christ., lunar eclipse, 1749> x. 4 solar eclipse, 1750, ibid Maitland William, biographical notice of, vii. 6l0, . . Note — remarks on some bills of mortality, vii. 6l0 — remarks on the population of London, viii. 257 Maize, description culture, and use of, ii. 465, . . . Winthrop — advantage of cultivating, iii. 588, Bulkley — note on the use of, ibid, Ray Malabar, of the productions of, i. 689, Baldaeus Maleverer, Mr., of coal borings, strata of earths, iv. 353 Malfalguerat, Mizael, a tumour on the thigh, viii. 410 Malholm Tarn, description of the lake, viii. 465, .... Fuller Mallet, F., transit of Venus June 176l, at Upsal, xii. 289 — parallaxes of altitude for the sphere, xii 344 Mallet, I. A., construction of water-wheels, xii. 446 — transit of Venus 1769, at Ponoi, xiii. 6l — on the lengths of pendulums, xiii. 62 — magnetic variations in Russia, xiii. 63 Malleus, see Ear. Mallow, increase of the seeds of, viii. 631, Hobson Malm, of the chalky concret. so called, viii. 729, Needham Malpigbi, Marcellus, biographical account of, i. 1 71, Note — observations on the brain and tongue, i. 171 epiploon, i. 202 — natural history and economy of the silkworm, i. 367 — on the lungs of frogs, tortoises, &c, i. 589 — a horny excrescence on the neck of an ox ; morbid appearances in the kidneys, iii. 49 — description of the uterus of a cow, iii. 53 12 68 M A R INDEX. MAR Malpighi, Mar., death and dissection, iv. 151, Lancisi Malt, way of making in Scotland, ii. 469, Moray Malvern waters, efficacy of the, i. 131, Beale — instances of the efficacy of, xi. 68, Wall Mamithsa, of the Arabian drug so called, xii. 371, Canning Mamiracun, an Arabian plant, description of, ibid, . . Same Mammoth, bones of, dug up in Siberia, viii. 155, . . Breyne N. America, xii. 476, Collinson Man, two men of extraordinary weight, ix. 2l6, Knowlton — specific gravity of living men, xi. 71, Robertson — see Po/ulation. Mancel, Arnold, artifi. magnets without a loadstone, vii. 540 Manchenille apple, some account of, i. 231, Note — description of the, i'. 295, Norwood — poisonous effects of, xi. 284, Peyssonel Manchester, see Population. Mancini, C. A., convex spherical glasses on a plane, i. 298 Manfredi, Eustachius, biograph. account of, vii. 247, Note — solar eclipse at Bononia, viii. 306, ibid — eclipses of Jupiter's satellites 1727, vii. 265 — occultation of Venus by the Moon 1727, ibid — lunar eclipse at Bologna, vii. 377 — transit of Mercury at Bologna, viii. 149 Manginot, Francis, m. d., an extraor. haemorrhage, iv. 547 Mangold, Matth, m. d., a mathematico-historic. table, ii. 320 Mango tree (Indian) account of, ill . 519 Mangostan, [garcinia mangost.] account of, vii. 631, Garcin Mangrove [rhizophora] some account of, i. 230, . . Note Manilla, particulars of the island, x. 673, Pye Manis, description of the manis pentadactyla, xiii. 8 Mann, Theod., Aug., theory of rivers and canals, with a list of authors who have treated on the subject, xiv. 593 Manna, observations on, ix. 31, Fothergill — produced from a tree in Italy, x. 52, More ; method of collecting it, 53 — descrip. of the tree [fraxinus ornus] xiii. 46, .... Cirillo Mantegar, [simia mormon] description of, v. 108, . . Tyson Manure, of sea shells, meth. of using, v. 403, Arch, of Dublin — of sea sand in Cornwall, ii. 206, Coxe ■ in Devonshire, v. 432, Bury — of fossil shells, ix. 82, Pickering Manuscripts, of some Indian, sent to Oxford, iv. 334, Lewis — catalogues of, printed at Oxford, iv. 341 — rules for judging the age of, &c, v. 227, Wanley — remarks on Greek surgical mss., v. 675, . . Schelhammer — to recover the legibility of decayed, xvi. 351, Blagden — a catalogue of oriental mss., xviii. 427, 563, .... Jones Maple, sugar from the juice of, hi. iiS vi. 458, Dudley Marriotte, Abbe, biographical notice of, i. 243, Note — discovery respecting vision, i. 243; M. Pecquet's remarks on, i. 245; Marriotte's answer, 443 — controversy with Perrault on vision, ii. 644 Maps, sculptured in wood, account of, i. 37, Evelyn — of the variations of soil, proposals for, iii. 82, . . Lister — construction and use of spherical, viii. 6l, Colson — on the best form for, xi. 215, Murdock — dissert, on the construction of, xi. 218, . . . . Mountaine Marble, a preparation for staining throughout, i. 44, Kircher — another method practised at Oxford, i. 44 — method of colouring, iv. 533 — a quarry of in Ireland, vi. 75, Nevill — on staining throughout, xi. 324, Da Costa — of a hot-spring in Tuscany depositing it, xiii. 10, Raspe Marcasite, efflorescence of, ii. 179, Lister Marcel, Arnold, to give magnetical virtue to iron without a load-stone, vii. 540 Marchetti, Sign., biographical account of, v. 310, ..Note Marchetti, anatomical observ. with Ray's remarks, ibid Marhabuts, (Mahometan priests of Africa), account of the xv. 348, Note Schotte, Marl, of the strata found in digging, vii. 155, .... Kelly — on different sorts in Staffordshire, xiii. 414, ..Withering Marmot, (Mus Alpinus) dissection of, vii. 181, Scheuchzer — from Hudson's Bay, description of, xiii. 329, . . Forster Marrow, on the nature of, iii. 463, Havers Mars, observations on the planet, i. 65, Hook — phases and rotation of, i. 80, , Same — period of rotation ascertained, i. 81, Cassini — calculation of the parallax, ii. 34, Flamsteed — occulted by the moon, at Dantzic, ii. 349, .... Hevelius Greenwich, ii. 350, Flamsteed Oxford, ibid, Halley — transit over a star in Scorpio, vi. 271 — occultation by the moon, Toulon, vii. 144, .. ..Laval ■ London, viii. 14S, Graham and Bevis Pekin, x. 2, Hallerstein — conjunction with Venus, Pekin, x 3, Same ibid, Gaubil — eclipse by the moon, London, x. 408, . . Bevis and Short — parallax of, x. 455, Delisle — figure, appearance, &c, of, xv. 531, Herschel — heliocentric longitude, &c. of, xvi. 621, Bugge Marsden,W„ extraor. drought at Sumatra, &phenom. xv. 127 — on the Mahometan Hejera, xvi. 510 — on the Hindoo chronology, xvi. 7^2 Marshal, (Earl, of England) of the diamond mines, ii. 405 Marshall, Humphrey, on the solar spots, xiii. 329 Marshall, John, religion, notions, customs, Martyn, John, biograph. account of, vii. 321, Note — obser. at the Peak, in Derbyshire, vii. 331 — account of the lead mines, Derbyshire, vii. 333 — a purging spring at Dulwich, viii. 52 J — an aurora australis, March 1739, viii. 525 — a new species of fungus, ix. 99 — aurora australis, at Chelsea, 1 749 50, x. 3 Borealis, 1750, x. 12 — on the sex of Holly, x. 486 Martyn, Geo., w. d., operation of bronchotomy, vii. 438 Maryland, animals, plants, &e. from, iv. 324, .... Petiver — topography, and nat. hist, of iv. 460, Jones Masercs, Francis, Esq., on an infinite series of decreasing quantities, xiv. 131 MAU INDEX. MEM 69 M3seres, Fr. Esq., on very slowly converging series, xiv. 451 — extension of Cardan's rule, xiv. 453, 624 — first discovery of Cardan's rule, xiv. 672 Maskelyne, Nevil, d. d., annual paral. of Sinus, xi. 501 — aberration of light refracted through a lens, xi. 517 — observations of Jupiter's satellites recommended to be made by the French astronomers, xi. 521 — transit of Venus over the sun, June 17^1, xi. 557 — on the going of a clock at St. Helena, xi. 604 — lunar method for the longitude at sea, xi. 636' — observation of the tide at St. Helena, xi. 647 — effects of refraction and parallax, xii. 152 — computation of the equation of time, xii. 163 — on the going of clocks, xii. 169 — of astronomical observations at Barbadoes, xii. 171 — of two astronomical papers, by J. Smeaton, xii. 535 — account of observations made in Pennsylvania, by Messrs. Mason and Dixon, for determining a degree of lati- tude, xii. 56'4 ; length of a degree deduced from the observations of Messrs. Mason and Dixon, xii. 573 — proportion of English to French measures, xii. 576 — transit of Venus and sol. eclipse, 176.9, Greenwich, xii. 583 — eclipses of Jupiter's 1st. satel. at Greenwich, xii. 671 — applications of Dollond's micrometer, xiii. 205 — on the use of the Hadley's quadrant,, xiii. 292 — adaptation to the English measure of De Luc's rule for ascertaining heights by the barometer, xiii. 520 — observs. of eclipses of Jupiter's satellites at Greenwich, compared with Mr.Holland's obs. in N.America, xiii. 527 — on measuring the attraction of hills, xiii. 700 — — _ mount Schihallien, xiii. 702 — eclipses of Jupiter's first satellite at Anticosti, xiii. 528 — description of the prismatic micrometer, xiv. 2.50 — longitude of Cork, xiv. 51 1 — return of the comet of 1532, l66l, predicted, xvi. 147 — latitude and longitude of Greenwich, xvi. 218 — effect of the differ, refrangibility of light on vision, xvi. 595 — observations of the comet of 1793, xvii. 294 — a star-like light on the dark part of the moon, xvii. 451 Mason, Abr., agitation of the sea at Barbadoes, 176"l,xi.6l4 — an epidemical disorder at Barbadoes, xi. 6*15 Mason, Charles, d. d., description of spelter j on melting iron with pit coal j a burning-well, ix. 305 Mason, Chas , transit of Venus over the Sun, 1761, xi. 595 — latitude of the Cape of Good Hope, xi. 596 — on the going of a clock at St. Helena, xi. 630 ; remarks on the same, xi. 631, Short — observations for determining the length of a degree of lat. made in Maryland and Pennsylvania, xii. 566 — on the going of a clock in Pennsylvania, xii. 578 — transit of Venus 1769, at Strabane, xiii. 80 Mason, Christ , explosion of a fire-ball, viii. 541 Masson, Francis, botanical journeys in Africa, xiv. 43 — account of the island of St. Miguel, xiv. 392 Mathematics, idea of improv. the science of, ii. 527, Pell — objections to Dr. Pell's idea, ii. 530, Mersenne ; Dr. Pell's reply, 532 ; Mersenne's answer 533 ; Descarte's opinion of the same, 533 Mather, Cotton, M. n., observ. in New England, vi. 85 Matlock, descrip. of the petrifactions at viii. 406, . . Gilks — a petrif. stratum formed by the waters, xiii. 510, Dobson Matrix, of a double matrix, i. 358, Vassal ; improperly so called, ibid, Note Matthews, Edw., sinking of a river in Monmouths. x. 696 Maty, Matthew, m. d., biograph. account of, x. 282, Note — his death, and body examined, xiv. 217, Hunter Maud, John, inflammability of air from a mine, viii. 77 Maud, John, oil of sassafras crystallized, viii. 243 Mauduit, Israel, an American Wasp's nest, x. 607 Maunoir, M., of Mr. Soemmering' s discovery of an orifice in the retina of the eye, xviii. 326 Maupertuis, P. Lewis de, biograph. acct. of, vii. 519, Note — figure of revolving fluids; appearance and disappearance of certain stars, &c. vii. 519 Maurice, M. de S., m. d., foetus in the ovarium, ii. 650 Mawgridge, Robt., effect of lightning on a ship, iv. 222 Maxwell, John, account of the Cape of Good Hope, v. 359 — magnet, variat. in the Atlantic and Ethiopic oceans,v.36l Mayer, And., transit of venus, 1799, atGrypswald, xii. 64S May-dew, an excretion from the bodies of aphides, i. 13, Note — experiments and observations on, i. 13, Henshaw Mayer, Christian, transit of Venus, June 176l, xii. 119 — lunar eclipse observed March 176*4, ibid — solar eclipse observed April 176*4, ibid — astronomical observations at Swetzingen, xii. 583 Mayerne, SirTheod., m. d., diseases of dogs & cure, iii.410 — poison of the viper's bite, and other poisons, iii. 653 May-fly, of the ephemera vulgata, ix. 290, .... Collinson — of Pennsylvania, see Bartram. Mayne, Zachary, a spout of water at Topsham, iv. 12 Mayow, Dr. John, biographical account of, i. 295 Mazeas, Abbe, analogy of thunder and electricity, x. 289 — on the electricity of the air, x. 434 — of the toxicodendron, and use in dyeing, x. 594 — ancient meth.- of painting in wax revived by Caylus, xi. 4 Mead, Rich., m.d., biographical account of, v. 1. ..Note — three cases of hydrophobia, v. 525 — account of Sutton's ventilators, viii. 553 Meal dust, of a fever caused by, xiii. 78, Latham Measures, standard Roman, viii. 74, Folkes — analogy betw. English weights &meas., viii. 422, Barlow — comparison of English and French, viii. 604, ..,.&. 8. — proportion of English to French, xii. 576, ..Maskelyne — see Foot, IVtights and Measures. Measurement of a base on Hounslow heath, xvi. 22, . . Roy — see Trigonometrical Survey. Mechanics, metaphysical principles of, ix. 217, .... Jurin — properties of mechanic powers, xi. 706, .... Hamilton — on mechanic impelling powers, xiv. 7^, Smeaton — proportion of the effect of moveables acting by levers, and wheel and pinion, xiv. 454, Le Cerf — see Springs, Lever, Wheels, Engines^ SfC. Medals, history of, iv. 235, Evelyn — of Pescennius Niger, observations on, x. 50, Boze Tetricus, x. 349, Same — see Coins. Medal (prize) donation by Count Rumford for improvements or discoveries in light or heat, xviii. 137 Medicinal spring, see Waters (Mineral and Medic.) , Springs. Medicine, knowledge of med. in the E. Indies, vi. 50, Papin Mediterranean, conjunction with the Red Sea, i. 15, Pettit ocean, through Languedoc, i. 418, — additions to the above account, i. 723, Froidour — rivers supplying water to the, iii. 389, Halley Megameter, a new one, xiv. 248, Boscovich Meibomius, biographical account of, i. 575, Note Melloon, Edmund, extraordinary size of, iv. 273, Musgrave Melon, on the vegetation of moldiness on, vi. 257, Bradley — vegetation of the seeds 42 years old, viii. 577, Triewald 33 years old, ix. 100, Gale Melville, T., differ, refrangibility of the rays of light, x. 390 Membrane, on the component parts of, xviii. 725, Hatchett Membrana tympani, see Ear. Memory, instance of the strength of, iii. 248, .... Wallis 76 MER INDEX. MET Memory, extraordinary, for calculations, vl. 6*00,. . . . Locke Mendip, account of the lead mines, i. 186, Glanvil — of the caves about, ii. 488, Beaumont — see Coal Mines. Mendoza, Rios Jos. de, on the chief problems in nautical astronomy, xviii. 9$ Menses, continuing to 70 years of age, vi. 55, Yonge Menstruum, to separate silver from copper, xvi. 696",. . Keir Menzies, Arch., anatomy of the sea otter, xviii. 34 Mercator, Nicholas, biographical notice of, i. 69, . . Note — problems in navigation, ibid — on Cassini's method of finding the apogees, eccentricities, and anomalies of planets, i. 424 Mercator's line, the invention of Mr. Wright, iv. 68, Halley — chart, defended from the censure of West, xi. 696, Dunn — ■■■ xi. 697, Mountaine Mercurial level, for Davis's quadrant, viii. 26'2, Leigh Mercurial gage, description of Mr. Brookes's, xv. 702, Note Mrcury (mineral) of working the Friuli mines, i. 10, Pope — found at the roots of plants, i. 173, Septali — manner of using it, in working silver mines, i. 2.93 — description of the Friuli mines, i. 407, Brown — incalescence of quicksilver with gold, ii. 267 — of its ascent in capillary tubes, vi. 432, Jurin — chemical experiments on it, vii. 619, viii. 93, Boerhaave — experiments by Braun on the congelation of, xi. 544 — experiments on the freezing of, xiv. 20, xv. 11, Hutchins — experiments on the expansion of, xv. 162, Cavallo — experiments on the freezing of, xv. 420, 428, Cavendish — history of exper. on the freezing of, xv. 431, . . Blagden — crystallization and adhesion of frozen, xv. 447, • . Same — congelation of, in England, xvi. 579, Walker — a new fulminating, xviii- 649, Howard Mercury (medicine) effect of, on a man working in the mines, i. 12 — experiments of injection into the blood, iii. 436, Moulin — injected into the jugulars of a dog, iv. 273, Pitt — as a cure for hydrophobia, exper. with, viii. 69, . . James — dissect, of a body dead by swallowing it, viii. 80, Madden — ill effects of taking crude, viii. 158, Cantwell Mercury (Barometer) cause of its suspension at the top of a tube, ii. 1, Huygens; otherwise accounted for, 3, . . Note — cause of its suspension, ii. 44, Wallis — height of, in the barometer, at different elevations, iii. 300, Halley — exper. on the mercurial phosphorus, v. 254, Hauksbee — see Barometer. Mercury (Planet) transit over the sun, 1690, iii. 435, Wurtzelbaur — conjunctions of with the sun, iii. 448, Halley — transit of, determining its orbit, vii. 70 — transit, 1736, London, viii. 148, Graham ■ Bonogna, viii. 149, Manfredi Wittemberg, ibid, Weidler ■ London, viii 725, Bevis — occulted by Venus, viii. 251, Same — transit at Greenwich, 1743, viii. 6l3, Catlyn New England, 1740, viii. 713, Winthrop London, 1743, viii. 714, Graham — — — viii. 725, Bevis — observations of, ix. 41, Same — transit at Giesen, 1743, ix. 307 Gersten . London, 1753, x. 370, Short Antigua, 1753, x. 414, Shervington — observations on a transit, x. 426, Short — transit, 1743, observed at Naples, xii. 554, . . Zannoni ■ ' — — Tarentum, ibid, Same Mercury (Planet) trans. 1743, NewEng., xii. 69 I, Winthrop I/69, in Pennsylvania, xiii. 83, Smith, &c. N.England, xiii. 93,Winthrop 1782, Cook's Town, xv. 456, Hamilton Paris, xv. 553, Wallot xv. 652, Zach — 1786, Louvain, xvi. 135,. . N. Pigott ibid, E. Pigott at Dresden, xvi. 182,. . . . Koghler Petersburg, xvi. 183, Rumovski — right ascension and declination of, xvi. 292, . . Smeaton Mere Diss, a metallic incrustation on substances immersed in the waters of, xviii. 421 Wiseman — analysis of the water of, xviii. 423, Hatchett Meridian, measure of the earth's meridian, ii. 193,. . Picard — choice of a place for a first meridian, ii. 236" — of any place, an instrument for finding, v. 129, Derham — of Lisbon, London, and Paris, vii. 5b, Carbone — measurement of, at Vienna, xii. 497, Liesganig — method of determining the difference of meridians, xvi. 146, Pigott — the observatory of Geneva a proper place for measuring an arc of, xvii. 34, Pictet Meridian Line, on a supposed alteration of, iv. 414, Wallis — a new way of drawing, iv. 549, 56"8, Gray — division of the nautical, vi. 184, Perks Merret, Chr., on reuniting the separated bark of trees, i. 160 — to prevent cherries from withering against a hot wall, ibid — observations on the American aloe, i. l6l — account of the Cornish tin mines, ii. 424 — art of refining gold and silver, ii. 453 — remarks on the natural history of Lincolnshire, iv. 117 Mersenne, Marin, biographical account of, ii. 530, . . Note — on Dr. Pell's idea of improv. mathematics, ibid, and 533 Mertans, C. de, m. d., on treatment for the scurvy, xiv. 401 Mesaporiti, Anthony, of a general hemorrhage, v. 248 — case of adhesion of the intestines, v. 250 Mesentery, unusual rupture of, ii. 199, • • • • Swammerdam Messier, Charles, course of the comet of 1764, xii. 116 — return of the comet of 1682, xii. 263 — solar eelipse, 1765, at Colombes, xii. 274; 1766, xii. 347 — observations at Paris of two comets, 1766, xii. 286 — auroras boreales observed at Paris, 1768, xii. 611 — transit of Venus observed at Paris, 1769, xii. 664 — various astronomical observaiions at Paris, xii. 6*82 — course of the comet of 1771, xiii. 104 — observation of a belt on Saturn's disc. xiv. 108 Metal (in general) an instrument for assaying, ii. 214, Boyle — exper. of fusing it with a burning glass, v. 501, Geoffroy — specific gravity of various rnetals, v. 698, . . Hauksbee — for expansion of, see Expansion. Metal (Chemistry) the colours of metallic particles dependent on the specific gravity of each metal, xii. l6S, Delaval — solution of metals in the mineral acids, xv. 3-7, Kirwan — affinity of mineral acids to metals, xv. 336, .... Same — dissolution of metals in acids, xvi. 694 Keir — process for separating silver from copper, xvi. 69(\ Same — cause of the increased weight of, on calcination, xvii. 245, Fordyce — see particular Metals in their places. Meteor, an uncommon one in 1676, ii. 389, Wallis — observed at Leeds, May 17 10, v. 643, Thoresby — some remarkable meteors, and their cause, vi. 99, Halley — extraordinary lights, March 17 16, vi. 213, 226, . . Same — a fiery meteor in Jamaica, vi. 368, Barham — seen all over England, March 1719, vi. 406, Halley — seen at Cambridge, March 1715, vi. 477, Cote* MET INDEX. MET 71 Meteor, of an explosion in the air, vii. 6*14-, Lewis seen in the day time, Dec. 1733, viii. 403, .... Crocker seen at Philadelphia, 1737, viii. 409, Breintnall — account of several, viii. 4,69, Short — a fire-ball, Dec. 1 741, viii. 540, Lord Beauchamp — of the same in Sussex, ibid Fuller in Kent, viii. 541, 560, Gostling — — Sussex, ibid Mason . Isle of Wight, viii. 550, Cooke London, viii. 55.9, Gordon . at Peckham, viii. 583, Milner — Aug. 1741, at Holkham, viii. 6*04, Lord Lovell — May 1741, London, ix. 46*, Craddock — July 1745, iv. 168, Costard — Dec. 1742, at Westminster, ibid, Mortimer — resembling a water-spout, ix. 6"t)8, Barker — of a fire-ball at sea, x. 19, Chalmers seen in the air, July 1750, x. 124, . . Smith , x. 126, . . Baker . Feb. 1754, x. 531, ..Hirst — Nov. 1758, observed in various parts, xi. 377, . . Pringle — remarks on the different accounts of the meteor seen Nov. 1 758, xi. 388, Same — seen Oct. 1759, in Berkshire, xi. 394, Forster . at Bath, ibid, '. . Colebrooke - — — in Essex, ibid, Dutton May 1760, New England, xi. 515, . . Winthrop Sept. 176*0, at Oxford, xi. 535, Swinton ■ Dec. 1761, at the Hague, xi. 677, Gabry Oct. 1763. xii. 39, Dunn — observ. of several, in North America, xii. 123, Winthrop — a remarkable one, at Oxford, 1764, xii. 163, . . Swinton 1766, xii. 401, .. . .Same . 176'9, xiii. 88 Same — a fiery meteor observed atTweedmoutb, 1772, xiii. 415, Brydone — meteoi ic appearance in a mist, xiv. 639, Cockin — observed Aug. 18, 1783, at Windsor, xv. 477, . . Cavallo Depiford, xv. 479, • • Aubert — York, xv. 480, .... Cooper , , . Mullinger, xv. 481, Edgeworth — of some meteors and how caused, xv. 520, .... Blagden — of Aug. 1783, observed near York, xv. 620, .... Pigott — see Light (Meteoric). Meteorological observations, a method of registering them, iii. 139, Plott — fall of rain at Gresham College, one year, iv. 121 . in 1698, iv. 349, . , Derham 1697-8, iv. 350, Townley — comparative rain at different places, v. 100, . . Derham — account of the great frost, 1/ 08-9, v- 583, Same — fall of rain for 18 years at Upminster, vi. 97, . .-•» Same ■ ■ 1722-3 in Northumberl., vi. 658, Horsley — observations at sea, recommended, vii. 224, Greenwood — account of the great frost 1730-1, vii. 448, .... Derham — observations for 1725 to 1730 at Padua, vii. 509, Poleni — remarks on the observations communicated to the r. s., vii. 660, 666, 676, Derham — diaries from various places, for 1729-30, viii. l6"3, Hadley for 1731—1736, at Padua, viii. 196, Poleni 1726 — 1739, viii. 486 — unusual warmth of the air, Jan. 1742, viii. 548, . . Miles — observ. for 1731 — 1735, viii. 617, Hadley — plan for a meteorol. diary, ix. 34, Pickering — observ. in Charlestown, South Carolina, ix. 514, Lining — a very cold and a very hot day in June and July, 1749, ix. 686, Miles Meteorological observations, excessive heat, July 1750, x. 94, Arderon — observ. with fall of rain at Madeira, 1747-50, x. 232, 488, Heberden — fall of rain at Leyden, 1751, x. 233, Van Hazen Charlestown, 1738-52, x. 400, . ..Lining — observations on the cold of 1754, x. 454, .... Arderon x. 456, Miles — excessive cold Feb. 1755, x. 066, Same — fall of rain at Antigua, 1751-4, x. 628, Byam — heat of the air, July 1757, Plymouth and London, xi. 176, 204, Huxham — extreme cold at Petersburg, Dec. 1759, xi. 480, Himsel ' xi. 544,. . Braun — fall of rain at Norwich, 1749, 1762, xi. 678, . . Arderon — mildness of the winter of 1762, in Cornwall, and fall of rain, xi. 684, Borlase — extreme cold at Berlin, Dec. 1762, xi. 694, Pallas — fall of rain for 3 months in Cornwall, xii. 99, . . Borlase — weather at Mount's Bay, Cornwall, compared with it at some other places, xii. 1 00, Borlase — degree of cold in Bedfordsh. Nov., 1763, x. 114, Howard — state of the thermom. at Quebec, 1765-6, xii. 356, Rose — extreme cold at Derby, Jan., 1767, xii. 444, Whitehurst — account of the great frost, Feb., 1767, xii. 474, Watson — fall of rain at Plymouth, 1766, xii. 475, Same ■ — Bridgwater, Carlisle, and Ludgvan, 176*7, xii. 516 — state of the thermom. at Warsaw, 17<>7, xii. 531, Wolfe — _— . Stockholm, 17l>7, xii. 535, Wargentin — heat of the summer of 1768, at Rome, xii. 579* . . Byres — of the therm, in winter at Hudson's Bay, xiii. 32, Wales — rain at Bridgw. and Mount's Bay, 1769, xiii. 46, Borlase - Mount's Bay, 1770, xiii. 126; 1771, 325, Same — journal at Lyndon in Rutland, &c, for several years, xiii. 131 j 1771,277; 1773,530; 1774,631; 1775, xiv. 48; 1776,178; 1777,389; 1778,592; 1779,511; 1780, xv. 118; 1781,277; 1782,396; 1783, 543 ; 1784, xvi. 30; 1785,95; 1786, 306; 1787, 507; 1788, 56*3; 1789, xvii. 28; 1790,74; 1791,242; 1792,335; 1793,392; 1794,613; 1795, xviii. 64; 1796, xviii. 300 ; 1797, 442; 1798, 580 Barker — remarkable cold at Caen, 1767, 1768, xiii. 146, . . Pigott Glasgow, Jan., 1768, xiii. l6l, Wilson — Francker, Jan., 1767-8, & 1770, xiii. 386, Van Swinden — journal kept by the Royal Society for 1774, xiii. 6l5 j 1775, xiv. 43; 1776, 179; 1777, 391 ; 1778, 521 ; 1779, 682 ; 1780, xv. 87= 1781, 277 J 1788, xvi. 556 j 1789, 652; 1790, xvii. 38 ; 17.91, 192; 1792, 306; 1793, 389 ; 1794, 535 ; 1795, 752 ; 1796, xviii. 138 ; 1797,315; 1798,485; 1799,666, — plan for keeping those of the r. s., xiii. 6l6, . . Horsley — view of the weather from the journals of the r. s., xiii. 617 ; xiv. 44, Same — journal kept at Bristol, for 1 774, xiii. 629; 1775, xiv. 47; 1776,179; 1777,390; 1778,593, Farr — effects of the frost, Jan. 1776, xiv. 1 16, Fothergill — diary kept at Fort St. George, xiv. 322, 681, Roxburgh — observations at York, 1774-5, xiv. 322, White Montreal, xiv. 389, 681, Barr Hawkhill, 1773 6, xiv. 390, M'Gowan — fall of rain near Manchester, 1765-9, and Leeds, 1772-7, xiv. 391 ; 1778-81, xv. 193, Lloyd — observations at Labrador, xiv. 597 ; xv. 87, . . La Trobe — degree of cold at Glasgow, Jan., 1780, xiv. 704, Wilson — journal at Senegal, xiv. 711, Schotte — observations in Somersetshire, 1782, xv. 477,. • . • Atkins — a remarkable frost, June, 1783, xv. 6u4, ...... Cullura 72 MIC INDEX. MIL Meteorological observations, phenomena in Scotland, xvi. 186, Brydone — mean heat of every month for 10 years in London, xvi. 384 Heberden — see Weather, Rain, Frost, &c. Mexico, minerals of ; a sort of gold leaves in a mine, L 293 — the lake of, composed of salt and fresh water, ii. 357 Mice, of sable mice (mus lemmus) from Lapland, iv. 36l Rycaut several species of, from Hudson's Bay, xiii. 330, Forster Michell, Rev. John, observ. of the comet of 176*0, xi. 4-28 — on the cause of earthquakes, xi. 448 — of Hadley's quadrant for surveying and pilotage, xii. 197 — method of measuring degrees of longitude, xii. 291 — of the paral. and magnitude of the fixed stars, xii. 423 — cause of the twinkling of the stars, xii. 438 — on the distance and magnitude of the stars, xv. 465 Michellotti, P. A. m. d., distemper of cattle in Italy vi. 481 — vomiting of blood, cured by cold drinks, vii. 485 Michon, Peter, Joseph, (see Bourdelot) Micrographia, by Hook, some account of the, i. 13 Micrometer, account of Mr. Gascoigne's, i. l6'l ; 195, Hook ; x. 369, Bevis — applied to the microscope, ix. 94, Hollman — on an improved plan, x. 359, Savery — on a new plan, x. 36*4, 46'2, Dollond — testimony of the efficacy of Mr. Dollond's, x. 409 various applications of Dollond's, xiii. 205, . . Makelyne — directions for using the common, xiii. 277, Bradley — of a new micrometer, xiv. 248, Boscovich — descrip. of the prismatic microm. xiv. 250, . . Maskelyne — two new micrometers, xiv. 557, Ramsden — for the angles of position, xv. 1 55, Herschel — descrip. and use of a lamp-microm., xv. 229, Herschel — for small angles with the telescope, xvii. 75, . . Cavallo Microscope, a new one, by Divini, i. 301 — Butterfield's method of making, ii. 445 — of a drop of water, iv. 97, 120, 166, Gray — remarks on microsc. observs., iv. 602,. . . . Leuwenhoek — description of his pocket microscopes, iv. 709, . . Wilson — observations made with Wilson's, v. 29, Sir C. H. — manner of making, v. 552, Adams — description of Mr. Leuwenhoek's, presented to 11. s., vi. 678, Folkes — of a catadioptric microscope, viii. 73, Barker — description of Mr. Leuwenhoek's, viii, 443, .... Baker 1 Mr. Folkes's, viii. 445, Same — account of Torre's, for the minutest objects, xii. 245 Stiles — descrip. of Torre's glasses presented to the r. s., xii. 287 Baker Microscopic observations, ii. 66, 95, 128, 149, 1^1, lfjfj, 222, 312, 374, 383, 400, 438, 460, 473, 507, 520, 536, 543, 580, 619, 6*64; iii. 36, 43, 91, 122, 146, 186, 199, 481, 503, 525, 537, 56l, 589, 660; iv. 94, 223, 268, 419, 46*4, 477, 491, 509, 514, 541, 557, 570, 587, 66*8; v. 6, 52, 6l, 87, 94, 140, 155, 157, 16*2, 169, 188, 197, 204. 266, 281, 315, 366, 372, 374, 402, 424, 426, 449, 46l, 481, 519, 530, 537, 542, 549, 640, 660, 672, 699, 703; vi. 42, 82, 484, 502, 504, 523, 541, 570, 583, 593*, 594, 6*05, Leuwenhoek — on animalcula in water, iv. 89, Harris iv. 97, Gray — various observations with Wilson's micros., 529 Sir C. H. — farina of hollyhock and passion-flower, ix. 230, Badcock Microscopic cbserv., of animalc. in infusions, x. 698, Wright — on globules of human blood, xii. 245, Stiles — on the sexes of plants, xii. 248, Same — impregnation of vegetables, xii. 249, Same Middleton, Christ., magnetic variation in a voyage to Hud- son's Bay, 1721 to 1725, vii. 136, 46.3, 617, viii. 76 — lunar eclipse at Hudson's Bay, viii. 147 — the needle affected by cold, viii. 224 — a new azimuth compass, viii. 251 — quantity of salt in frozen sea-water, viii. 514 — effects of cold ; and of the magnetic variation, at Hud- son's Bay, viii. 591 Miguel, Saint, account of the island of, xiv. 392, . . Massou Milbourne, Wm., remarkable decrease of a river, xi. 678 Miles, Rev. H. circulation of blood in a newt's tail, viii. 501 — description of the seed of fern, viii 505 — extraordinary warmth of the air, Jan. 1742, viii. 548 — Parhelia observed in Kent, viii. 555 — on the mouth of eels in vinegar ; of a supposed aquatic animal, viii. 674 — on firing of phosphorus by electricity, ix. 107 — luminous emanations from living bodies, ix. 136- — improvements in cyder and perry, ix. l65 — electricity of sealing wax and brimstone, ix. 191 — electrical experiments, ix. 198, 232 — nature of electric fire, ix. 207 — electricity of water, ix. 213 — of Mr. Gould's account of English ants, ix. 998 — variat. of thermometer within doors and without, ix. 372 — effects of a storm of thunder, &c. in June 1748, ix. 528 — essay on quantity, ix. 559 — on thermometers and the weather, ix. 6l6 — a cold, and very hot day in June and July 1749, ix. 686 — agreement of thermom. at London and Tooting, ibid — on the green mould on fire-wood, x. 8 — observations on minute seeds of plants, ibid — aurora borealis January 1751, x. 12 — heat of the weather at Tooting, x. 94 — severe cold of the winter of 1754, x. 456 February 8, 1755, x. 566 Milford, Matthew, of a worm voided with urine, ii. 411 Milk, women of advanced age giving suck, ii. 141 — of a woman of 68 who gave suck, viii. 327, .... Stack — of a wether giving suck to a lamb, ix. 557, Doddridge — to cure by ventilation the bad taste arising from the im- proper food of cows, x. 642, I lales Miller, Cbas., experiments in the culture of wheat, xii. 555 — account of the island of Sumatra, xiv. 315 Miller, Philip, biographical account of, vii. 250, .... Note — method of raising exotics in England, ibid — experts, of the flowering of bulbous roots in water, vii. 467 — on the toxicodendron, and use as a dye, x. 596, xi. 177 Milles, Jeremiah, d. d , biograph. notice of, xi 438, Note — account of the Carlsbad waters, xi. 6*8 — particulars respecting the Bovey coal, ibid, and xi. 439 — further experiments on the Bovey coal, xi. 517 — meteorological observs. in Cornwall, &c. 176S, xii. 620 Mills, a water-wheel for, ix. 182, Arderon — powers of water and wind on, xi. 338, Smeaton — proportion of wind requisite for, xiv. 198, .... Stedman — of mills for the sugar-cane, xiv. 683, Cazaud Mills, Henry, agitation of the waters at Rotherhithe, x. 650 Mills, Abraham, strata and volcanic appearances in the North of Ireland, and in the Western isles, xvi. 6*39 — native gold discovered in Ireland, xvii. 679 Milner,, John, solar eclipse 1733, in Somersetshire, vii. 614 — lunar eclipse 1736, in Somersetshire, viii. 118 MOL INDEX. MON Milner, J., on burying of cows dead of distemper, ix. 255 Milner, Rev. Isaac, communication of motion by impact and gravity, xiv. 368 — on the limits of equations, and number of affirmative and negative roots, xiv. 382 — precession of the equinoxes,xiv. 576 — production of nitrous acid and air, xvi. 606 Milner, Thos., M.r»., meteor at Peckham Dec. 1741, viii 583 Milner, Wm., of a boy's feet turned inwards when born, cured by sitting cross-legged, ix. 695 Milnes, Wm., effects, above and under ground, of the earth- quake of 1795, in Derbyshire, xviii. 34 Milward,Edwd., m.d., antidote to W.Indian poison, viii. 54*2 Mines, machine for introducing fresh air into, i. 27, Moray — inquiries concerning, i. 123, Boyle — particulars respecting wind and water in, i. 10*8 — account of the tin mines of Cornwall and Devon, i. 563 ; method of discovering mines, ibid — of a milky mineral juice, ii. 1 20, Lister — on the mines of Spain and Germany, ii. 340, . . Bowles — methods of draining, iv. 155, Papin — engine for extracting foul air from, vii. 208, Desaguliers — observ. on a natural history of, vii. 224, 248, . . Nicholls — barom. meas. of the Hartz mines, xiv. 180, 574, De Luc — see particular mines under Gold, Silver, Copper, Tin, Diamond, Mercury, Coal, Salt, fyc. — see Damps. Minerals, on extracting sulphur and vitriol from the Liege mineral, i. 17 — account of the minerals of Mexico, and of gold leaves found in a mine, i. 293 — of the min. of Transylvania and Hungary, i. 436, Brown • — catalogue of minerals from Sweden, vi. 49, .... Petiver — experiments on the nature of some mineral substances, xiv. 120, 477, Woulfe — see Asbestos, Calamine, Cornelian, Corundum, Diamond, Emery, Liege mineral, Marcasite, Marl, Natron, Nitre, Rowky-rag, Ruby, Stalactites, Strontitcs, TaL , Terra tripolitana, Topaz, Tourmalin, Turquoise, IVadd. — see Metals, Earths, Stones, Salts. Mineral waters, see Waters (Mineral und Medicinal). Minorca, account of the island of, xiv. 68, Small Myriozoon, see Coral. Mirror (burning), see Burning-glass. Misleto, on the propagation of, vii. 176, Barrel — difference of sex in, vii. 271, Same Mitchell, John, m. d., on the causes of the different colours of people in different climates, ix. 50 — preparation and uses of potash, ix. 572 — on the force of electrical cohesion, xi. 418 Mitchell, Sir A., a shower of black dust in Zetland, xi. 138 Mites, on the production of, iv. 95, v. 660,. . . . Leuwenhoek Mithras, a bas-relief of, found at York, ix. 6S7. . . Stukely Mixture, effects of effervescent mixtures, xi. 66, Mounsey — for freezing mixtures, see Cold. Mocha, observations on a journey to, xiii. 287, . . Newland Mock suns, see Parhelia. Moehring, P. H. G., descriptions of some plants, viii. 358 Mohr, JohnM., transit of Venus, 1769, atBatavia, xiii. 181 Mercury, ibid Moisture, absorption by differ, substances, xvi. 260, Rumford — devaporation of aerial moisture, xvi. 376, Darwin Moivre, Abraham de, see Demoivre. Mole, account of a species from N. America, xiii. 148, Banington Molloy, Mr., of the earthquake at Lisbon, 1761, xi. 541 Molasses, a sort made from apples, vi. 6l8, Dudley Molucca island, of burning mountains at, iv. 163, Witsen Molybdcena, analysis of the Carynthian molybdate of lead, xviii. 4, Hatchett — experiments on molybdic acid, xviii. 21 Molyneux, William, biographical account of, iii. 295, Note — petrifying quality of Lough Neagh, iii. 23, 105 — remarks on the Connought worm, (sphinx elpenor,) iii. 120 — a new hygroscope, iii. 171 — circulation of blood in the lacerta aquatica, iii. 238 — remark on the trade- winds, iii. 239 — cause of swimming, in a lighter menstruum, of a heavier body which it dissolved, iii. 294 — why four convex-glasses show objects erect, iii. 329 — course of the tides at Dublin, iii. 333 — description of sciotericum telescopicum, iii. 336 — lunar eclipse at Dublin, 1686, iii. 342 — cause of the apparent greater magnitude of the sun and moon near and above the horizon, iii. 365 — difference in surveys at long intervals owing to the mag- netic variation, iv. 180 — of a moving bog near Limerick, iv. 206 Molyneux, T., m.d., large human os frontis. iii. 121 ; iv. 471 — observations on epidemic distempers, iii. 634 — of the giant's causeway in Ireland, iii. 657 > iv. 28 1 — the scolopendra marina (aphrodita aculeata) iv. 132, 368 — of immense horns found in Ireland, iv. 156 — swarms of cockchafers in Ireland, iv. 2l6 — to extract the stone from the bladder of a female, iv. 227 — an account of giants, iv. 471 — thoughts on the ancient lyre, iv. 7 1 2 — on some large teeth found in Ireland, vi. 200 Molyneux, Samuel, biographical account of, iii. 295, Note — effects of a storm of thunder, &c. in Ireland, v. 395 Mombazza, Pietra Di, see Rhinoceros Bezoar. Momentum, definition of the term, as contradistinguished from mechanical power, xiv. 84, Note Monarty, Mich., irregularity of tides in the Thames, x. 693 Monceau, Du Hamel, Du, see Dumonceau. Money, value of ancient Greek & Roman, xiii. 193, Raper — table of the mean depreciation of, since the conquest, xviii. 309, Shuckburgh — see Coins. Monkey, anatomy of the, iii. 392 — of the small striated [simia iacchus,] x. 170, . . Parsons — of a species without tails, xii. 608, De Visme Monks-hood, [aconitum napellus,] poisonous effects of, vii. 642, . Bacon Monmort, Remund de, on infinite series, vi. 308 Monnier, — Le, m.d., communication of electric, ix. 275 Monnier, P. C. le, biographical account of, ix. 591, . . Note — solar eclipse, 1748, at Edinburgh, ix. 591 Monochord, see Music. Monoculus polyphemus, on the eye of, xv. 323, Andre Monoculus apus, account of, viii. l6l, Klein ; 163, Brown — see Bivalve Insects. Monro, Donald, m.d., experiments showing the varieties in vegetable acids, xii. 479 — efficacy of quassia in fevers, xii. 515 — of the native natron found in Tripoli, xiii. 216 — of the Castel Leod waters in Rosshire, xiii. 271 — of the salt purging waters at Pitkeathly, xiii. 272 Monro, John, m. p., of the catacombs of Rome, iv. 5! I Monsoons, &c. accounted for, iii. 210, Garden — and trade-winds, cause of, iii. 320, Halley viii. 19, Hadley Monsters, a colt's head with eyes united, i. 29, Boyle — two monstrous births at Paris, i. 167 in Devon, ibid, Colpresse — — ■ — — — at Venice, i. 435, Grandi K 74 MOO INDEX. MOO Monsters, a monstrous birth, with anatomical observations, i. 531, Durston — uncommon foetus, ii. 1 \6, Denys — conjoined twins, ii. 493 — a monstrous pig, ii. 6l7 — of a monstrous child, iii. 48, Krate — a double cat, iii. 207 Mullen child of 6 years old with a woman's face, iv. 31, Sampson child born with a wound in the breast, iv. 102, Cyprianus — infant with a double head, iv. 207, Gaillard — bones deficient in the head, iv. 208, Same — calf with two heads, iv. 240, Southwell — two monstrous pigs, and a double turkey, iv.458, Floyer — child with the intestines, &c. in the thorax, iv. 630, Holt — of an extraordinary double child, v. 51 , Ellis — case of conjoined twins, v. 333, Taylor — of a monstrous calf, v. 365, Adams — of a double child, v. 486, Derham — head of a monstrous calf, v. 668, Craig — a mons'rous double birth, vi. 66l, Fevry — a child with the bowels hanging out, vii. 529, Amyand — a monstrous boy, vi ii. 325, Cantwell — various instances ; on the cause of, viii. 385, . . Superville a monster whose mother was under sentence of trans- portation, viii. 401, Sheldrake a foetus resembling a hooded monkey, viii. 503, Gregory remarkable formation of a child, viii. 589, • . Warrick — infant with a pendu. tumour on the back, viii. 6*22, Baster — child of a monstrous size, viii. 727, Geoffroy — a gigantic child, ix. 95, Almon and Dawkes — child born with its bones displaced, ix. 351, Davis — double foetuses of calves, ix. 555, Watson — a monstrous lamb, ix. 557, Doddridge — two conjoined female children, ix. 568, Parsons — a foetus without distinction of sex, ix. 57, Baster — account of a double child, x. 233, Percival — a sheep with a horn grown from the throat, x.601, Parsons — of a double female, xi. 142, Torkos — — — xi. 144, Burnet — other corroborative accounts, xi. 144, 145 — monstrous human foetus, xii. 362 Le Cat — cause of some monstrous foetuses, xii. 369, Same — an extraordinary acephalous birth, xiii. 654, . . Cooper — - of a singular monstrous produc. xv. 120, Note, . . Bland — description of a monstrous birth, xv. 180, .... Torlese double boy, xvi. 56l, Reichel — — — — double-headed child, xvi. 663, xviii. 443, Home — remarks on an extraordinary production of human ge- neration, xvii. 312, Clarke — unusual formation of the heart, xviii. 332, .... Wilson — dissection of an hermaphrodite dog, xviii. 485, . . Home Montagu, Edw. Wortley, bio^raph. acct. of, xii. 278, Note — journey from Cairo to Sinai, ibid — on the real date of Pompey's pillar, xii. 472 Montesquieu, J. B. S. de, biograph. notice of, ix. 12, Note — regularly shaped stones found at Bagneres, ix. 13 Monument, a remark, sepulchral, in Derbys. xi. 633, Evatt Moon, changes in the moon and earth to be seen by their respective inhabitants, i. 41 — and sun, to rind the dist. from the earth, i. 53, Oldenburg — method of finding the parallax of, i. 138 — remarkable halos about the, i. 145, . . Earl of Sandwich — cause of the secondary light of the moon, i. 314, Tacquet — Halley's tables comp. with Horrox's, v. 549, Cressener — observations on the spot Plato in, vii. 166, . . Bianchini — appt. size of the horizontal, viii. 105, 106, Desaguliers — same subject, viii. 112, Logan — remarks on the atmosphere of, viii. 371, .... ,, Fouchy Moon, motion of the, ix. 318, Dunthorne — lunar circle and 2 paraselenes, ix. 567, Grischow — acceleration of the, ix, 669, Dunthorne — mean motion of the apogee, x. 138, Murdock — extraordinary appearance in, 1751, x. 175, Short — motion of the apogee, x. 203, Euler — observations of the parallax recommended by Dr. Mas- kelyne to be made at St. Helena, xi. 519, De la Caille — on the apparent size of, near the horizon, xi. 6ll, Dunn — reasons for a lunar atmosphere, xi. 644, Same — method of determining its distance, xii. 87, . . Murdock — real distance from a star, by computation of the effects of refraction and parallax, xii. 152, Maskelyne — to compute its parall. and eclipses, xii. 181, Pemberton — observations of the lunar mountains, xiv. 717, Herschel — discovery of three lunar volcanoes, xvi. 255 ... Same — remarks on the lunar atmosphere, xvii. 232, . . Schroeter — of a stark-like light, on its dark part, xvii. 450, Wilkins — observ. on the same star-like light, xvii 451, Maskelyne Moon, (occupations, transits, conjunctions, &c.) method of observing eclipses of, i. 145, Rooke — eclipse of 1671, at London, Ecton, Paris, i. 639 i. 648,. . Hook — observations at the appulses of, i. 649, ii. 118, Flamsteed — total eclipse, 1761, i. 658, Hevelius — transit of, over Jupiter, i. 659 — eclipse of 1761, observed at Hamburgh, i. 659 — ^— — — January, 1675, at London and Derby, ii. 187 Paris, ii. 187, 193 Dantzic, ii. 205 — total eclipse, June, 1675, London, ii. 221, 224 — — — ^— — — Paris, ibid, ibid — eclipse, December, 1675, ii. 259, Flamsteed ii. 280, Cassini — transit over Jupiter, February, 1676, ii. 281, Flamsteed — eclipse, December, 1675, at Dantzic, ii. 288 Paris, Strasburg, London, ii. 299 October, 1678, at Paris, ii. 444, Cassini August, 1681, at Paris, ii. 510 at Greenwich, ibid, . . Flamsteed ' Dantzic, ii. 539, • • • • Hevelius ... St. Lawrence, ii. 557, Heathcot — 1682, Greenwich, ii. 587, . . Flamsteed — Paris and Copenhagen, ii. 605 — — — — — — Dantzic, ii. 605 —— 1684, Greenwich, iii. 69, . . Flamsteed — — — l685, Dantzic, iii. 245, .. ..Hevelius Nuremburg, iii. 318, Eimmart, &c. Lisbon, iii. 336, Jacobs 1686, Dublin, iii. 342, .... Molyneux 1685, Moscow, iii. 421 1697, Chester, iv. 222, Halley ■ Rotterdam, iv. 228,. . . . Cassini — — — — — 1703, London, v. 134, Hodgson ■" eclipses observed in NewEngland, v. 148, Brattle Apr., 1707, Zurich, v. 350, James & Scheuchzer 1 707, at New England, v. 379, Brattle 1708, Upminster, v. 48£, Derham 1710, Streatham, v. 548, Cressener 1712, Upminster, v. 700, Derham November, 1713. Rome, vi. 92, Bianchini Obtober, 1715, Wanstead, vi. 212, Pound August, 1718, Wanstead, vi. 373, Same — eclipse, June, 1722, Jamaica, vi. 619, Halley September 8, 1718, Italy, vii. 21 November, 1724, Lisbon, vii. 55, .... Carbone ■ October, 1725, Bristol, vii. 129, .... Burroughs October, 1726, Padua, vii. 162, Poleni MOO INDEX. MOR 75 Moon, eclipse, October, 1724, Rome, vii. 165,. . Bianchini (occultations, transits, and conjunctions, &c.) 1725, Albano, vii. 165, Bianchini - 1724, in Persia, vii. 176, . . Saunderson . October, 1726, at Lisbon, vii. 203, .... Carbone October, 1725, at Pekin, vii 273, Koghler February, 1729, Carrickfergus, vii. 352, . . Dobbs Rome, vii. 363, Carbone ■> Paris, vii. 364 Padua, ibid Poleni, July, 1729, Wirtemberg, ibid, Weidler Padua, ibid, Poleni Bologna, vii. 377, Manfredi Rome, ibid February, 1730, Lisbon, vii. 418, Carbone August, 1728, Pekin, vii. 419, February, 1729, Pekin, vii. 440, Carbone July, 1729, Barbadoes, vii. 485, Stevenson June, 1721, New England vii. 530, Robie December, 1732, Rome, vii. 609, . . Revillas, &c. — _ London, ibid, Graham October, 1735, Wittemberg, viii. 96,. . Weidler March, 1736, London, viii. 116 Graham . Greenwich, ibid, Halley ■ ■ London, ibid, Celsius « London, viii. 117, Bevis .. Somersetshire, viii. 118, . . Milner — transit by Aldebaran, April, 1736, viii. 146, .... Bevis — eclipse, September, 1736, London, ibid, Graham & Bevis ■ Wittemberg, ibid, . . Weidler — Hudson's Bay, ibid, Middleton — January, 1740, London, viii. 470, Short — — — December, 1740, Brasil, viii. 548, Legge .. New England, viii. 714, Winthrop October, 1743, London, viii. 715, .. ..Graham July, 1748, London, ix 567, Bevis at the Cape, March, 1718, vi. 414, — eclipses observed at Paraguay, ix. 6l5, 619, • • Sarmento — — July 14, 1748, at Madrid, ix. 620, Ulloa - 12, 1749, London, ix. 698, Bevis and Short . Huntingdonshire, ix. 6'99, Elstobb . December, 1749, x. 4, Maire June, 1750, London, x. 72, .... Catlin and Short Wittemberg, x. 94, Bose December, 1750, London, x. 9^>, Bevis, and Short November, 1751, London, x. 220, Short March, 1755, Elbing, x. 621, Barbosa Mar., 1755, Feb. 1757, Lisbon.xi. 158, Chevalier July, 1757, at Matritus, xi. 245, . . Wendlingen J July, 1757, at Lisbon, xi. 284, Chevalier November, 1760, at London, xi. 510, .... Short May, 1761, at Stockholm, xi. 560, ..Wargentin 1762, at London, xi. 632, Short ibid Bevis May and November, 1762, at Leyden, xi. 669, Lulofs November, 1762, at Calcutta, xii. 13, .... Hirst March, 1764, London, xii. 113, Bevis ________ Liverpool, ibid, Ferguson Brompton, xii. 114, ....Dunn Thorley, xii. 1 16, Raper Heidelberg, xii. 11.9, • - • • Mayer -- Vienna, xii. 221, .... Liesganig , 1769, Hawkshill, xii. 6ii7, Lind ■■ ■ , 1783, Paris, xv. 651, Zach Moore, Sir Jonas, biographical account of, ii. 81, . . . . Note Moors of Barbary, their food, and cookery, iv. 407, Jones Moose deer [cervus alces] account of, vi. 515, .... Dudley — of New England, and Virginian Stag, viii. 102, , . Dale I Morant, Rev. Philip, case of a boy who lost the malleus of each ear and one of the incuses, xi. 574 Moray, Sir Robert, biographical account of, ii. 106, . . Note — persons killed by subterraneous damps, i. 16 — method of extracting sulphur and vitriol from the mineral of Liege, i. 17 — extraordinary tides in the western isles of Scotland,!. 21 — machine for letting fresh air into mines, i. 27 — inquiries concerning tides, i. 113 — tables for the observation of tides, i. 118 — experiments for improving the art of gunnery, i. 165 — current of the tides about the Orcades, ii. 106 — description of barnacles, ii. 415 — of the island Hirta, ii. 41 6 — way of making malt in Scotland, ii. 469 Morbus strangulatorius, account of, x. 43, ........ Starr More, Henry, of the tides in the Gibraltar Straits, xi. 607 More, Robert, remarks in travels through Italy, x. 52 — manna collected from a tree in Italy, x. 52, 53 — bills of mortality of Holy-Cross, Salop, 1750-60, xi. 541 More, Samuel, case of the loss of use of the hands from cleansing brass wire, xi. 510 — similarity between the scoria of iron-works and some productions of a volcano, xv. 1 82 — of an earthquake in the N. of England, 1786, xvi. 176 Moreland, Sir Samuel, biograph. notice of, i. 67 0, . . Note — invention of the speaking trumpet, ibid — on raising water up heights, ii. 129 Moreland, W. success, operat. for hydrops pectoris, xii. 358 Morgan, Geo. Cad., on the light of bodies in combustion, xv. 668 Morgan. W. non-conducting power of a vacuum, xv. 699 — onsurvivorshipsandthe valuesof reversions, xvi. 475, 529 — -value of reversions after 3 lives, xvii. 72, 417, xviii. 576 Morland, Joseph, m. d., on secretions in the body, v. 1 — seminal power of the flower of plants, v. 68 Morley, Charles, m. d., a foetus voided per anum, iv. 155 Morne Garou, description of, xv. 634, Anderson Moro, A.nt. Lazzaro, on petrifactions, ix. 233 Morris, M. M. d., exper. on extracts of hemlock, xii. 120 — analysis of the Somersham mineral water, xii. 275 — native lead found in Monmouthshire, xiii. 369 Morrison, Robert, biograph. account of, i. 341, Note Mortality, on the greater mortality of males than females, xvi. 122, Clarke — see Life, Annuities, Survivorships. Mortality, (bills of) christenings and deaths in London, 1685, iii. 242 1686, 1687, 1688, iii. 420 — Births, marr., and deaths at Frankfort, 1695, iv. l69,Slare — &c. at the Old, Middle, and Lower Marck, 1690, iv. 4,1 0 in the dominions of Brandenburg, 1698, iv. 477 in Germany for 171 6, vi. 681, Sprengel — Freyberg, for a century, vi. 682, Same in Germany, &c, 1719, vii. 10, Same 1722, 1723, vii. 215, Same 1724, 1725, vii. 345, Scheuchzer of Dresden for 1617 to 1717, vii. 6*10, . . Sprengel Augsburg for 1501 to 1721, ibid, Same remarks on the bills of Dresden and Augsburg, ibid, Maitland at Stoke-Damerell 1733, viii. 53, Barlow of London, 16*26-35, viii. 258, Maitland of Bridgnorth, viii. 581, Stackhouse — of Bridgetown, Barbadoes, 1737-44, ix. 51 6, Clark — an improvement in the manner of registering, for the sake of calculating annuities, x. 223, Dodson k2 MOS INDEX. MOU Mortality (bills of) London 1704-53, x. 535, Braikenridge — of Great Shefford 1747-57, xi. 157 — Holy-cross, Salop, 1750-60, xi. 541, ... .More — of Madeira, xii. 475, Heberden — Holy-cross, Salop, 1760-70, xiii. 94; 1770-1780, xv. . go Gorsuch _ of Chester', Y772, xiii. 496, Haygarth; comparative table of the mortality of Chester, with that of London, Nor- wich, and Northampton, 498; bill of Chester, 1773, xiii. 595 ... . — of Warrington, 1750 to 1773, xni. 567, Aikin of Stockholm and the rest of Sweden compared, xiii. 684 tables of the proportional number of deaths in various cities, &c, xiv. 314, Haygarth — of Blandford forum for 40 years, xiv. 395, . . Pulteney _ of York, xv. 177, White — see Population. Mortar, method of making, at Madras, vii. 515, Pyke — see Gunnery. Mortification, successful use of bark in, vii. 572, . .Douglas _ — vii. 574, . . Shipton — xi. 159,. . Grindall of the limbs of a whole family, xi 626, 646, Wollaston particulars of the diet and manner of living of the family, xi. 628, Bones — see Gangrene. Mortimer, Cromwell, m. d., uncommon anastomosis of the spermatic vessels, vii. 420 — of Le Blon's method of printing in imitation of painting, and of weaving tapestry, vii. 477 — on the poison of laurel- water, vii. 494 — dissection of a female beaver, vii. 623 — experiments on persons bitten by vipers, viii. 84 — account of electrical experiments of Mr. Gray, viii. 110 — remarks on the raonoculus apus, viii. l6'3 — an antique stamp ; of Roman stamps, viii. 248 Mr. Wheeler's electrical experiments, viii. 313 — cause of letters found in the middle of trees, viii. 36l — account of D. Stuart's paper on the heart, viii. 483 — an aurora australis 1739, viii. 525 — a beetle alive in a cavity of sound wood, viii. 535 — a fish's horn stuck into a ship's side, viii. 536 — collection of Frobenius's papers on ether, ibid — on the polypus, viii. 623 — on the natural heat of animals, ix. 148 — meteor seen December 1742, ix. 168 — distemper among the cattle 1745, ix. 171, 177, 184 — remarks on the turquoise, ix. 324 — a new metalline thermometer ; construction of thermo- meters, &c , ix. 397 — of a person born with two tongues, ix. 484 — small pox on a child two days old, ix. 692 — description of the zeus luna, x. 70 — a curious non-descript fossil, x. 106 — a small spheroidal stone with lines, x. 11. 7 Morton, Earl of, solar eclipse observed at Edinburgh, ix. 591 — hydrophobia cured with vinegar, xii. 221 Morton, Chas, m. d., biographical account of, x. 219, Note — cause of muscular motion, ibid — generic character of the limpet fish, xi. 313 — connection of the Ch nese and Egyptian character, xii. 685 Morton, Rev. John, fossil shells in Northamptonshire, v. 284 Morton, Rich., m. d., biographical account of, iii. 534, Note Mosaic work, see Antiquities. Moscow, longitude of, iii. 421 Moslyn, Sir Roger, damp in a coal mine, ii. 398 Moss, on the manner of seeding of, ix. 200, Hill — on the vegetation of plant* in, ix, 468, Bonnet Moss, of the various species of, xi. 246, Watson Mosses (Peat) in Scotland, ace. of, v. 633, E. of Cromartie — a moving moss in Lancashire, ix. 106, Richmond — irruption of solway moss, Dec. 1772, xiii. 304, Walker Mostyn, Sir Thomas, a Roman torques of gold, viii. 550 Motion, of the general laws of, 1. 307, Wallis — Wallis's treatise on, i. 410, 471 — of even, languid, and unheeded, iii. 153, Boyle — observation relative to a law of, xii. 227, Franklin — on the quantity of impelling powers, xiv. 72, Smeaton — effect of friction on, xv. 654, Vince — of spherical motion, • xvi. 740, Wildbore — see Projectiles, Gravity. Motion (astronomy) see Moon, Planets, SfC. Motion (mechanics) on the vibration of watch balances, xvii. 380, Attwood — effect of friction on motion, xv. 654, Vince — see Motion (Force of Moving Bodies.) Motion (perpetual) explana. of a tract on, iii. 240, 315, 349, Papin — on the attempts towards finding, vi. 542, . . Desaguliers Motion (force of" moving bodies) law of collision, i. 310, Wren ; 337, Huygens — on the fall of bodies, v. 6l2, Hauksbee — falsity of the common opinion on, vi. 570, . . Pemberton — degree of momentum of moving bodies, vi. 632, 638, Desaguliers — in collision with non-elastic bodies, vii. 166, .... Eames — nature of the force of moving bodies, vii. 169, . . Same — on the same subject, vii. 203, Same — on the controversy respecting, vii. 219, Clarke — Gravesande's experiments on, vii. 6l8, .... Desaguliers — experts, to decide the controversy on, ix. 128, .... Jurin — of a body deflected by two forces tending to two fixed points, xii. 608, Robertson — new theory of rotatory motion, xiv. 144, Landcn — communica. of, by impact and gravity, xiv. 368, Milner — principles of progressive and rotatory, xiv. 726, . . Vince — fundamental experiments on collision, xv. 295, Smeaton — theory of the motion of fluids, xvii. 466, Vince Mouldiness, vegetation of, on a melon, vi. 257, • . Bradley — of the green mould on fire-wood, x. 8, Miles Moulin, Allen, m. d., quantity of blood in men, iii. 417 — injection of mercury into the blood, iii. 436 — experiments on shining sand from Virginia, iii. 495 — anatomical observations on the heads of fowls, iii. 531 Moulins, S. des, m. d , of a mineral spring at Canter- bury, v. 375 Moult, J., new method of preparing salep, xii. 589 Mounsey, James, m. d., biograph. account of, ix. 460, Note — foetus 13 years in the Fallopian tube, ibid — of the everlasting fire in Persia, ix. 503 — of the animal producing castor: geological account of Bohemia j of the baths and mineral waters at Carlsbad; tin mines of Schlachtenwald ; manufacture of vitriol at Geffries, ix. 688 — poisonous effects of an effervescent mixture, xi. 66, xii. 83 Mountaine, W., on a periodic review of magn. varia. x. 556 — tables of magnetic variations 1700 to 1756, xi. 149 — on the construction of maps, &c, xi. 218 — effects of lightning on metals, xi. 393 — defence of Mercator's chart against West, xi. 697 — on some observations of magnetic variation, xii. 336 Mountains, table of heights of several, vii. 283, Scheucbzer — in Siberia, heights of, ix. 491, Gmelin — in S. America, and the Glaiceres in Savoy, height of, ix. 492, Note — origin of considered, xi. 11, Wright MUS INDEX. MYL 77 Mountains, conjectures respecting the written mountains at Sinai, xii. 283, Montagu — in N. Wales, compar. height, xiv. 148, Note, Barrington — cause of the coldness of the summits of, xvi. 375, Darwin — see Vesuvius, JEtnat Gletscher, Schihallkn. — see Barometer, Heights. Mouse, see Mice. Moxa, preparation and use of, at Japan, ii. 632 Mozart, the musician, early genius of, xiii. 11, Barrington Mudge, John, m. d., biographical account of, ix. 625, Note — lateral operation for the stone improved, ibid Mudge, J., on making and polishing the metals of reflecting telescopes, xiv. 157 Mudge, Wm., see Trigonometrical Survey. Mulberry tree, the white sort preferable to the black, i. 31 — method of propagating in Virginia, i. 66 Mullen, — — , m. d., dissection of a double kitten, Hi. 209 Muller, Geo. Fred., description of some bivalve insects, (monoculi), xiii. 132 Muller, John, biographical notice of, viii. 144, .... Note — of his book on conic sections, &c, viii. 145 Mullineux, — , m.d., large stone voided per urethram, iii. 552 Multinomial to raise an infinite to a given power, iv. 176, Demoivre — on the fluents of multinomials, vi. 513, Simpson Mummy, examined in London, descrip. of, xii. 77, Hadley •— observations on opening several, xvii. 392, Blumenbach Munckley, Nich., m.d., efficacy of bark in fever, xi. 235 — account of the comet of 1759, xi. 337 1760, xi. 428 Mural quadrant, an improved astronomical, ix. 347, Gersten Muraltus, — , of the ice mountains of Helvetia, i. 365 Murdoch, P., d. d., case of a cartilaginous stomach, ix. 632 — mean motion of the moon's apogee, x. 138 — trigonometry abridged, xi. 210 — of the best form for maps, xi. 2 1 5 — of refracted rays made colourless, xi. 718 — rule for determining the moon's parallax, xii. 87 — connection betw. the solar and lunar parallaxes, xii. 500 Muriatic acid, see Acid. Murrain in cattle, see Distemper. Murray, Mungo, observ. of the solar eclipse, 1764, xii. 120 Mus Alpinus, see Marmot. Musa, on the family of plants, so called, vii. 422, Garcin Muschenbroek, P. Van, m,d., biog. account of, vii. 105, Note — Ephemerides Meteorological, vii. 56*5, 571 — experiments on Indian magnetic sand, vii. 647 Muscle (fish), microscopical observ. on, v. 703, Leuwenhoek — the salt and fresh-water muscle of Pennsylvania, ix. 70, Bartram Muscles (anatomy), on their nature, i. 433, Willis — on muscular motion, ii. 148, Mayo — on the carneous filaments of, ii. 401, .... Leuwenhoek — on the structure and contraction of, ii. 49-3, .... Dr. C. — on the motion and use of, ii. 499. 577, Borell — instance of the power of distorting, at pleasure, iv. 294 — of the neck, remarks on, iv. 368, . . Dupre and Cowper — frame and texture of, vi. 82, Leuwenhoek ■■ vi. 84, Muys — observations on the membrane of, vi. 502, Leuwenhoek — — — muscular fibres of animals, vi. 504, 576, Same " ■ fish, vi. 523, Same — muscular motion, cause of, x. 219, Morton — case of ossified muscles, xi. 335, 542, Henry — on muscular motion, xvi. 36l, Fordyce — nature and use of the muscles of the eye, xvii. 453, 660, Home — on muscular motion, xvii. 525, Samejj Muscles (anatomy) on the morbid actions of the straight muscles of the eye, xviii. 74, Home — disordered by an habitual unvaried action, xviii. 76, Same — see Flesh, Galvanism, Electricity, (Medical J. Musgrave, Wm., m. d., biographical notice of, ii. 66l, Note — on cutting out the ccecum of a bitch, ibid — experiments on digestion, iii. 72 — experiments on the lacteals, iii. 102 — cause of the necessity of respiration, iv. 270 — passage of liquor injected into the thorax, iv. 271 — of the extraordinary size of Edmund Melloon, iv. 273 — case of a periodical palsy, iv. 293 — of a piece of Saxon antiquity, iv. 341, 469 — advantage of the practice of laryngotomy, iv. 448 — a polypus found in a dog, iv. 525 — a periodical haemorrhage of the thumb, iv. 586 — experiments of injecting the lacteals, iv. 632 — of hydatids voided by stool, v. 179 — jaundice by a stone obstructing the biliary duct, v. 292 — remedies for the gout, v. 362 — account of the Roman legions, vi. 17 - eagles, vi. 39 — inscriptio Tarraconensis, v. 42 — Britain formerly a peninsula, vi. 293 Musgrave, Sam., m.d., proper shape of lightning con- ductors, xiv. 440 Mushroom, descrip. of the agaricus piperatus, ii. 33, Lister — flower and seed of, ii. 1 82, Same — observations on the seeds of, viii. 718, Pickering — remarks on Mr. Pickering's papers, viii.721,ix.4lWatson — culture of, ix. 31, Pickering — see Fungus. Music, comparison of ancient and modern, ii. 62 — theory of, and of sound, ii. 379 — the trembling of consonant strings, ii. 380, .... Wallis — on the notes of the trumpet, iii. 46'7, Roberts — natural grounds of harmony, iii. 624, Holder — division of the monochord, iv. 240, Wallis — imperfections in an organ, iv. 287, Same — of the ancient canons of, iv. 288, Same — on ancient music and its effect, iv. 305, Same — theory of, reduced to proportions, v. 243, .... Salmon — genera and species of the music of the ancients, ix. 268 Pepusch — machine for writing extempore voluntaries, ix. 332, Freke — of a person not musical singing well during a delirium, ix. 370, Doddridge — see Instruments, (Musical) Musicians, of the early genius of Mozart, xiii. 11, Barrington Handel, 13 Same W. Crotch, xiv. 513, Burney — instance of early musical genius, xiv. 519> Same Musk, produced by the musk-deer, ii. 356, .... Tavernier — use of, in convulsive disorders, ix. 89, Wall — cases of the successful use of, ix. 9L Reid — instances of the medicinal virtue of, ix. 207, . . Parsons Musk-quash, on the scent of, ii. 309 Musk hog, anatomy of, ii. 668, Tyson — description of, ibid, Note Musk-scented insects, account of, i. 6 17, Ray i. 645, 649, Lister Mustel, M., experts, and observs. on vegetation, xiii. 399 Mustela fossilis [cobitis] figure of, ix. 335, .... Gronovius Muys, Mr., frame and texture of the muscles, vi. 84 Myddleton, Starkey, m. d., an extra-uterine foetus, ix. 112 — foetus 16 years in the abdomen, ix. 373 Mylius, — , observations on the sex of flowers, x. 176, — collecting of electricity during thunder, x. 298 78 NEE INDEX. NE W Myopes, use of telescopes without eye-glasses, vi. 424, Desaguliers Myrrh, observations on that from Abyssinia, xiii. 672 N Nadi, Jos. Anthony, solar eclipse, 1718, at Bologna, vii 21 Naevus Maternus, an extraordinary, vii. 100,.. Steigerthall Nairne, Edward, equatorial portable observatory, xiii. 104 — experiments on dipping needles, xiii. 360 — electrical experiments, xiii. 498 specific gravity of water from sea-ice ; and on the freez- ing of sea-water, xiv. 35 — experiments on Smeaton's and other air-pumps, xiv. 220 — advantage of pointed lightning-conductors, xiv. 426 — effect of electricity in shortening wire, xiv. 688, xv. 388 Naisb, Edward, ossification of the crural artery, vi. 539 Napellus, case of a man poisoned by, vii. 642, .... Bacon Naphtha, a sort of, found in Italy, i. 672 — combustibility of, ii 168 Nardus Indica, see Spikenard. Narhwal, see Unkorn-Jish. Natron, and nitre, account of, iii. 50, Leigh — a pure native sort, in Tripoli, xiii. 21 6, Monro Natural History, heads for the natural history of a country, i. 63, Boyle — observs. of nat. hist, in Wales, v. 676, 677, 693, Lhwyd Ireland, v. 694, 700, Same Wales and Scotland,vi.l9,73,Same ■ Yorkshire, vi. 45, . . Richardson New England, vi. 85, . .Mather Natus, Peter, an orange grafted on a citron stock, ii. 213 Navel, of a foetus voided from the, iv. 173, Brodie — another case of the same, iv. 6*34, Birbeck — a rupture of the, ix. 41, Taube Navigation, problems in, i. 69, Mercator — outlines for a complete treatise on, iii. 511, Petty — machine for measuring a ship's way, vii. 126, 338, Saumarez — sounding depths, ix. 228, Cock — measuring a ship's way, x. 457, Smeaton — chief prob. in nautical astronomy xviii. 95, Mendoza Rios — see Ships. Nautilites, descrip. of a fossil nautilus, ix. 510,. . Lyttleton ix. 632, .... Baker Neagb, see Lough Neagh. Neale, Thomas, sad effect of thunder and lightning, i. 84 Nebulae, account of, vi. 205, Halley — appearance of the nebulous stars, vii. 602, .... Derham — a nebula in Coma Berenices, xv. 37, Pigot — observations of 1000 new nebulae, xvi. 158, 586,Herschel — on the nature of nebulous stars, xvii. 18, Same Neck, see Tumours, Needham, John, part of the intestines cut out, x. 6l2 Needham, Walter, m. d., biog. notice of, i. 177, ..Note — on the human and animal foetus, i. 183 — on the pretended discovery of a communication between the thoracic duct and the emulgent vein, i. 736 Needham, Turberville, of the chalk called malm, viii. 729 — observ. on the farina of the red lily, viii. 731 — worms discovered in smutty corn, viii. 732 — electrical experts, by M. Le Monnier, ix. 262 — description of Buffon's burning mirror, ix. 344 — generation, composition, and decomposition of animal and vegetable substances, ix. 604 — on the nature of asbestos, xi. 494 Needle, thrust into the arm came out at the breast, viii. 504 Needle, (magnetic) on the inclination of the, ii. 78, Bond Needle (magnetic) tendency to iron held perpendicular at the Line, iii. 232 — observations made near the Cape, iv. 500, Cunninghame — variation of the horizontal needle, 1723, vii. 27, Graham — observ. in London on the dipping needle, vii. 94, Same — unusual agitation of, vii. 463, Hoxton — affected by the cold, viii. 224, Middleton — declination at Churchill river, viii. 597, Same — obs. of the dip in the South sea, xiii. 177, Green & Cook — on dipping needles made byMr.Mitchell, xiii 36o,Nairne — of a new dipping needle, xiii. 593, Lorimer — expts.on the dipping needle, xiii. 6l3, xiv.22, Hutchins — descrip. of the dipping needle used by the r. s., xiv. 56, Cavendish — obs. of the dip in London for sev. years, xiv. 58, Same — new suspension of the needle, xiv. 589, Ingenhousz xvii. 142, ...Bennet — see Magnet. Negroes, remark on the colour of, ii. 229, Towns — of a spotted negro, iv. 221, Byrd — change of colour in a negro-woman, xi. 370, .... Bate — instances of white negroes, xii. 190, Parsons Neil, Wm. biographical notice of, ii. 1 12, Note — the inventor of a right line equal to a curve, ii. 112 Nelson, Jos. effects of a storm of thunder and lightn. v.432 Nephrotomy, case of successful practice 'of, iv. 116 — remark on the danger of attempting, iv. 117, ... . Note Nerves, micros, observations on the optc nerve, ii. 222 • i'i. 591, Leuwenhoek — existence of a fluid in the, vii. 550, Stuart — on the action of, vii. 578, Same — experts, on the nerves and their reproduction, xvii. 512, Cruikshank — experiments on their reproduction, xvii. 519, Haighton — observations on the structure of, xviii. 430, .... Home Nesbitt, Robt., m. d., of a subterraneous fire, vii. 195 Nests, curious wasps' nests of Pennsylvania, ix. 123, Bartram — descrip. of an American wasp's-nest, x. 607, Mauduit Nettis, John, configurations of snow particles, xi. 1 Nettleton, Thos., m. d., of inoculation in Yorks.vi. 564,568 — mortality of the natural small-pox compared with the inoculated, vi. 608 — height of the mercury at different elevations, vii. 86 Newman, Caspar, biograph. account of, vii. 93, .... Note — distillation of camphor from thyme, vii. 93, 631, — proving of French Brandy, vii. 120 — on fixed alkaline salts, vii. 128, 132 — nature and properties of ambergris, vii. 660, 668 Neve Peter Le, urns dug up in Norfolk, vi. 65 — sinking of oaks in the ground, vi. 348 — an aurora australis March 1739, viii. 526 Neve, Rev. Tim. parhelia and aurora borealis, viii. 135 Nevill, Francis, ancient urns, &c. in Ireland, vi. 63 — observations on Lough Neagh, vi. 67 — ancient trumpets, &c. found in Ireland, vi. 71 — of a marble quarry in Ireland, vi. 75 — of large teeth dug up in Ireland, vi. 199 New England, of destructive insects at, i. 49., .... Winthrop — observations on the natural history of, iv. 267, Bullivant vi. 85, . . Mather — progress of cullivation at, vii. 57> Dudley New Holland, on the natural history of, iv. 3 J 6, . . Witsen Newland, Chas., chart of the red sea, xiii. 286 — remarks on a journey to Judda and Mocha, xiii. 287 — method of distilling fresh from salt water, xiii. 289 — cause of white spots in the Eastern sea, xiii. 290 Newman, Henry, of inoculation in New-England, vi. 563 Newton, Jas-, effects of the chelidonium glaucium, iv. 295 NOO INDEX. OLD 79 Newton, Sir Isaac, exper. on light, and theory of, i. 678 — invention of a catadioptric telescope, i. 691, 6*95, 703 — apertures, lengths, &c. for telescopes, i. 704 — answer to, objections to his telescope, i. 705 — on a reflecting telescope by M. Cassegrain, i. 71 1 — trial of experts, proposed, for his theory of light, i. 714 — on Pardies' animadversions on his theory, i. 730 — queries for experts, on his theory of light, i. 734 — reply to a 2d letter of Pardies, i. 740 — answer to Hook, on his theory, ii. 13 — reply to a letter from Paris on his theory, ii. 86, 91 — reply to remarks by Linus on his theory* ii- 26 1, 263 — particular answer to Linus, ii. 276 — on Lucas's exceptions against bis theory, ii. 338 — solution of two problems of Bernoulli, iv. 129 — his low pecuniary circumstances, iv. 641, Note — account of the invention of fluxions, vi. 1 16 — problem concerning curves, vi. 211 — account of his Chronological Index, vii. 89 — defence of his Chronological Index, vii. 172, 191, Halley — a reflecting instrument for taking the moon's distance from the stars at sea, viii. 590 Newton's binomial theorem, demonstrated, viii.571,Castilion ■ - - — — x. 127,. . Simpson ■ xviii.33, . . Sewell Niagara river, account of the falls of, vi. 574, .... Dudley Nicholls, Frank, it. d., biograph. account of, vii. 231, Note — on a natural history of mines, vii. 224, 248 — nature and cause of aneurisms, vii. 231 — on the effect of the lungs upon blood, vii. 3^1 — dissection of an hermaphrodite lobster, vii. 398 — on the veins, &c. of leaves, vii. 419 — a polypus coughed up by an asthmatic person, vii. 481 — of worms in animal bodies, x. 6l6 — observations on dissecting the body of George II. xi. 574 Nicholson, Mr., a remarkable storm of lightning, xiii. 538 Nicholson, D., on the scurvy-grass of Greenland, viii. 391 Nicholson, Wm., Runic inscriptions, iii. 254- — arrangement of logarith. lines on instruments, xvi. 262 — an electrical machine without friction, xvi. 505 — experiments and observations on electricity, xvi. 599 — Nicolini, Marquis, of Buffon's burning mirror, ix. 344 Nierop, D. R. Van, voyage to discover a m. e. passage to India, ii 171 Nightmare, cause and cure of, iv. 498, Chirac Nile, cause of the overflowing of, i. 85, Note Nitre, & nitro-aerial spirit, [oxygen] nature of, ii. 145, Mayo — and natron, account of, iii. 50, Leigh — remarks on the nitre of Egypt, iii. 108, Lister — phlogistication of the spirit of, xvi. 557, Priestley — of its action on gold and platina, xviii. 139, • - . Tennant Nitrian water, experiments on, ii. 50, Leigh Nitrous acid, on the production of, xvi. 6"06, Milner Nitrous air, early discovery of nitrous gas, ii. 241 — on the production of, xvi. 606, Milner Nixon, John, antiquities found at Herculaneum, xi. 85 — description of the temple of Serapis, at Pozzuoli, xi. 106 — antiquity of glass in windows, xi. 233, 539 — remarks on some antiquities in Italy, xi. 473 Nolana prostrata, description of, xi. 708, Ehret Noli Me Tangere (disease,) see Cancer. Nollet, J. Anthony, biographical notice of, viii. 223, Note — experiments on ice, ibid. — effects of electricity on animal and veget. bodies, ix. 473 — electrical experiments in Italy, x 20 — account of the Grotta de Cani, x. 1 37 — to extract electricity from the clouds, x. 295 Nooth, J. M., m. v., improv. in the elect, machine, xiii. 456 Nooth, J. M., m.d., to impregnate water with fixed air, xiii. 487 Norfolk, strata of the cliffs on the coast of, ix. 272, Arderon — ■ subterraneous caves in the chalk-hills of, ix. 490, Same Norris, Henry, of English weight and measure prior to Henry Vllth. xiii. 582 North-east passage, voyage to discover a, ii. 17 1, . . Nierop — history of several attempts to discover, ii. 233 Norwood, Richard, biographical notice of, i. 206, .... Note — of the tides, water, & whale-fishing, at Bermudas, i. 206 — his admeasurement of a degree on the meridian defended, xi. 593, Raper ; reply by M. De Lalande, xi. 594 Norwood, Rich., Jun., observ. at Jamaica, viz. on alligators, tortoises, chegoes, shining flies, manchenille apple, i. 295 Nose, anatom. observ. on the structure of, ii. 432, Verney Nourse, Edward, case of hydrophobia, viii. 113 — stones in the coats of the bladder, viii. 545 Nourse, Charles, cure of wounded intestines, xiv. 63 Nova Zembla, description of, not an island, ii. 124 Nuck, Anthony, biographical account of, iii. 242, . . . Note — on a new salivary duct, &c. iii. 241 Nutmegs, of the growth of, ii. 356, Tavernier — microscopical observations on, iii. 591,. . . . Leuwenhoek Nux vomica (ignatia amara) medicinal virtues of, iv. 356, Johannes — further particulars of the same, ibid, Camelli Nyctanthes elongata, description of, xiii. 147, Bergius Nyl-ghau, [white footed antelope,] description of, xiii. 117 Hunter O Oak-trees, of dwarf oaks in Connecticut, i. 421, 442, Winthrop — a new species of oak, xiii. 306, Holwell Object glasses, proportions of the apertures, i. 22, . . Auzout — improved method of making, i. 298, Mancini — on grinding of hyperbolical glasses, i. 353; engine for, 396, Wren — to remedy the defects arising from refrangibility of light, xi. 267, Dollond — account of his improvement in, xii. 19+, .... P. Dollond — method of working the spherical, xii. 691, Short — see Telescopes, Microscopes, Optic Glass, &c. Observatory, difference of longitude of the Greenwich and Paris observatories, xi. 7 13, Short — of Tycho Brahe's observatory, iv. 525, Gordon — of the Bramin's, at Benares, xiv. 217, Barker — on the relative positions of the observatories at Paris and Greenwich, xvi. 218, Maskelyne — of Geneva, convenient for measuring an arc of the meridian, &c, xvii. 34, Pictet — descrip. of the Benares observatory, xvii. 291, Williams Occultation, see the different planets, &c. Ocean, on a conjunction of, with the Euxine Sea, i. 15 Oenanthe crocata, poisonous qualities of, iv. 242, Vaughan ix. 256, Watson — taken by mistake instead of water-parsnep, the medicinal effects of, xiii. 357, Pulteney Oil, of oils that effervesce and explode with or without flame, iii. 063, Slare — ascent of between planes, v. 659 > suspension 679, Hauksbee — of sassafras crystallized, viii. 243, Maud — from the arachidna of North Carolina, xii. 665, Watson Oldenburg, Henry, some account of, i. 1, Note — of conveying liquors into the mass of the blood, i. 45 — a dropsy acquired by being constantly in the operrair, i. 49 — of a propensity in a young girl to eat salt, i. 49 80 ORT INDEX. PAD Oldenburg, Henry, on the medical effects of friction, i. 67 trials of transfusion of blood ; circumspection recom- mended, i. 183 — trials of transfusion at Paris, i. 204, Ombrometer, see Rain-gage. Oliver, Andrew, of an extraordinary sickness among the Indians at New England, 1763, xii. 170 Oliver, W., m. d., pressure of water at several depths, iii. 585 of an ebbing and flowing well near Torbay, ibid curiosities seen in Denmark and Holland, v. 45 account of a calenture [phrenitis] v. 104 — of the Peruvian bark tree, v. 1 19 — case of extraordinary sleepiness, v. 277 genitals of a woman preternaturally formed, vi. 673 — cases of dropsies cured by sweet oil, x. 567 Omentum, dissection of a child without, vi. 307, Blair — case of a very large omentum, vii. 17» Huxham Opal, method of counterfeiting opal, i. 270, Colepresse Ophidium barbatum, description of, xv. 134, . . Broussonet Ophris, lilifolia, description of, xi. 701, Ehret Opium, use of, by the Turks, and effects, iv. 101, . . Smyth — a great quantity taken without sleep, iv. 634 Opossum, anatomy of the, iv. 248, v. 105, Tyson — anatomy of the male, v. 1 1 1, Cowper Optics, to make the picture of any object appear on a wall. i. 269, Hook — observations on Iceland crystal, i. 545, Bartholin — Alhazen's problem solved, ii. 97 problem why 4 convex glasses in a telescope make ob- jects appear erect, iii. 329, Molyneux — cause of the apparent greater magnitude of the sun and moon, when near the horizon, than when more ele- vated, iii. 365, Molyneux j opinion on the same sub- ject, iii. 369, Wallis — optical experts, before the r. s., vii. 292, . . Desaguliers — on the apparent increased size of the sun and moon near the horizon, xi. 6l 1 , Dunn — difference of reflection from water and air, xii.4, Edwards — observ. on horizontal refractions, xviii. 86, .... Huddart — double images by atmospherical refraction, xviii. 667, Wollaston — see Light (Optics) . Optic glasses, improvement of, i. 2, Campani • , on rock crystal for, i. 134, Divini — account of Mr. Smethwick's, i. 226 — polished by a turn-lath, i. 284 — of a natural lens of water, iv. 166, Gray — on the application of telescopic sights, vi. 295, Derham — combination of lenses with reflecting planes, viii. 54 — see Object Glasses, Telescopes, Microscopes, &c. Optic nerve, microscopical observs. on, ii. 222, Leuwenhoek — see Eye. Opuntia, its effect in colouring the juices of animals, xi. 137, Baker Oram, R., convulsions cured by a discharge of worms, xi. 203 Orang outang, organs of speech of the, xiv. 503, . . Camper Orange-tree grafted on a citron, fruit of, ii. 213, . . Natus Orcades, current of tides about the, ii. 106, Moray Ores, chemical examinat. of, xiv. 585, Fordyce and Alchorne Organ, on the imperfections in an organ, iv. 287,. . . .Wallis Orkney islands, some particulars of, iv. 487, .... Wallace Ornithorhyncus paradoxus, on the head of, xviii 746, Home Ornithology, notes, as additions to Mr. Ray's book, iii. 215, Lister Orred, Daniel, head of the os humeri sawed off, and motion of the limb preserved, xiv. 477 Orthoceratites, a remarkable specimen of, xi. 10, . . Wright — nature and origin of, ibid, Same Orthoceratites, description of a rare species of, xi. 26/, De Himsel Orthography, on an universal primer, iii. 314, .... Lodwick Osborne, John, success of inoculation at Boston, vi. 616 Oscillation, on finding the centre of, vi. 7, Taylor Os femoris, loss of a part supplied by a callus, v. 532, Sherman — another case of the same nature, viii. 326 ; another, viii. 503, Wright — remarks on a fracture of, vi. 263, Douglas — extraction of the bead of, viii. 620, Schlichting — reduction of, after luxation, xi. 482, White — another case, xi. 496, Young Os frontis, of a prodigious human, iii. 121, .... Molyneux Os humeri, its purpose supplied by a callus, v. 378, Fawler — head of, come away by mortification, vi. 556, . . Derante — use of the arm retained after the loss of, xiii. 539, Bent — another case of, xiv. 477, Orred Os ilium, case of a fracture of, ix. 173, Layard Os pubis, death of Dr. Greene, by a fracture of, ix. 370,Cameron Ossification, and petrifaction of the arteries, v. 205, Cowper — of the crural artery, vi. 5 '9. Naish — of the tendons and muscles, xi. 335, 336, 542,. . Henry — of the thoracic duct, xiv, 684, 739t Cheston Ossory, Bp. of, of a Giant's Causeway in Scotland, xi. 533 Osteocolla, description of, i. 278, Beckman — cases of the medicinal virtue of, viii. 326, .... Sherman — nature of, ix. 126, Beurer Ostracites, a remedy in gravelly affections, iv. 355, . . Cay Ostrich, dissection of, ii. 534 Brown — anatomical description of, iii 393 — dissection of, vii. 69, Ranby vii. 150, Warren — observations on the dissection of, vii. 392, Ranby Otis minor [tetrax] account of, x. 452, Edwards Otter, observations on the anatomy of, ii. 291 — from Hudson's Bay [mustela lutreola] xiii. 326, Forster — anatomy of the sea- otter, xviii. 34, Home and Menzies Ova, see Eggs. Outram, Benjamin, singular balls of limestone found in cutting the Huddersfield canal, xviii. 30 Ovals, instrument for drawing and turning, xiv. 700. Ludlam Ovarium, case of dropsy in the left, ii. 437, Sampson — — — tumours in, ii. 501, Same foetus in, ii. 650, Maurice — dropsy in one of the ovaries, iv. 375, Sloane — dropsy in the, v. 31 8, Douglas — cure of dropsy in, vii. 2, Houstoun — tumour in, with hair, ix. 29, Haller — extraordinary case of dropsy in, xv. 625, .... Martineau — effect, on the prolific power," of extirpating one ovarium, xvi. 256, Hunter — on the formation of hair, &c. in the, xvi. 535, . . . Baillie Owl, several species from Hudson's Bay, xiii. 332, . . Forster Ox, of a preternatural substance cut from an, iii. 1 16, — micros, observ. on the palates of, v. 481, . . Leuwenhoek Oxford, philosophical society, specific gravities of grain, and various other bodies, iii. 138 Oxyoides [oxalis,] account of this family of plants, vii. 421, Garcin Oysters, account of shining worms in, i. 67, Auzout — microscopical observations on, iii. 481, . . . . Leuwenhoek — on stocking of the river Mene with, vi. 548, . . Rowland — and oyster-banks of Pennsylvania, ix. 70, Bartram — see Shells. Packer, Philip, a petrifaction on the trunk of an elm, i. 122 Paderborn, a remarkable periodical spring at, i. 45 P AR INDEX PAR 81 Paderborn, a periodical spring, with three streams of dif- ferent qualities, i. 47 Paderni, Camillo, statues and other antiq. at Herculaneum, viii. 435 ; x. 328, 493, 549, 585, 679 ', xi. 79, 236' Pagan temple, at Cannara, description of, v. 501, . . . Stuart Page, Sir Thomas Hyde, description of the King's Wells at Sheerness, Languard Fort, and Harwich, xv. 46 1 Painting, rules observed by ancient masters, i. 281 — conferences held at the Royal Acad, of Paris, for the im- provement of, i. 349; remarks on effect in several pieces of ancient masters, 350 — in wax, ancient method revived, xi. 4, Mazeas — remarks on the above discovery, xi. 6, Parsons — on the encaustic painting of the ancients, xi. 32S, 333, Colebrooke Paisley, Lord, observ. of the comet 1723, at Witham, vii. 15 Paitoni, J B., one of the lobes of the lungs wanting, xii. 199 Palates, of oxen, micros, observ. on, v. 481, . . Leuwenhoek Palilicius, see Aldebaran. Palitch, , observations of the star Algol, xv. 460 Pallas, S. Peter, m. d., of the cold at Berlin, 1762, xi. 694s — of a species of jaculator fish, xii. 322 — native iron ore of Siberia, xiv. 99 Palmer, Joseph, effects of lightning in Devonshire, x. 223 Palmyra, descrip., with journey from Aleppo, iv. 33, Halifax — two journeys from Aleppo to, iv. 49 — historical account of the ancient Palmyra, iv. 60, Halley — some particulars of the history of, iv. 122, Seller — the Palmyrene alphabet, x. 523, Swinton Palsy, Bath waters a cure for, iii. 140, Peirce — case of a periodical palsy, iv. 293, Musgrave — of a palsy in the eyelids, viii. 225, . . . . . Cantwell — efficacy of electricity in the cure of, xi. ld3, 262,Brydone xi. 189, .. . Franklin — ■ xi. 372, .... Himsel xii. 391, Spry Pantheon, at Rome, alterations making at, xi. 87 Panton, Paul, increase of population in Anglesea, xiii. 421 Papa, Jos. Del, poisonous effects of Indian varnish, iv. 608 Paper, portraits curiously cut in, v. 51, Ellis — sorts used by the ancients, vii. 491, Clerk — made from vegetables in China, x. 388,. . . . DTncarville — of a natural paper found in Tuscany, xii. 598,. . Strange — Hindostan method of manufacturing from the sun plant, xiii. 506 Papin, Denis, biographical notice of, ii. 239, Note — on the origin of fountains j supplying of rivers with water, ii. 242 — pneumatical experiments, ii. 239, Z$7, 271 — description of a siphon like the Wurtemberg, iii. 112 — new machine for raising water, iii. 193, 249, 34-*} re- marks on it by Dr. Vincent, iii. 239 — on a tract on perpetual motion, iii. 240, 315, 349 — shooting, by rarefaction of air, iii. 272 — - velocity with which air rushes into a vacuum, iii. 334 — improvement of the Hessian bellows, v. 226 — mechanic arts and physic of the East Indies, xi. 50 Pappus, ofAlexandria, two propositions of, restored, vi. 659, Simson Parabolic glasses, Du Son's progress in improving, i. 41 — description of Hoesen's mirrors, xii. 589> Wolfe Paracelsus, biographical account of, ii. 299> Note Paraguay, astr. observs. at, 1706 — 1736", ix. 6l5, Sarmento Parallax of the sun and moon, way of finding, ii. 447 — of altitude, theory, for the sphere, xii. 344.. . . . Mallet — of the sun and moon, connect, between, xii. 500,Murdock •*- on the menstrual parallax of planets, xii. 535, Smeaton — see Swn, Moon, Fixed Stars. Paraselenes, see Moon. Pardies, J. G., biographical account of, i. 726, Note — animadversions on Newton's theory of light, ibid — 2nd letter on the same subject, i. 738 Pareira Brava, medicinal virtues of, vi. 198, . . . . Helvetius Parhelia, of three seen at Paris at the same time, i. 73 — two seen in Hungary, i. 349, Brown — cause of, i. 459, Huygens — seen at Marienburg, ii. 130, Hevelius — seen at Sudbury, Suffolk, iv. 36 1, Peto Canterbury, iv. 367, Gray — unusual parhelion and halo, iv. 486, Same — unusual parhelia, and circular arches, iv. 664, . . Halley — observations of a parhelion, Oct. 1721, vi. 531, .. Same — and inverted rainbow, Oct. 1721, vi. 532, .... Whiston — in Ireland, March 1722, vi. 582, Dobbs — at Kensington, March 1727, vii. 186, Whiston — Huntingdonshire, Dec. 1735, viii. 134, Neve — the same at Wittemberg, viii. 136, Weidler — of three seen in London, Sept. 1736, viii. 137, Folkes — one observed in Norfolk, July 1749, ix. 684, . . Arderon — an anthelion seen near Oxford, xi. 532, Swinton — a meteor resembling a parhelion, xii. 39, Dunn Paris, of an observatory building at, i. 6l6 — comparative magnitude with London, iii. 320, 342, Petty — regulations of Royal Acad, of Sciences, iv. 374, Geoffroy; first institution of, ibid, Note — proceedings of Royal Acada. of Sciences, iv. 651, Blondel — on its size, compared with London vii. 228,. . — . . Davall Parisi, Wm , Caesar, lunar eclipse 1718, at Bologna, vii. 21 Parker, Lord, agita. of the waters in Oxfordshire 1755, x. 65% Parker, John, eruption of Vesuvius, 1751, x. 270 Paroquet, dissection of a, iii. 650, Waller Parr, Thomas, account of, and dissection, i. 319, Harvey Parsons, James, M. v., biograph. account of, vii. 6*92 Note — account of his book on hermaphrodites, viii. 477 — account of Le Cat's " Traite des Sens," viii. 619 — account of the sea-calf [phoca barbata] viii. 658 — natural history of the rhinoceros, viii. 692 — observations on several sorts of seed, ix. 80 — description of the Indostan antelope, ix. 145 — minute crystal stones, ix. 147 — medicinal virtue of musk, ix. 206 — on burying, in lime, cows dead of distemper, ix. 255 — of Marg. Cutting, who could speak without a tongue,ix. 375 — a shell fish lodged in a large stone, ix. 438 — two conjoined female children, ix. 568 — description of the frog-fish, [lophius piscatorius] ix. 658 — of the phocas marinse, x. l6l — description of an hermaphrodite, x. 170 — of the striated monkey [simia iacchus] x. 171 — on the casting of shells of crabs, x. 254 — formation of corals, corallines, &c, x. 282 — Kircher's opin. of the burning-glass of Archimedes, x. 488 — use of lycoperdon as a styptic, x. 566 — remarks on a petrified echinus, x. 594 — a sheep with a preternatural horn, x. 6*01 — on a revival of painting in wax, xi. 6 — extraordinary tumours on the head, xi. 155 — fossils found in the Isle of Shepey, xi. l65 — description of the felis caracal, xi. 474, and Note pholas conoides, xii. 174 — account of a white negro, xii. 190 — of the double horn of the rhinoceros, xii. 2?6 — observations on amphibious animals, xii. 324 — peculiar structure of the wirid-pipe of several birds 3 and of the land tortoise, xii. 329 — a particular species of chamaeleon, xii. 552 L 82 PEL INDEX. PER Parthian coin, — see Coins. Partington, Miles, cure of muscular contraction by electri- city, xiv. 302 Partridge from Malacca [tetrao porphyrio] description of, xiii. 267, Badenach Parturition, delivery though the vagina was closed up, iv. 234 — dissection of a woman dead in, iv. 56*0, Silvestre — calculation of accidents attendant on 5 proportionate num- ber of twins, monstrous births, &c. ; proportion of male and female children, xv. 118, Bland Paschal, J., analogy of tides and the motions of disease, iii. 551 Passion flower, on the farina fcecundans of, ix. 234, Badcock Patagonia, account of the inhabitants of, xii 391, •• Clarke . — . xiii. 7, . . Carteret Paterson, Wm., description of the tetrodon electricus, xvi.134 Patella, case of a supposed fracture of, vi. 466", . . Deverel Patella (fish) see Limpet. Patouillat, — , M. d., effects of the poison of henbane, viii. 267 Pavement, see Tessellated- Paul}, Latin translation of the Phil. Trans., 1669, i. 6'39 Paxton, Rev. Wm., effects of lightning on a church, xii. 6 10 Payne, John, on a steam engine, viii. 518 Payne, Robert, case of a fork thrust up the anus, vii. 125 Peacock, James, instrum. for drawing in perspective, xvi. 15 Peak, in Derbyshire, some account of, vii. 331, .. Marfcyn Pearce, Zachary, biographical account of, viii. 389, . . Note — account of Bell's history of Hungary, viii. 253 — — 1 reflections sur les anciens peuples, viii. 389 Pears, account of a double pear, iv. 470 Pearson, G., m.d., analyticalexpertimentson James'spowder, xvii. 87 — decomposition of fixed air, xvii. 221 — experiments and observations on white lac, xvii. 428 — experiments on the nature of wootz ; and observations on iron in its different states, xvii. 580 — description of some ancient arms and utensils, with ex- periments to determine their composition, xviii. 38 — nature of the gas produced by electrical discharges through water ; and process, xviii. 104 — experts, and observs. on urinary concretions, xviii. 254 Pearls, origin of, ii. 126 — the same, ii. 356, Tavernier — microscop. observs. on, and medicinal virtues of, v. 366, Leuwenhoek Pearl-divers, in the East Indies, i. 307, Vernati Pearl fishery, in the East Indies, i. 689 Baldaeus in the North of Ireland, iii. 512, . . Redding Peat, of the mosses in Scotland, v. 633, . . Earl of Cromartie — a preservative of dead bodies from decay, vii. 66*6, Balguy — a pit of peat moss in Berkshire, xi. 87, Collet Pebbles, account of some transparent, iii. 543, Lister — on the formation of, ix. 341, Arderon Pechlin, Joh. Nic. biograph. account of, ii. 321, .... Note Pecquet, John, biograph. notice of, i. 16*3, Note — of a communication of the thoracic duct with the emul- gent vein, i. 163, 736, ; obs. respecting it, 526, Note — on Mariotte's discovery respecting vision, i. 245 5 Ma- rio; te's reply, 443 Pediculus Ceti [lepas diadema] descrip. of, v 317, Sibbald Pediculus Pulsatorius, see Death-watch. Pedini, Pasqual R., earthquakes at Leghorn 1742, viii. 568 Peirce, Jeremiah, of a tumour in the knee, viii. 294 Peirce,R.M. d., effect of the Bath waters in palsy, &c.iii. 140 — of a shell in a woman's kidney, iii. 168 Pekin, latitude and longitude of, iv. 233, Cassini — plan of the city of, xi. 26*5, Gaubil Pelican, a species from Hudson's Bay, xiii. 347, . . Forster Pell, John, d.d., biographical account of, ii. 527, .. Note 586 Ellis Pell, John, d.d., improvem. of the mathema. sciences, ibid — answer to Mersenne's objections to the plan, ii. 532 Pelvis, unusual conformation of, ii. 449, Tyson — of a large glandular tumour in, viii. 158, .... Cantwell — of a bone found in a man's pelvis, xi. 476 Brady Pemberton, Henry, m.d., biograph. account of, vi.570, Note — on the force of moving bodies, ibid — solution of the prob. of Leibnitz and Bernoulli, vi. — on a secondary or reflected rainbow, vi. 624 — on a treatise of logarithmic solar tables, xi. 507 — on the locus for three and four lines, xii. 6"0 — to compute lunar parallaxes and eclipses, xiii. 181 — three astronomical problems solved, xiii. 349 Pen fish, description of the sea pen, xii. 41, .... Pendulum, motion of in vacuo, v. 172, Derham — to find the centre of oscillation, vi. 7, Taylor — to avoid the effect of heat and cold on, vii. 129, Graham — observ. with isochronal pendulums, vii. 649, . . Bradley — exper. on the vibrations of, viii. 6*0, Derham — affected by a centrifugal force, viii. 627, Poleni — to avoid the effect of heat and cold, x. 271, .... Ellicot — various inventions to avoid the irregularity, x. 283, Short — exper. on the lengths, at various places, xiii. 62, Mallet — account of a new pendulum, xvii. 336, Fordyce Pendulum watches, success of, for the longit. i. 7, Holmes — letter from M. Huygen's on the subject, i. 8 — structure and use of, ii. 79, Huygens Pendulum clocks, see Clocks. Penguin, descrip. of the aptenodyta patagonica, xii. 516, Pennant Penis, remarks on the, i. 272, De Graaf — case of hcemorrhage from, vi. 674, Howrmn Pennant, Thomas, biograph. account of, x. 6*88, .... Note — of coralloid fossil bodies, ibid — description of the Patagonian penguin, xii. 5l6 testudo ferox, and coiiacea, xiii. 141 — natural history of the turkey, xv. 32 — of earthquakes in Wales, xv. 85 Pennatula phosphorea, description of, xii. 41, Ellis Pen-Park Hole, description of, ii. 551, Southwell Pepper, see Pimienta. Pepusch, J. C, Mus.D., biograph. notice of, ix. 26s, Note — on the music of the ancients, ibid Perch, with crooked tails, in Wales, xii. 420, . . Barrington humped backs, in Dalecarlia, xii. 421, Note Percival, Philip, meteoric light at Dublin, vi. 455 Percival, Thos., M. D., biograph. account of, xiii. 355, Note — experiments on Peruvian bark, xii. 423 — observations on the Buxton and Matlock waters, xiii. 355 on the population of Manchester, xiii. 496, 659, xiv. 17 — a cheap method of preparing potash, xiv. 6*91 Percival, T. Roman stations in Cheshire and Lane. x. 197 — account of a double child, x. 233 Percussion, on the doctrine of, ii. 388, Marriotts on the force of, xii. 498, Richardson Pereyra, And., solar eclipse, 1730, at Pekin, vii. 500 Perks, John, quad, of the lunula of Hippocrates, iv. 452 — construction of a quadratrix to the hyperbola, v. 302 — division of the nautical meridian line, vi. 1S4 Periosteum, microscopical obsirv. on, vi. 4 84, Leuwenhoek Peritonaeum, watery cystises adhering to, viii. 492, Graham — a blind duct produced by the, x. 222, Le Cat Perpetual motion, see Muliun (perpetual). Perrault, Claude, biograph. notice of, ii. 202, Note — controversy with Mairiotte on vision, ii. 641 Perry, C, If. d., anal, of the water of the dead sea, viii. 555 ■ hot-spring near Tiberiades, viii. 556' — Hammam Pharoan water, ibid PHI INDEX. PIG 83 Perry, Mr. — , of die earthquake at Sumatra 1756, xi. 192 Perry, improv. in the manufacture, suggested, ix. 165, Miles Persepolis, unknown characters from the ruins of, iii. 543, Flower Persia, of some diseases in, ii. 344, Tavernier — art of damaskeening steel in, ii. 346, Same Perspective, doctrine of vi. 172, Taylor Peru, some particulars of the mineralogy of, ii. 168 Pescennius Niger, his hist, deduced from medals, x. 50, Boze Peters, Charles, m. d., case of hydrophobia cured, ix. 06' Peters, Nicholas, Jun., a boy shot through the lungs, ix. 6j Petit, Peter, some account of, i. 15, Note — on a conjunc. of the ocean with the Mediterranean, i. 15 Red Sea, ibid. — magnetical variations, i. 186 Petiver, James, biographical account of, iv. 132, Note — catalogue of plants of Guinea, iv. 201 — animals, plants, &c. from Maryland, iv. 324 — on similar virtues in plants of the same class, iv. 416 — description of some East Indian plants, iv. 527 — animals and shells from Carolina, v. 209 — list of fossil shells, &c. v. 259 — manner of making the storax liquida, v. 398 — catalogue of plants of the Chelsea garden, &c. v. 659, 667; vi- 17, 155, l68, 198, &c. — catalogue of Swedish minerals, vi. 49 Petre, Lord, extraordinary effects of lightning, viii. 583 Petrifaction, of wood without water, at Wendleburg, i. 38 — remarks on petrifactions, i. 119, Beale — on the trunk of an elm, i. 122, Packer — of rock plants, ii. 351, 647, Beaumont — of a petrified child seen in Denmark, v. 46, Oliver — petrified human bones, vii. 129, Scheuczer — cause of, & descrip. of those at Matlock, viii. 406, Gilks — bones incrusted with stone, ix. 181, Folkes — on those usually attributed to the deluge, ix. 233, Moro — of the petrifactions of Lough Neagh, ix. 282, . . . Simon ix. 2S8, Bp. Berkeley — a stratum petrified by the Matlock waters, xiii. 510 — an induration of sand, &c. on iron, xiv. 478, King — see Fossils, Shells. Petto, Rev. Samuel, parhelia seen at Sudbury, iv. 36l Petty, Sir William, biographical account of, ii. 172,. . Note — improvement of machines for land-carriage, iii. 62 — enquiries on the nature of mineral waters, iii. ()9 — experiments on the weight of various articles, iii. 113 — comparative magnitude of London and Paris, iii. 320, 342 — outlines for a treatise of navigation, iii. 511 Pewter money, coined in Ireland by King James, v. 199 Peyer, John Conrad, biographical account of, iii. 243 Note Peyssonel, J. Andrew, m. p., natural history of coral, x. 257 — of the brimstone-hill, at Guadaloupe, x. 700 — of the sea-currents at the Antilles, x. 710 — signs of the approach of hurricanes, x. 71 1 — account of a leprosy at Guadaloupe, xi. 74 — of a fish of the Antilles producing purple, xi. 225 — formation of sponges by worms, xi. 227 — description of the alga marina latifolia, xi. 241 — on the cause of earthquakes, xi. 245 — poisonous effects of the manchenille apple, xi. 284 — of the American sea-sun-crown, xi. 307. — - on the sea-millepes [terebella,] xi. 326 Phalana granella, generation of the, iii. 360, Leuwenhoek Pheasant, of Pennsylvania, account of, x. 450, . . . Edwards — description of a Chinese, xii. 202, Same Philippine Isles, ace. of the New, v. 442. Clain & Le Gobien Philips, Henry, plan for calculating tides, i. 239 Philips, Rich., agitation of the waters near Reading, x. 651 Philodemus, remarks on a piece of music of, found at Her- culaneum, x. 685, Watsoa — an epigram of, x. 686, Same Phlogiston, on the nature of, xv. 245, Kirwan — of the quantity of, in nitrous air, xv. 254, Sam© fixed air, xv. 255, Same -~ vitriolic air, xv. 260, Same ■ sulphur, xv. 26l, Same 1 marine acid air, xv. 262, . . Same ■ 1 metals, xv. 338, Same — affinity of metallic calces to, ibid, Same — experiments on, xvi. 420, 473, 518, 604, .... Priestley Phoca, account of the phoca barbata, viii. 658, — natural history of the genus phoca, x. l6l, Phoenician inscription, remarks on, xii. 115, — see Coins. Phcenicopterus, see Flamingo. Pholas conoides, description of, xii, 175, Parsons Phosphorus, accidental discov. of a sort of, ii. 368, Baldwin — of factitious shining substances, ii. 390 — of Kunckel, account of, ii. 489, Sturm — experiments on the solid and liquid, ii. 505, 518, . . Slare — experiments with, before the r. s., ii. 0'5'1, Same — Boyle's discovery of, iii. 478, and Note — to make minerals phosphorescent, iv. 317, • • Southwell — experiments on the mercurial, v. 254, Hauksbee — exper. on the phosphorus of urine, vii. 594, . . Frobenius vii. 596, Hanckewitz Parsons . . Same Swinton — fired by electricity, ix. 107, Miles — an easy method of making, xii. 579, Canton — of the colours emitted by, xiii. 130, Beccaria — see Light (phosphoric). Photometer, description of a, xvii. 359, Rumford Physeter macrocephalus, account of the, i. 46 Physic, see Medicine. Physiognomy, theory of, iii. 638, Guither Piazzi, Rev. Jos., result of various observations of the solar eclipse of June 1808, xvi. 529 Picard, John, biographical account of, i. 326, Note — observation of Saturn at Paris, i. 326 — measure of the earth's meridian, ii. 193 Pickering, Rev. Roger, on the seeds of mushrooms, viii. 71$ — culture of mushrooms, ix. 31 — plan and machines for a weather diary, ix. 34 — on manuring land with fossil shells, ix. 82 Pickersgill, Rich., track of a voyage to Labrador, xiv. 475 Picolo, Francis Maria, account of California, v. 458 Pictet, Mark Aug., convenience of the observatory of Geneva for measuring an arc of the meridian, &c, xvii. 34 Pigeons, a species from Hudson's Bay, xiii. 33S, .... Foster Pigott, Thomas, earthquake at Oxford, 1683, ii. 658 Pigott, Nathaniel, solar eclipse, 1765, at Caen, xii. 458 — observations of the transit of Venus, 1769, xiii. 49 — meteorological observations at Caen, xiii. 145 — astronomical observ. in the Netherlands, xiv. 22, 401 — discovery of some double stars, xv. 38 — astronomical observations in Glamorgan, xv. 117 — a meteor observed near York, August 1783, xv. 620 — transit of Mercuvy, May 1786, at Louvain, xvi. 135 Pigott, Edw., a nebula in Coma Berenices, xv. 37 — observations of the comet cf 1783, xv. 464, 621 — a new variable star, xv. 649 — transit of Mercury, 1 7 S6, at Louvain, xvi. 135 — latitude and longitude of York, xvi. 145 — observations of some luminous arches, xvi. 6*31 — lat. and long, of places near the Severn, xvi. 709 — variableness of two fixed stars, xviii. 1 02 l 2 84 PLA INDEX. PLI Pike , of glands in the stomach of a, iii. 7 1 / Musgrave Pile engine, theory of pile driving, xiv. 498, Bugge Pimenta, description of the tree, iii. 425, Sloane Pin, of a pin in a fowl's gizzard, v. 240, Regnart — found in the appendix coeci, viii. 89, Amyand — swallowed and discharged at the should., xii. 590, Lysons Pine apples, on the culture of, xir. 224, Bastard Pinelli, Mich., on the causes of gout, vii. 254 Pingre, Alex. Guy, biographical account of, xii. 117, Note — transit of Venus over the sun, 176l, xi. 595 — sun's parallax from the above transit, xii. 117 — transit of Venus, 17^9, West Indies, xiii. 81 Pintado, anatomy of the, iii. 392 Pitcairn, Robert, biographical account of, iv. 46, .... Note Pitch, oil &c, extracted from a sort of coal, lv.l6S, .... Ele — method of making near Marseilles, iv. 302, Bent — phosphoric nature of, v. 509, Hauksbee Pitkeathly, of the salt purging water at, xiii. 271, . . Monro Pitt, C.j m. D.,merc. injected into the jugulars of a dog, iv. 2/3 — on the motion of the stomach and guts, iv. 300 Pitt, Edmund, of the sorbus pyriformis [domestica] ii. 434 Pitt, Robt., M. u., of lumbago rheumatica convulsiva, iii. 621 Placenta, of a tumour in the human, xviii. 338, .... Clarke Plague, observs. and experts, on the pus of, ii. 491, Alprunus — at Dantzic, 1709, account of, vi. 23, Gottwald — on the quarantine necessary, ibid, Note — at Copenhagen, 17 1 1, vi. 75, Chamberlayne — at Constantinople, vi. 450, Timoni — inoculation with syphilis noprotection against, vi. 452, Note — observations on bodies dead of, vi. 559, Deidier — causes of pestilential diseases, ix. 4, Seehl — at Constantinople, letters concerning, x. 239, 242, 2S3 ; general remarks, xii. 102, Mackenzie — answer to a query respecting, x. 580, Parsons — at Aleppo, 1758, &c, some account of, xi. 686, . . Dawes — times of its appearance and disappearance at Constan- tinople, in the years 1748 to 1761, xii. 108, Mackenzie Plane, a clock ascending on an inclined, ii. 439, De Gennes — ascent of orange-oil between glass planes, v. 659, 679> Hauksbee — of spirit of wine between glass planes, vi. 40, 41, Same — of water between glass planes, vi. 40, Same Planets, on Cassini*s method of finding their apogees, eccen- tricities, and anomalies, i. 424, Mercator — discovery of 2 new ones about Saturn, ii. 50, . . Cassini — aphelia, eccentricities, &c. of, ii. 326, Halley — theory of their motion, v. 12, Gregory — on Cassini's orbit of, v. 152, Same — solution of Kepler's prob. on the motion of, vi. 1, Keill . — to find the places of, by the stars, vi. 530, Halley — inquiry into the figure of, viii. 207, Clairaut — contraction of the orbits of, x. 16, Euler — of the irregularities in the motions of, xi. 579, Walmesley — observations of their rotation, xv. 50, Herschel — see particular Planets in their Places. Planks, to bend by a sand-heat, vi. 577, Cay Planman, transit of Venus, 176l, xi. 56*5 — parallax of the sun by a new method, xii. 521 Plant, Rev.M., earthquakes in New Eng., 1727-41, viii. 552 Planta, Jos., account of the Romansh language, xiv. 7 Plants, observations on the roots of, i. 317, Tonge — healing quality of the asphodil, ii. 228, .... Mackenzie — catalogue of plants at Tangier, iv. 85, Spottswood — from Maryland, a catalogue of, iv. 326, Petiver — of several in Jamaica, iv. 362, Sloane — »f the East Indies, presented to the r. s., iv. 501 — to discover the virtues of, by the tastes, iv. 676,. . Floyer — of water- weeds, and auimalcula on, v. 6, 52, Leuwenhoek Plants, on the same subject, v. 74 — seminal use of the flower of, v. 68, Morland — of animalcula on duck-weed, v. 175, .... Leuwenhoek — growing in Cornwall, v. 702, Lhuyd — description of the genus araliastrum, vi. 314, . . Sberrard — discovery of their virtues by the structure, vi. 459, Blair — observations of the generation of, vi. 534, Same — of the musa family, vii. 422, Same — impregnation of the seeds of, viii. 57, Logan — botanical description of several, viii. 358, .... Moehring — a perfect plant discovered in the seed, viii. 429, . . Baker — Haller's methodus plantarum, viii. 657, — letter on the sex of, x. 1 76, Mylius — observations on the sex of, x. 177, Watson — unnoticed in Ray's synopsis, x. 250, Same — remarks on the sleep of, x. 197, Pulteney — enumeration of plants that sleep, x. 198 — description of the nolana prostrata, xi. 708, Ehret — microscopical observations of the sexes of, xii. 248, Stiles — a rare plant of the isle of Skye, xii. 642, Hope — of plants indigenous in England, xiii. 171, ... . Waring — of the brownaea genus described, xiii. 419, Bergius — on the fructification of submersed plants, xviii. 68, Serra — see Trees, Vegetables. — see also, Acmella, Alga, Aloe, Amomum, Aphvllon, Arachidna, Araliastrum, Arbutus, Averrhoa, Benjamin- tree, Bidetis, Box, Bread-fruit tree, Broxcmca, Byssus, Cabbage-bark tree, Cacao-tree, Centaurea, Cereus, Chlo- ranthus, Cinnamon, Coffee-tree, Cinchona }Croton,Cy anus, Cyprus, Dentaria, Dittany, Bog Mercury, Elder, Faba St. Ignatii, Fern, Gardenia, Ginseng, Halesia, Hemlock, Henbane, Holly, Hypnum, Indigo-pLmt, Iris, Jasmint, Lauro-cerasus, Lily, Mackenboy, Maize, Mallow, Man- grove, Manchenille, Mamiracum, Mango, Mangostan , Monkshood, Moxa, Mulberry, Musa, Mushroom, Ka- pellus, Nolana, Ni;ctanthes, Oak, CEnanthe crocata, Ophrys, Opuntia, Osteocolla, Oxyoides, Pareira brava, Pimenta, Protea argentea, Rheum palmatum, Rhus, Sal- vadora, Soap-tree, Sorbus, Sphondylium, Spikenard, Starry -anniseed, Sugar-cane, Sun-plant, Tobacco, Toxi- codendron, Willow. Plants from Sir Hans Sloane's garden, presented to the r. s., by the apothecary's company, v. 659, 667; vi. 17, 155, 168, 198, 637; vii. 27, 85, 155, 191, 321, 377, 442, 513, 577, 631 ; viii. 1, 54, 113, l60, 2/8, 385, 424, 725, ; ix. 30, S2, 128, 251, 370, 635 ; x. 7, 18, 29, 176, 242, 34), 456, 579, 706; xi. 124, 246, 338, 473, 530,6*15,685; xii. 115,203, 347, 478, 56*1, 667; xiii. 91, 173, 370, 530 Plants (Chemistry) remarks on the alkalizate of, ii. 124, 158, 16*6, Coxe Platina, account of, on its first discovery, x. 98, Brownrigg — specific gravity of, x. 98, 499, Note — notice of Dr. Lewis's experiments on, x. 103, .... Note — analytical and chemical experts, on, x.495, xi. 97, Lewis — chemical experiments on, xiv. 40, Ingenhousz — of the action of nitre on, xviii. 139, • • • • Tennant Piatt, Joshua, a curious spheroidal stone, x. 77 — fossil thigh-bone of a large animal, xi. 204 — origin and formation of belemnites, xii. 9' Piatt, Thos., experiments on the poison of vipers, ii. 8 Plaxton, Rev. George, of the parishes Kinnardy and Do- nington, v. 357 Playfair, Rev. John, arithm. of impossible quant, xiv. 356 Pleurisy, an infectious and periodical, iii. 1 19, .... Bonnet Plica Polonica, case of, and the cause, vii. 462, .... Vater — further account of, vii. 572, Klein — account of the woman having the, ix. 356, Ames POL INDEX. POR 85 Pliny, remarks on a passage in, ix. 303, Folkes Plott, Robt., ll. D., biographical account of, ii. 394, Note — formation of salt and sand from brine, ii 589 — on the sepulchral lamps of the ancients, iii. 100 — account of a meteorological register, iii. 139 — history of the use of incombustible cloth, iii. 179 •— proper time for felling timber, iii. 422 — nature of the mineral called black lead, iv. 272 — catalogue of electrical bodies, iv. 323 Pluche, Abbe, cause of the smut of corn, viii. 408 Plukenet, Leonard, biograph. account of, iii- 458, ..Note Plum-stone, lodged for 30 years in the bowels, iv. 7l5,Yonge — disorder from swallowing, v. 552, Holbrooke — mischiefs arising from swallowing, vi. 253, .... Derham Pneumatics, shooting by rarefaction of air, iii. 273, Papin — see Air-pump. Pococke, Rev. Rich., biograph. account of, ix. 457, . . Note — of the giant's causeway in Ireland, ibid, & x. 382 Points, mathematical, porportion of, v. 678, Robartes Poison, a poisonous substance arising on a lake, i. 721 — on several sorts, particularly viper's, iii. 653,. . . . Mayerne — effects of a poisonous root, iv. 183, Ray — from the euwane tree, v. 281, Leuwenhoek — effects of various, on animals, v. 684', Courten — poison-wood tree of New England, vi. 507, . . Dudley — vi. 508, Sherrard — antidote to the West Indian, viii. 542, Milward — experts, with the Indian poison, ix. 3l6, .. Brocklesby — a poisonous root mixed with gentian, ix. 488, .... Same — of the ticunas and lamas, experts, on, x. 144, . . Herissant — result of experts, on the same poison, ibid, .... Fontana — poisonous effects of an effervescent mixt. xi. 66, Mounsey — water and oil recommended as a remedy for poison taken internally, xi. 477, Note ; 479, Willis — experts, on the ticunas poison, xiv. 641, Fontana , poisonof the lauro cerasus, xiv. 66l, Same Poleni, John, solar eclipse, Padua, Sept. 1726, vii. l6*2 . lunar eclipse, Oct. 1726, ibid Feb. 1729, vii. 364 July 1729, vii. 364 solar eclipse, Sept.1727, vii. 248 ■ July 1730, vii. 427 — meteorol. observs. at Padua, 1725 — 1730, vii. 510 ■ for 1731 — 1736, viii. 196 meteoric lights observed Dec. 1737, viii. 458 — on pendulums affected by a centrifugal force viii. 627 Pol hill, Nathaniel, remarks on bees, xiv. 304 Poland, of the sal-gem mines in, i. 469 Polarity, see Magnet, Magnetism. Pole (of the earth) elevation unaltered, iii. 407, Wurtzelbaur — see Mei idian . Polygamy, its effect on population, x. 5S2, Parsons Polygon, theorem on thr, xii. 223, Waring — theorems for the solution of, xiii. 647, Lexel — polygons in and about circles, xiii. 653, Horsley Polypodium, observ. on the seecis of, v. 197, Leuwenhoek Polypus (disease) in the heart, body dissected, iii. 21, Gould — in the nose, origin discovered, iv. 152, Giles — in the lungs, iv. 488, Bussiere — found in a dog, iv. 525, Musgrave — in the vena pulmonalis, iv. 563, Cowper — coughed up from the wind-pipe, vii. 188, Samber the lungs, vii. 481, Nicholls — from the hearts of sailors, viii. 580, Huxham — at the heart, ix. 274, Templeman Polypus (animal), account of, viii. 607, Gronovius — > on its living after being mutilated, viii. 6ll — papers read before c.s. respecting, viii. 623,. . Mortimer Polypus (animal) of fresh water, observs. and experts, onj ibid, Tremble} — experiments on, viii. 676, Folkes — observations on, viii. 6*85, Duke of Richmond — observations on a dried, viii. 724, Baker — newly discovered species of, ix. 75, Trembley — observations of several sorts of, ix. 377, Same — of coral, account of, x. 154, Donati — cluster-polype of salt water, [vorticella encrinus] x. 409, Ellis — description of some polypi, x. 617, Brady — remarks on the polypi of coral, xi. 83, Trembley — description of the American cuttle fish, xi. 286,. . Baker — different sorts of the actinia, xi. 525, Gaertner Pompey's pillar, on the real date of, xii. 473, .... Montagu Ponds, that ebb and flow, cause of, vii. 39, . . Desaguliers Pond, Arthur, a stone with the impression of a fish, x. 628 Ponza, some account of the island of, xvi. 133, . . Hamilton Pooley, Giles, digging and preparing of calamine, iii. 515 Pope, Walter, m. d., on the mines of mercury in Friuli, i. 10 — the production of wind by the fall of water, ibid Poppy, strange effects of the chelidonium glaucium, iv. 295, Newton Population, houses and hearths in Dublin, 1696 and 1697, iv. 481, South — sea-faring men in Ireland, 1697, ibid, Same — number of people in Ireland, 1696, iv. 482, Same - of Romish clergy in Ireland, 1698, ibid,. . Same of the parishes Kinardsey and Donington, v. 357, Plaxton propor. births of males and females, v. 606, . . Arbuthnot of Stoke-Damerell, 1733, viii. 53, ... . Barlow — of Holland, West Friezland, Haarlem, &c, viii. 253, Eames viii. 628, Kersseboom — of Bristol, 1741-50, x. 378, Browning — within the London bills of mortality, 1704-53, x. 535, Braikenridge — of Constantinople, x. 580, Parsons — of England, method of enumerating, x. 621, Braikenridge — Britain and Ireland, rate of increase of, xi. 51, . . Same — of England, methods of estimating, xi. 1 86, .... Forster ■ xi. 188, Braikenridge — increase of, at Madeira, xii. 475, Heberden in Anglesea, xiii. 422, Panton — of Manchester and its neighbourhood, xiii. 659, Percival — table of the proportion of males to females, xiii. 632, Price — of Chester, 1774, xiv. 311, Haygarth — of London, number of natives compared with those born in the counties of Britain and Ireland, xv. 122, Bland — comparison of the number of males and females born, xv. 121, Note, Same — see mortality (bills of) , London}Paris,Constantinople, and Bristol. Porcupine, its anatomy compared with a hedge-hog, iii. 39 1 — swallowed by a snake, and causing its death, ix. 102, Wollaston — of the hystrix dorsata from Hudson's Bay, xiii. 328, Forster Pores in the skin of the hands and feet, use of, iii. 35, Grew — on the porosity of bodies, iii. 72, Boyle Porpoise, dissection of i. 639. Ray — anatomical description of, ii. 500, Borelli — venom in the tooth of, iv. 21 1, Lister Porter, Sir J., answers to queries, by Dr. Maty, relative to Constantinople, x. 580, 6l8 — earthquakes at Constantinople, x. 586 — astronomical, &c. observations in Asia, x. 6l8 — transit of Venus over the sun, 1761, xi. 56& 86 PRI INDEX. PUR Note Note Portland, Isle of, damage done in 1696, iv. 198, Southwell Potash, preparation and uses of, ix. 572, Mitchell Pott, Percival, biographical account of, viii. 46*4, .... Note — of tumours which rendered the bones soft, ibid — on a hernia of the urinary bladder, xii. 100 Potter, Rev. John, biographical account of, iv. l6l, . Pouhon water, see Waters, (mineral and medicinal) Pound, Rev. Jas., astronomical observ.,vi. 212, 264 — motion of the satellites of Saturn, vi. 349 — lunar eclipse, August 1718, at Wansted, vi. 373 — transit of Jupiter's 4th sat. over his disk, vi. 386 — tables for eclipses of Jupiter's 1st satellites, vi. 426 — astronomical observations, vi. 442 — observations with Hadley's telescope, vi. 664 Poupart, Francis, biographical account of, iv. 209, . . — anatomy of the leech, ibid — description of the libella, iv. 519 — effects of a dreadful scurvy at Paris, l699> *• 454 Povey, Thos., transmutation of copper into brass, iii. 535 Powder, of a sort for improving cast metal, ii. 68 Powell, John, case of hair voided with the urine, viii. 489 Powle, Henry, iron works in the forest of Dean, ii. 418 Precipitations (Chemistry) of metals, by each other, from vitriolic acid, xv. 341, Kirwan Pregnancy, case of a seeming, but false, iii. 176,. . . . Cole — force of imagination in, iii. 375, Ash — cure of a fractured arm, retarded by, x. 28, .... Barde Preservation of bodies, see Putrefaction. Piessure, of weights on moving machines, x. 558, . . . Hee — see Water, Gravity, &c. Prestet, John, biographical account of, ii. 307, Note Preston, Charles, m. d., of a stone inside the bladder ad- hering to one on the outside, iv. 109 — dissect, of a dropsical patient ; causes of dropsy, iv. 114 — dissection of a boy who died suddenly, iv. 122 — of the interior structure of fish, iv. 138 — of a child born alive without a brain, iv. 149 Preston, Thomas, account of the Island Shetland, ix. 44 Prevost, P., reflexibility of the rays of light, xviii. 320 Price, Charles, on the stomachs of oxen, vii. 264 Price, Richard, d. d., biograph. account of, xii. 160, Note — on the expectations of lives, &c. xii. 6ll — on the values of reversions, xiii. 50 — effect of the aberration of light in observing a transit of Venus, xiii. 89 — insalubrity of marshy situations, xiii. 505 — different duration of life in towns and villages, xiii. 679 — differ, value of annuities, payable at differ, periods, xiv. 5 — the mortality of males greater than of females, xvi. 122 Prickle-back (fish) observations on, ix. 322, Arderon Priestley, Joseph, ll. d., biog. account of, xii. 510, Note — prismatic colours caused by electrical explosions, ibid — lateral force of electric explosions, xii. 600 — general experiments on electric explosions, xii. 603 — investigation of the lateral electric explosion, xiii. 36 — experiments on charcoal, xiii. 45 — observations on different kinds of air, xiii. 313, 666 — account of Mr. Henley's electrometer, xiii. 323 — noxiousness of the effluvia of putrid marshes, xiii — on respiration and the use of blood, xiv. 34 — an experiment relating to phlogiston, xv. 453 — experiments and observations on air and water, xv. — on the composition of water, the principle of acidity ; and on phlogiston, xvi. 419, 473, 518 — phlogistication of spirit of nitre, xvi. 557 — transmis. of vapour of acids through hot tubes, xvi. 602 — experiments on phlogiston, xvi. 604 502 703 Priestley, Jossph, ll. p., on the air of respiration, xvi. 647 — decomp. of dephlogisticated and inflammable air, xvii. 55 Prince, Rev-, unusual agitation of the sea, 1756, xi. 1 Pringle, Sir John, >i. v., biographical account of, x. 57. xiv. 284, Note — of substances resisting putrefaction, ibid, 73 — further expers., and on promoting putrefaction, x. 84 — of the jail fever in Newgate, x. 318 — case of the flexibility and dissolution of bones, x. 406 — agitation of the waters atTunbridge, 1755, x. 649 — earthquakes at Brussels 1755-6y x. 695 — agitat. of the waters in Scotland and Hamburgh, x. 697 — efficacy of soap and lime-water in the stone, xi. 115. 122 soap in the stone, x. 122 — a fiery meteor seen in various parts of Britain, Nov. 1758, xi. 377 — remarks on the above observations, xi. 388 Printing, when and by whom invented, v. 50, Ellis — account of the invention of, and anecdotes, v. 80 — essay on the invention of, v. 350, . . Bagford — in imitation of painting, of Le Blon's method, vii. 477, Mortimer — first permission of, at Constantinople, vii. 556, . . Eames — approach of the Romans to the art of viii. 248, Mortimer — discouragement of, at Constantinople, x. 583,. . Parsons Problems, solution of three astronomic, xiii. 348,Pemberton Proby, Thos., extraction of an ivory bodkin from the blad- der, iv. 46'8 Projectiles, problems on the motion of, iii. 265,. . . . Halley — on the parabolic motion of, vi. 510, Taylor — their motion near the earth's surface, ix. 464, Simpson Propagation, effect of extirpating one ovarium on the power of, xvi. 2.36, Hunter Proportion, laws of proportional magnitudes, xiv. 183,Glenie Protea argentea, (silver pine) account of, iii. 513, .. Sloane Prussian blue, see Blue. Ptarmigan, on the nat. history of the, xiii. 433, Barrington Ptolemy, Claudius, biograph. account of, ii. 559, .... Note Pryme, Abm. de la, Roman antiquities in Lincoln., iv. 494 — fossil shells and fishes, iv. 521 — of subterraneous trees and the cause, iv. 624, 645 — experiments on vegetation, iv. 6'97 — a water spout seen in Yorkshire, iv. 7^9 at Hatfield, v. 17 Pudenda, see Generation Pulex, see Flea. Pullein, Rev. Sam., an improved silk reel, xi. 324 — a species of silk- pod from America, xi. 332 Pulleyn, Octavian, inscriptions on an urn, iv. l65 Pulleys, experiments of the friction of, vii. 066, Desaguliers — new combination of, x. 278, Smeaton Pulmonary vein, animals that have lungs without, ii. 69 — structure of, and a polypus in, iv. 563, Cowper Pulse, on the variety and motion of iii. 169, • • Abercromby Pulteney, Rich., m. d., biograph. account of, xi. 45, Note — of his catalogue of Leicestershire plants, ibid, ..Watson — on the night-shade [atropa belladonna] xi. 85 — on the sleep of plants, xi. 197 — case of an enlarged heart, and observations, xi. 585 — medicinal effects of the cenanthe crocata, xiii. 357 — births, deaths, at Blandford Forum for 40 year<, xiv. 395- Pumice stone, micros, obsei vs., on, v. 266,. . Leuwenhoek — large shoal of at sea, vii. 234, Dove Pump, a cheap and useful one, ii 396, Coniers — account of the Hessian, ii. 154, Papin Punic, see Coins, Inscriptions. Purcell, J., m. d., a doable uterus and vagina, xiii, 572 QUI INDEX. RAT *r Purging medicines, on the principles of, iv. 6*52, .... Bolduc — adapted to ages and constitutions, v. 250, 399, Cockburn Purple fish, on the buccinum lapillus, iii. 252, Cole — of a species of aplysia, xi. 225, Peyssonel Putrefaction, preservation from, of a body in a copper-mine, vii.41, Leyel — experts, on substances resisting, x. 57, 73, • . • • Pringle -— further experts., and on promoting it, x. 84, Same — lime-water a preservative from, x. 358, Hume — experts, on the nature and causes of, xiii. l63,. . . . Crell Pye, Wm., account of the island Manilla, x. 6'73 Pyke, Isaac, method of making mortar at Madras, vii. 515 Pylarini, Jas., M. d., biograph. account of, vi. 207, . . Note — practice of inoculation in Turkey, ibid Pyrites, the cause of earthquakes and lightning, iii l6,Lister Pyrmont, a sulphureous cavern at, viii. 204, Seip Pyrmont waters, nature and virtues of, vi. 2S0, .... Slare — difference of, and the Spa, vi. 281, Note — stones voided by drinking, vi. 6o6", Vater Pyrometer, with table of expansion, x. 482, Smeaton — see Expansion. Pyrometry, essay on, xiv. 387, De Luc Pyrorganon, see Electricity. Q Quab, description of the fish so called, ix. 470, Baker Quadrant, for altitudes without a horrizon, vii. 531, Elton — on Godfrey's improvement of Davis's, vii. 6*69, . . Logan — a new mural, ix. 347, Gersten — usefulness of Hadley's for pilotage, xii. 1.97, . . Mitchell — additions to Hadley's, more useful at sea, xiii. 291 — method of using Hadley's quadrant, xiii. 292, Maskelyne — a new division of the, xv. 464 Quadratrix, construction of, to the circle, iv. 462 . . Hutton — to the hyperbola, v. 302, Perks Quadrature, of figures geometrically irrational, iv. 202, Craig — of the logarithmic curve, iv. 318, Same — of the lunula, iv. 452, Wallis, &c. — of some sorts of curves, iv. 658, Demoivre — of figures, method of determining, v. 24, Craig — of a curve of the third order, vi. 183, Demoivre — see Curves. Quadrature of the circle, see Circle. Quadrupeds, see Antelope, Armadillo,, Bear, Camel, Camelo- pardalis, Caracal, Chamois, Civet-cat, Coati-tnundi, Cow, Deer, Dog, Dromedary, Elephant, Elk, Ermine, Fox, Gazelle, Hare, Hedgehog, Hind (Sardinian,) Home, Jackal, Kanguroo, Lyon, Lynx, Marten, Mice, Monkey, Moose-deer, Musk-hog, Nyl-ghaw, Opossum, Orang Outang, Ornithorhyncus, Otter, Porcupine, Rabbit, Rat, Rhinoceros, Shrew, Spiirrel, Stag, Sus QZthiopicus, Tyger-cat, IVeesel. Quantity, the sev. species of infinite quantity, iii. 465, Halley — essay on, ix. 559, Reid — finding the values of algebraic quant, xvi. 191, Waring — elements of exponential quant. &c. xvii. 703, L'Huillier Quarantine, as performed in England, remarks on, x. 239, Mackenzie Quarries, remark, stone quarry at Maestricht, i. 552 ; v. 51 — see Marble. Quassia root, efficacy of, in fevers, xii. 515, Monro ■ xii. 5l6, Farley Quereus coccifera, account of, i 134, Note Quec, A. do, method of rowing men of war in a calm, vi.5-15 Quicksilver, see Mercury (mineral) Quinarius, sec Coins. Quincy, John, m. d., on the operation of medicines, vi.479 Quintiny, John de la, cultivation of melons, i. 327, 335 R Rabbit, specific characters which distinguish it from the hare, xvi. 267, Barrington Radicals, reduction of, to simpler terms, viii. 271, Demoivre Rain, diminished in the West Indies by clearing away the trees, i. 175 ; remarks on the rains in the W.Indies, ibid — quantity falling sufficient to supply rivers, ii. 542, Papin — contrivance for measuring the quantity of, ibid,. . . . Note — method of estimating the fall of, iii. 619, .... Townley — of a storm of salt rain, v. 91. Fuller — of the same storm, & the weather preceding, v. 92,Derham — of the same salt storm, v. 93, Leuwenhoek — a violent storm of, at Denbigh, v. 331 — effects of a violent shower in Yorkshire, vi. 585, Thoresby — instrument for measuring the depth of, vi. 658, Horsley — difference of the fall at different heights, xii. 659, Heberden ; xiii. 419, Note — a remarkable kind which fell at iEtna, xv. 165, Gioeni — see Meteorological Observations, [Feather, Storms. Rainbow, of two crossing each other, seen at Chartres, i. 73 — optical observations on the, ii. 222, Linus — an extraordinary, seen at Chester, iv. 277, .... Halley — on the diameter and colours of, iv. 527, Same — description of a lunar iris, v. 642, Thoresby — observations of an inverted, vi. 532, Whiston — seen on the ground, vi. 541, Langwith — account of a secondary or reflected, vi. 623, .... Same ■ vi. 624, Pemberton — and vapours accounted for, vii. 323, Desaguliers — an unusual one, seen July, 1748, ix. 682, Daval — an inverted rainbow on the grass, x. 200, Webb — of a solar iris seen after sun-set, xi. 137, .... Edwards — account of several lunar rainbows, xv. 353, . . Tunstall — account of 2 primary rainbows, xvii. 282, Sturges Rain-gage, or ombrometer description of, ix. 36, Pickering — plan of his cistern for rain, xiii. 131 Barker — description of that used by the r. s. xiv. 52, Cavendish Ramazzini, Bernardin, biograph. account of, iv. 213, Note — distemper among the cattle in Italy, vi. 78 Ramsden, John, descrip. of two new micrometers, xiv. 557 — new eye-glasses for telescopes, xv. 350 Rana piscatrix, see Frog-Jish. Ranby, John, biographical notice of, vii. 12, Note — dissection of an eye with cataract, vii. 12 — dissection of an ostrich, vii. 69 — of a duct from the glandula renalis, vii. 84, 163 — dissection of part of a rattlesnake, vii. 217 — observations in dissecting several human bodies, vii. 226 an ostrich, vii. 392 — of a large umbilical rupture, vii. 513 Raper, Matthew, on the measure of the Roman foot, xi. 485 — on Norwood's measure, of a deg. on the meridian, xi.593 — observation of a solar and lunar eclipse, 1764, xii. 116 — value of ancient Greek and Roman money, xiii. 193 Raspe, R. E., on the fossil bonesof large quadrupeds, xii, 6l2 — opinion of the origin of white marble, xiii. 10 — ■ of some Basalt hills in Hessia, xiii. 222 Rastell, T., m.d., Droitwich salt springs & manufac, ii. 463 Rastrick, W., observ. of aurorae boreales for 4 years, vii. 185 Rat, microsc. observ, on the testicles of, iii. 481, Leuwenhoek — dissection of a, iii. 482 Rathbone-place water, analyt. exper. on, xii. 393, Cavendish Rattle-snakes, killed by wild penny-royal, i. 16, ... . Taylor — polygala senega, an antidote for the poison of,i. 16, Note — dissection of a, ii. :j61, Tyson — description of, vi. 642, : Dudley — experiments on the poison of vii. 196 Hall 58 I VO INDEX. JOI Intromsception, dissection of an extraor., xvi. 119, Lettsom Inundatiou, an extraor., in the Mauritius, iv. 297, Witsen — account of two in Ireland, v. 485, Derham — an extraordinary, in Cumberland, x. 18, Lock Ipecacuanha, on the use of for loosenesses, iv. 237 — remarks on the above, iv. 239. Sloane — of the different sorts of, vii. 356, Douglas — observations on, ix. 126, Gmelin — asthma caused by the effluvia of, xiv. 18, Scott Ippolito, Count, earthquake in Calabria, 1783, xv. 383 Ireland, of the bogs and loughs in, iii. 142, King — immense horns found, and other natural curiosities, iv. 156, Molyneux — formerly more populous, v. 406, . . Archbp. of Dublin — of the natural hist, and antiquities of, v. 694, 700, Lhwyd — strata and volcanic appear, in the north of, xvi. 639, Mills — see Population, Bogs, Giant's Causeway. Iris (nat. hist.) of an oddly figured iris, ii. 180, . . . .Lister Iris (meteorology) see Rainbow. Iron, effect on, by the air of the sea, i. 173 — found in common brick earth, i. 622 — experiments on the polarity of, iii. 674 — to give a copper colour to, iv. 303, Southwell — of an ideot who swallowed, v. 433, Amyand — increase of polarity by remaining long in one place, vi. 576, Leuwenhoek — of the mines in Cornwall, vii. 248, Nicholls — to give magn. virt. to, without a loadstone, vii. 540, Marcel — the melting of, with pit-coal, ix. 305, Mason — a mountain of, at Taberg in Sweden, x. 564, . . Ascanius — observations on sand- iron, xi. 689, Home -— solubility of, by fixed air, xii. 633, Lane — a specimen of native, from Siberia, xiii. 569, • • • • Stehlin — remarks on the iron-ore of Siberia, xiv. 99, Pallas — a mass of native, found in S. America, xvi. 369, ■ • Celis — appearances on the conversion of cast into malleable, xvii. 47, 209, Beddoes — polarity of iron-filings, xvii. 145, Bennet — experiments on the nature of wootz, xvii. 580 . . Pearson — properties of iron in its different states, xvii. 588, . . Same — see Steel. Iron works, in the forest of Dean, ii. 418, Powle — in Lancashire, iii. 523 Sturdy Irritability of animal fibres, experts, on, x. 6l3, Brocklesby Irreducible case, see Cordon. Ironside, Lieut. Col. culture and uses of the sun-plant of Hindostan, xiii. 505 — manufacture of paper from the sun-plant, xiii. 506 Ischia, the volcanic origin of, xii. 593, Hamilton Isinglass, method of manufacturing, xiii. 36*1, . . . .Jackson Island, a new raised, in the Archipelago, v. 407, • • • • Sherard — a new volcanic, near Santorini, v. 446,. . . . Bourgignon — of the same, and phenomena attending it, v. 6*47, Goree — sunk, recovered from the sea, vi. 423, . . Chamberlayne — a new volcanic, near Tercera, vi. 584, Forster — on the formation of islands, xii. 454, Dairymple Isle, Jos. N. de, see Dclisle. Isnard, Mons., management of silk-worms, i. 30 Isoperimetrical probl., resolution of, x. 560, xi. 238, Simpson Isthmus, remarks on the probable existence, formerly, of one between Calais and Dover, iv. 6l 8, 637, Wallis — inquiry on the same subject, vi. 293, Musgrave Istria, observations in a tour through, ii. 284 Vemon Italy, state of learning in, iv. 506, Silvestre — remarks on a tour through, x. 52, More Itch, of the animalcula which produce it, v. 1, , Mead Ivory, microscopical observations on, ii. 438, . . Leuwenhoek Jackal, similarity, in species, to the wolf and dog, xvi. 562, Hunter Jackman, Rev. J., on the rule for finding Easter, v. 250 Jackson, Humphrey, biog. account of, xiii. 362, . . Note — method of making isinglass, ibid Jackson, Wm., m. d., way of making salt, and description of the springs at Nantwich, i. 397, 405 Jacob, Mr., elephant's bones in the Isle of Shepey, x. 489 Jaculator Fish, [chaetodon rostratus] desc, xii. 110,Schlosser account of, xii. 321, Hommel Jamaica, of the alligators at j tortoises ; chegoes ; shining flies ; manchenille apple, &c. i. 295, Norwood — of a hot mineral spring at, iv. 79 Beeston — of several plants of, iv. 362, Sloane — observations on natural history of, vi. 368, .... Barham — longitude of Port-Royal, vi. 619, Halley — temperature of springs and wells at, xvi. 377,. . Hunter James, Rob., m. d., biographical account of, viii. 69, Note — experiments with mercury for cure of mad dogs, ibid Jamineau, Isaac, eruption of Vesuvius, 1754, x. 563 James's powder, analytical exper. on, xvii. 87,. . . . Pearson Japan, natural history, arts, manners, &c. of, i. 365 — method of curing several diseases, ii. 633 — journal of a residence at, xiv. 634, Thunberg Japan-varnish, manufacture and use of, iv. 299 Jardine, Lieut., transit of Venus and solar eclipse, 1769, Gibraltar, xii. 657 Jartoux, Father, description and virtues of ginseng, vi. 56 Jasper, result of an experiment of melting, i. 620,. . Becher Java, sexual intercourse at an early age at, iv. 298 Jaundice, case of, which afFected the vision, iii. 652, Briggs — by a stone obstructing the bil. duct, v. 292, . . Musgrave — communicated in coitu, ix. 686, Cooke Jaw, loss of part of the bone supplied by a callus, viii. 326, Sherman — locked jaw after a slight contusion, xii 201,Woolcombe — locked jaw cured by electricity, xii. 391, Spry Jeake, Samuel, elements of shorthand, ix. 5l6 Jeaurat, Mr., descrip. of an iconantidiptic telescope, xiv. 501 Jenkins, Hen., aged 169 years, account of, iv. 92, Robinson — on the great age of, iv. 167, Hill Jenkins, Samuel, machine for grinding lenses, viii. 451 Jenner, Edward, m. d , nat. hist, of the cuckoo, xvi. 432 Jenty, Nich., case of the cohesion of the intestines, xi. 215 Jernegan, Charles, m.d., cystis of water in the liver, ix. 108 Jessamine, change of colour in the blossom of, vi. 489, Cane Jessop, Mr., different sorts of damps, ii. 224 — extraordinary worms voided at the mouth, ii. 225 — remarks on fairy circles, ibid — on damps of mines, ii. 244 Jessop's Well, virtues of the water, x. 48, ........ Hales Jesuits, succesion of earthquakes at Brigue, x. 707 — solar eclipse, 1764, at Rome, xii. 150 Johannes, F., medicin. virtues of the ignatia amara, iv. 356 Johnson, Mau., earthquake at Scarborough, 1737, viii. 514 — a new metalline thermometer, ix. 459 Johnson, Sir Wm., of the languages, manners, &c. of the North American Indians, xiii. 407 Johnston, — , m. d., of gold colour, stones in the blad. ii. 125 Johnstone, James, m. d., biog. account of, xi. 211,. . Note — two extraordinary cases of gall-stones, ibid — on the use of the ganglions of the nerves, xii. 123, xiii. 8 — of a foetus with an imperfect brain, xii. 404 Johnstone, , m. d., of the earthquake of 1795 as felt at Worcester, xviii. 31 Jointed worm, see Lumbricus latus. JUP INDEX. KER 59 Joints, of a man' who had the power of dislocating, and replacing them at pleasure, iv. 294 Jones, Rev. Hugh, account of Maryland, iv. 46 1 Jones, Jezreel, food of the moors of Barbary, iv. 407 Jones, Thomas, a high tide in the Thames, 1726, vii. 133; 1736, viii. 59 Jones, William, biographical account of, ix. 357,. . . . Note : — equations of goniometrical lines, ibid — ■ construction of logarithms, xiii. 190 — efFects of lightning on Tottenham-court chapel, xiii. 307 — on the conic sections, xiii. 458 Jones, Sir Wm., catalogue of Sanscrita mss., xviii. 427 Oriental mss., xviii. 563 Journal, of a voyage to the East Indies, method of, xiv. 386, Dalrymple Journeys, see Voyages. Judda, observations on a voyage to, xiii. 287, Newland Jugulars, mercury injected into the, iv. 273,. . . . Musgrave Juices, of plants, on the nature and differ, of, iv. 123, Lister — see Sap. Julian Period, M. de Billy's method of finding, i. 121 ; demonstrated by Mr. John Collins, i. 207 Jupiter, observation of a spot in one of the belts of, i. 3 — discovery of the spot claimed by Divini, i. 68 — one of the satellites passing over it, i. 52 — of a permanent spot, showing that this planet moves round its own axis, i. 52 — rotation of, on its own axis, i. 60, .... Hook and Cassini — observation of, i. 83, Hook — observations of the spots in, and cause, i. 706, Cassini; calculation of the rotation, ibid. — inclination of, to the ecliptic, ii. 65, Flamsteed — occulted by the moon, June, 1679, "• 480, . . . Hevelius — . ii. 481, Cassini — observ. of conjunctions with Saturn, ii. 637,. . Flamsteed — 3 conjunctions with Saturn, 1682-3, ii. 66*2, . . Hevelius — two eclipses of, by the moon, 1686, iii. 294, Hook, &c. — eclipsed by die moon, 1686, Dantzic, iii. 33 1 , Hevelius . iii. 326, Flamsteed — occultation by the moon, 1715, vi. 212, Pound — occultation of a star in Gemini by, vi. 271 — and his satellites occulted by the moon, viii. 477, Bevis — occultation by the moon, London, 1744, ix. 45, ... Same — conjunction with Venus, Pekin, 1748, x. 22, Hallerstein Jupiter's satellites, Auzout's opinion respecting, i. 25 - — one of the satellites passing over the planet, i. 41 — occultation of the first satellite, i. 658, Hevelius — configuration of, and predictions, ii. 324, Cassini — eclipses and ingresses of, 1683, ii. 660, Flamsteed — calculation of eclipses for 1684, ii. 679> Same — calculations of eclipses verified, iii. 234, Same instrum. to find the dist. of, from his axis, iii. 246, Same — calculation of eclipses of the first satellite, iii. 672 — emer. of the first from Jupiter's shadow, vi. 92, Bianchini — transit of the fourth over Jupiter's disk, vi. 386,. . Pound — observations with reflecting telescopes, vi. 665, . . Hadley — eclipse of the first satellite at New York, vii. 49, Burnet Lisbon, vii. 55, . . Carbone — immersions and emersions observed, vii. 132, Lynn — eclipses of the first satellite, at Lisbon, vii. 141, Bradley — i vii. 143, Carbone • — _____ Toulon, vii. .144, . .. Laval — eclipses observed at Rome, vii. 165, Bianchini ■■ Bologna, vii. 265, Manfredi ■ Pekin, vii. 273, Kbgler ■ Ingolstadt, vii. 274 Pekin, 1727, 1728, vii. 418 — occulted by the moon, 1740, viii. 477, Beyis Jupiter's satellites, eclipses observed at Pekin, x. 3, Gaubil Lisbon, x. 567 ; xi. 158, Chevalier — observations of the eclipses of, recommended to be made by the French astronomers, xi. 520, Maskelyne — tables of the motions of, xi. 535, Dunthorne — problem respecting the duration of the shadow of the eclipses of, xii. 372, . , Witchell — eclipses of the 1st observed at Glasgow, xii. 67 0, Wilson ; compar. observ. at Greenwich, xii. 67 1, Maskelyne — eclipses of the 1st satellite, at Funchal, xiii. 82, Heberden — on perfecting the theory of, xiii. 422, Bailly ; Notes on Mr. Bailly's paper, xiii. 430, Horsley — eclipses of, observed near Quebec, xiii. 526,. . . . Holland ■ at Gaspel, ibid, Sproule North America, xiii. 527, Holland — comparison of observations at Greenwich, with those at North America, xiii. 527, Maskelyne — eclipses ot the 1st satellite at Anticosti, xiii. 528, Wright — of their changeable brightness, rotation, and diameters, xviii. 187, Herschel Jurin, James, m, d., biographical account of, vi. 330, Note — ascent of water in capillary tubes, ibid, and 432 — doctrine of the motion of running water, vi. 336, 5Q5 — Roman inscription near Carlisle, vi. 362 — muscular motion of the heart, vi. 375 ; reply to Keill's epistle on the same subject, 427 — specific gravity of human blood, vi. 415 — on examining the specific gravity of solids, vi. 538 — on the infection of small-pox, vi. 601 — tables of the mortality of small-pox, vi. 6l0 — on making of meteorological observations, vi. 676 — measure and motion of effluent water, viii. 278, 298 — theory of the action of springs, ix. 18 — force of moving bodies, ix. 128 — dynamical principles, ix. 217 Justel, — — , an engine for consuming smoke, iii. 292 — an extraord. swarm of grasshoppers in Languedoc, iii. 319 — an ancient sepulchre in France, iii, 337 K Kanguroo, organs of generation and mode, xvii. 535, Home Kapanhihane, description of the bog of, iv. 206, Molyneux Kay, Jonathan, of an extraordinary cancer, iv. 643 Kearsly, Dr., of the comet of 1737, Philadelphia, viii. 153 solar eclipse, viii. 154 Keill, James, m. d., biographical account of, v. 299, Note — dissection of a man at 130 years old, ibid — on the propulsive force of the heart, vi. 415 Keill, John, m. d., biographical account of, v. 417, • • Note — laws of attraction, ibid — centripetal force, v. 435 — solution of Kepler's problem of the planets' motion, vi.l — theorems on the divisibility of matter, vi. 91 — inverse problem of centripetal forces, vi. 93 Keir, James, m. d., on the crystallizations on glass, xiv. 102 Keir, James, the freezing of vitriolic acid, xvi. 271 — dissolution of metals in acids, xvi. 695 Kelly, James, strata found in digging for mad, vii. 154 — fossil horns found in Ireland, ibid Kelp, how produced, ii. 459, Colwall Kepler, John, biographical account of, ii. 130, Note — of his manuscripts, ii. 132, Hevelius — solution of his prob. on the planets' motion, vi.l, Keill; viii. 177, Machin Kermes, grain of, its use, and preparation, i. 134, Verny — insect husks of, on plum-trees, i. 598, 607. ii. 7, Lister Kerkringius, — , m.d., on eggs in all sorts of females, i. 6^7 H2 50 RUT INDEX. SAL Royal Society, opinion of the committee on the shape of lightning-conductors, xiii. 3S2 — meteorological journal, 1774-, xiii. 6l5; 1775, xiv. 43; 1776, 179; 1777,391; 1778, 521; 1779, 682; 1780, xv. 87 ; 1781, 277; 1788, xvi. 556; 1789, 652; 1790, xvii.38; 1791, 192; 1792, 306; 1793, 389; 1794, 53^; 1795,752; 1796, xvm. 138; 1797, 315; 1798, 485; 1799, 666 descrip. of the meteorol. instruments, xiv. 49, Cavendish report of the commit, on the use of thermoms. xiv. 258 on an accident by lightning at Purfleet, xiv. 333 — donation by C. Rumford for a prize medal, xviii. 137 Ruby, table of the specific gravities of, xviii. 377 Rudbeck, Olaus, biographical notice of, i. 247, Note Ruminating man, account of a, iii. 457, Slare Rumford, Count, experiments on gun-powder, xv. 88 — new thermometrical experiments, xvi. 108 — product, of dephlogisticated air from water, xvi. 198 — relative absorption of moisture from the atmosphere by different substances, xvi. 260 — on the conducting powers of substances, xvii. 135 — method of finding the comparative intensities of light from luminous bodies, xvii. 359 — on the transparency of flame, xvii. 373 — experiments on coloured shadows, xvii. 374 — on the loss of light in passing through glass, xvii. 368 — superiority of Argand's to common lamps, xvii. 370 lamp to a candle, xvii. 371 — fluctuations of light from candles, ibid — relative quantities of light from wax, tallow, and oils, xvii. 372 — donation to u. s. for a prize medal, xviii. 137 — experiments on the force of fired gunpowder, xviii. 140 — loss of his private papers and philosophical memoranda, xviii. 155, Note — on the source of heat excited by friction, xviii. 278 — on the chemical properties of light, xviii. 378 — on the weight ascribed to heat, xviii. 4y6* Runic characters, of Helsingland, explanation of, viii. 114, Ctlsius Rupture, of a large umbilical, vii. 513, Ranby — dissection for an inguinal, with a pin found in the ap- pendix caeci, viii. 89 Amyand — an extraordinary inguinal, viii. 474, Huxham — consequences of an incomplete hernia, viii. 497, Le Cat — case of a navel rupture, ix. 41, Taube — cases of hernias with sacks, x. 221, Le Cat — dissection of a, x. 227, Same — of an uncommon large hernia, xii. 295, Carlisle — see Bubonocele. Russel, Alex., m. d., biographical account of, x. 667, Note — account of four undescribed fishes, ibid — description of an ascidia pedunculata, xi. 635 Russel, Patrick, biographical account of, xvi. 653, . . Note — of earthquakes in Syria, xi. 437 — practice of inoculation in Arabia, xii. 529 — account of the drug tabasheer, xvi. 653 Russel, Rich., of a scirrhous tumour in a cyst'13, vi. 73 Rusma, Turkish, manufacture and use of, iv. 304 Russia, Russian Asiatic discoveries, ix. 320, Euler — antiseptic regimen of the natives of, xiv. 395, . . Guthrie — treatment of persons afftcted by fumes of charcoal, xiv. 522, Same Rutherford, Thomas, d. d., agitation of the waters, 1755, Herts, xi. l6 Rutty, John, m. d., on the poison of laurel- water, viii. 297 — copper springs in Pensylvania, xi. 3 Rutty, John, m.d., differ, impreg. of mineral waters, xi.395 — of the Amlwch waters, and Hartsell Spa, xi. 429 Rutty, Wm., m. d., cloven spine with a tumour, vi. 4S7 — of a bony substance in the thorax, vii. 159 — tumours of the abdomen, vii. 277 — method of making tin plates, vii. 304 Ruysch, Fred., m. d., biographical account of, iv. 229, Note Rye, disorder from using a bad sort in France, ii. 357 — see Ergot, Corn. Rycaut, Sir Paul, of sable mice from Lapland, iv. 36l Saccheti, John Mendes, m. d., effects of the earthquake at Lisbon, November 1, 1755, x. 659 Sackette, Rev. John, subsiding of the earth in Kent, vi. 252 Saffron, culture and ordering of, ii. 423, Howard ; vii. 278, Douglas Sails, best form of, for mills and ships, ii. 509, Hook Saint Clair,, Robert, m.d., eruption of fire from the earth in Italy, iv. 320 — a lamp invented to preserve the wick, iv. 320 Saint, J. O., of the arcuccios used in Italy, vii. 528 Saint Helena, see Helena. Saint Paul's, see Lightning. Salamander, account of an Indian, i. 141, Steno; thelacerta salamandria described, ibid, Notes Salep, a new method of preparing, xii. 589, Moult Salien, Mr., case of a stone cut from the bladder, viii. 241 Saliva, remarks on the salivary vessels, iii. 86, . . Bartholine — a new salivary duct, iii. 241, Nuck — account of the salivary glands, &c, vi. 445, Hale — of an unusual colour, vii. 19, . . Hale Sal ammoniac, collected near mount iEtna, ii. 118 — production of cold with, ii. 654, Slare — natural, from mount Vesuvius, iv. 508, Silvestre — method of making in Egypt, xi. 433, Hasselquist Sal montis Vesuvii, how produced, iv. 507, Silvestre Salmasius, CI., biographical account of, i. 343, Note Salmon, Rev. Thomas, theory of music reduced to propor- tions, v. 243 Salt, a method of separating from salt water, i. 45 — strange propensity in a girl to eat it, i. 49, . . Oldenburg — process of making sea salt by the sun in France, i. 382 — a natural rock of, in Cheshire, i. 539, Martindale — and sand from brine, formation of, ii. 589, Plott — crystallization of sea salt, iii. 1 1, Lister — way of ascertaining the quantity of in waters, iii. 496, Boyle — method of making in China, iv. 696, .... Cunninghame — quantity of, in frozen sea-water, viii. 514, .... Middleton — art of making in different countries, ix. 520, Brownrigg — of a salt found on the peak of Teneriffe, xii. 195,Heberden Salts (chemistry) volatilization of salt of tartar, ii. 54, Coxe — a volatile salt from vegetables, ii. 124, Becke — fixed salts from vegetables, alike, ii. 158, 1 66, .. Coxe — of a salt from coal, ii. 359, Hodgson — distillation of fresh water from salt, iii. 1 1 — figures of salts from wines, cScc, iii. 146, 592, Leuwenhoek mineral and other substances, iii. 186, Same — table of salts from various vegetables, iv. 301, .... Redi — quantity of acid salt in acid spirits, iv. 483, . . Homberg — from tobacco leaves, v. 1 62, Leuwenhoek — from calcined hay, v. 193, Same — alkaline, from rotten wood, vi. 499, Robie — experiments on Epsom salts, vi. 662, Brown — analysis of Seignette's Rochcllc salt, viii. 10, . . Geoffroy — distillation of sea- water by wood-ashes, xi. 243, Chapman — varieties of, from vegetable acids ; peculiar nature of the salt of amber, xii. 479, Monro SAP INDEX. SGH 91 Salts (chemistry) hints to facilitate the making of neutral salts, xii. 484, Monro — an indissoluble salt from a putrid infusion of hemp-seed, xii. 616", I Ellis — solubility of certain saline substances in alcohol, xv. 295 Withering — specific gravity and attractive powers of saline substances, xv. 3, 236, 327, Kirwan — see Sea-water, Acids. Salt-petre, method of making in the Mogul's dominions, i. 38 Salt springs, at Hall in Saxony, i. 48 — at Lunenburg, i. 48 — at Droitwich, & Nantwich, inquiry concern., i. 132,Beale — at Nantwicb (answer to Beale's inquiries,) i. 397, 405, Jackson — goodness of the East Charnock spring, i. 419, Highmore — springs and manufacture at Droitwich, i. 463, . . Ratsel — a spring near Durham, iii. 78, Todd — springs in Spain, xii. 342, Bowles Salt (mines) in Transylvania and Hungary, i. 437, Brown — of the sal-gem mines in Poland, i. 46*9 — works of Soowar in Hungary, vii. 386, .... Bruckman Salvadora, [persica] genus of plants described, ix. 635, Garcin Salubrity, see Air. Samber, Robt, m. d., polypus coughed up from the wind- pipe, vii. 188. Sampson, Henry, m. d., instance of inverted bowels, ii. 155 — case of dropsy in the ovarium, ii. 437 tumours in the ovarium, ii. 501 — of a child of 6 years with a woman's face, iv. 31 Sanctorius, Sanct., biographical account of, ii. 412, . . Note Sand, of a sand-flood at Downham, i. 264, Wright — remarks on, and a table of sands, iii. 82, 84, .... Lister — experts, on shining sand from Virginia, iii. 495, Moulen — some magnetical sand, iv. 310, Butterfield — figures of various sorts, v. 94, Leuwenhoek — a petrifaction of, xiv. 479, King Sandal, and part of a woman's body, found in a morass, and preserved by the water, ix. 364, Stovin; Mr. Catesby's remarks on the sandal, 366, Note ; Mr. Vermes' re- marks, ibid Sanderson, Win., magnetic variations in the Baltic, vi. 498 Sand-piper, two species of tringa from Hudson's Bay, xiii. 344, Forster Sandius, Christopher, origin of pearls, ii. 126 Sandwich, Earl of, remarkable halos about the moon, i. 146 Sandys, Francis, case of hydrophobia, viii. 205 Santerini, a new raised island near, v. 407, Sherard . . - — ■ ■- v. 44:6, .... Bourgignon v. 647, Goree Sap, on the motion of, i. 304, 318, Beale and Tonge; addi- tional remarks, 332, Tonge — to make a fermented liquor of, i. 334, Tonge — on the motion of, i. 354, Willughby and Ray i. 423 Tonge, Willughby — bleeding of sycamores, black poplar, i. 441, Willughby — journal of the bleeding of the sycamore, i. 556, 558, on other trees, 559 5 of the mulberry as recorded by Pliny, i. 559, Lister — barometrical use of the running of sap, i. 559, • • Tonge — on retarding the ascent of, i. 259, Tonge — inquiries on the running of sap, i. 56l — motion and circulation of, i. 576, Lister ; Willughby's remarks on Lister's observations, 578; reply by Lister, 579 — experiments on the motion of, vi. 234, Bradley vii. 36, Fairchild Sapphire, table of specific gravities of, xviii. 377 Sarcocele, see Hydrosarcocele. Sarmento, Ja. de Castro, of diamonds in Brazil, vii. 508 — astronomical observations at Paraguay, ix. 6l3, 6l5 Sarotti, Sign., of a red snow at Genoa, ii. 432 Sartorius, observs. at Madras of the comet, 1737, viii. 154 Sassafras, the oil of, crystallized, viii. 243, Maud Satellite, its motion dependent on the shape of the planet, xi. 295, Walmsley — see Jupiter, Herschel. Saturn, observation of by Mr, William Ball, i. 54 i. 84, . . Hook ' i. 326, Huygens and Pitcaim — the ring, i. 529, Hevelius — appearance of the ring, i. 530, .... Huygens and Hook — observation of, 1671, i. 657 , Cassini ; 659,. . . .Hevelius Saturn, occultation by the moon 1671, i. 658, Same — appearances of 1 67 1, i. 66*0, Flamsteed — discovery of 2 new planets, and some fixed stars about, ii. 50, 377, Cassini — appearance of (I676) ii. 333, Same — occultation by the moon (1678) ii. 432, Bulliald — motion of the 4th satellite, ii. 584, Halley — observs. of conjunctions with Jupiter, ii. 637, Flamsteed — 3 conjunctions with Jupiter, 1682-3, ii. 662, . . Hevelius — account of 2 new satellites, iii. 292, Cassini — occultation by the moon, 1687, iii. 350, Haines — theory of the 5 satellites corrected, iii. 363, .... Cassini — motions of the satellites of, vi. 349, Pound — observs. on the satellites of, vi. 665, Hadley — disparition of the ring observed, xiii. 509, .... Varelaz — observation of a belt on its disc, xiv. 108, Messier — determination of its longitude and node, xvi. 177, Biigge — description of, and discovery of 2 new satellites, xvi. 6l3, Herschel — rotation of, and tables of the satellites, xvi. 730, . . Same — on its ring, and rotation of the 5th sat., xvii. 117> Same — observ. of a quintuple belt on, xvii. 345, Same — rotation of on its axis, xvii. 356, Same Savard, M., of a foetus lying outside the uterus, iv. 110 Savery, Servington, magnetical observs. and experts, vii. 400 — account of his improved micrometer, x. 359 Savery, Thomas, engine for raising water by fire, iv. 398 Savile, Ann, account of Henry Jenkins, iv. 92 Sault, R., investig. of the curve of swiftest descent, iv. 335 Saumarez, H. de, machine to meas. a ship's way, vii. 126, 338 — observations of tides in the Thames, vii. 133 Saunders, Robert, vegetable and mineral productions of Boutan and Thibet, xvi. 539 Saunderson, Wm., observation of the comet of 1723, at Bombay, vii. 176 — lunar eclipse at Gomroon in Persia, ibid Scales, of the mouth, &c. microscopical observs. on, iii. 43, Leuwenhoek Scales, of fish, on the scales of eels, iii. 125, Same — microscopical observations of, iii. 592, Same Scallop, dissection of the, iv. 170, Lister Scarabaeus galeatus pulsator, see Death Watch. Scarborough Spa, on the exist, of alum in, i. 419, Highmore Scarburgh, Mr., effects of a storm in the rivers of North America, iv. 198 Schefferus, answers to queries : utility of the r. s. i. 127^; nature of amber, ibid ; on swallows, ibid ; animals be- coming white in winter, 128 ; fishes in ice, ibid; freez- ing of oil or brine in Sweden, ibid Schelhammer, G. Ch., on Greek surgical, mss. v. 675 Scheuchzer, John James, biograph. account of, v. 136, Note — solar eclipse, 1706, at Zurich, v. 208 M 2 92 SEA INDEX. SEM Scbeuchzer, J. J., lunar eclipse, 1707, at Zurich, v. 350 — barometrical experiments in Switzerland, vi. l66 — dissection of a person aged 109, vi. 652 — account of earthquakes in Sicily, 1693-4, 1717, vii. 46. — petrified human skeletons, vii. 129 — anatomy of the marmot, (mus alpinus), vii. 181 — discovery of some rare crystals, vii 1 87 — plan of a botanical history of Switzerland, vii. 512, Scheuchzer, J. G-, to measure heights by the barom. vii. 264 — on the height of several mountains, vii. 2S2 — bills of mortality of several towns in Europe, vii. 345 Schihallien, observs. to find the attraction of this mountain, thence to reduce the earth's density, xiii.702, Maskelyne — survey of the same, for the same purpose, xiv. 408, Hutton Schlichting, John Daniel, medico-chirurgical observs.viii.620 Schlosser, John Albert, action of quick-lime on volatile alkali, x. 612 — description of a specimen of alcyonium, x. 671 the chcetodon rostratus, xii. 110 Schmeisser, John Godfrey, analysis of the Kilburn Wells water, xvii. 149 — instrument for the spec. grav. of fluids, xvii. 3l6 — physical and chemical characters of, xvii. 446, Schmeisser Schotte, J. P. m. d., state of the weather at Senegal, xiv. 711 — extraordinary case of sarcocele, xv. 345 Schroeter, John Jerome, atmospheres of Venus and the moon, xvii. 232 — observs. of the solar eclipse, Sept. 1793, xvii. 422 — mountains, rotation, atmosphere, &c. of Venus, xvii. 506 Schurman, Anna Maria, anecdote of, i. 146 Schwaediawer, m. d., an account of ambergris, xv. 389 Scilly, alteration in the number and extent of the isles of, x. 324, Borlase — on a current to the westward of, xvii. 325, .... Rennell Scirrhous tumour, see Tumour. Sciurus volans, see Squirrel. Scolopendra marina, (aphrodita aculeata) iv. 133, 368, Molyneux Scoria, similarity between the scoria of iron-works, and some productions of volcanos, xv. 182, More Scotland, remarks made in, ii. 210, 226, Mackenzy — observations in the western isles, iv. 212, Martin — curiosities, and literary information from, iv. 526, Sibbald — observations on the nat. hist, of, vi. 21, Lhvvyd — strata and volcanic appearances in the western isles, xvi. 639, Mills Scott, J., case of an imperfect sight, xiv. 394 Scott, Wm. m. d., asthma occasioned by ipecacuanha, xiv. 18 Screw, a new method of applying the, xv. 28, .... Hunter Scurvy, extraor. effects of at Paris, l699» v. 454, . . Poupart — of securing the seamen from, on a voyage, xiv. 58, Cook »— observations on, and its treatment, xiv. 401, . . Mertans Scurvy-grass, of Greenland, remarks on, viii. 391 , Nicholson Sea, inquiries concerning the, i. 1 18, Boyle — observ. on the blowing of the wind at, i. l68, Colepresse — effect of the sea air on iron, meats, &c. i. 173 — difference in the water of, at different latitudes, i. 174 — cause of the saltness of, vi. 169 — machine for measuring the depth of, vii. 275, Desaguliers — unusual agitation of, 1756, xi. 1 , Prince — agitation of, at Antigua, Nov. 1755, xi. 9, Affleck at Barbadoes, March, 1761, xi. 6 1 4, Mason at Mount's Bay, Cornw.,xi. 60 1,621, Borlase — cause of its luminousness, xii. 680, Canton — temperature at great depths on the coasts of Lapland and Norway, xiii. 9, Douglas — of white spots observed in, at night, xiii. 289, Newland Sea, see Navigation, Tides, Currents. Sea-water, inquiries concerning the qualities of, i. 119, Boyle — method of making sea-water sweet, i. 549, • • • • Hauton — an improved method, ibid, and xi. 245, Notes — on the temperature and saltness of, x. 195, Ellis — Mr. Appleby's process of sweetening, x. 327, . . Watson — methods of distilling, x. 635, Hales — distillation of, writh wood-ashes, xi. 243, .... Chapman — bad effects from the medicin. use of, xii. 177, Lavington — specific gravity of, xiv. 35, Nairne — see Salt (Chemistry.) Sea animals, anatomy of the sea-fox, ii. 290 sea-calf, iii. 391 — account of the sea-calf, viii. 658, Parsons — description of the eye-sucker, ix. 15, Baker — of the sea-millepes [terebella] xi. 326, Peyssonel — of the ascidia pedunculata, xi. 635, Russell — description of the sea-pen, xii. 41, ., Ellis — of the sea-pen of South Carolina, xii. 44, Same — on the teeth of the sea-wolf [anarrichas lupus], xv. 541 , Andre — description of a new sea-animal, xvi. 1, Home ; anato- mical account of the same, 4, Hunter — anatomical description of the sea-otter, xviii. 34, Home and Menzies Sea-charts, division of meridians in, iii. 224, Wallis Sea-plant, see Plants. Sea (instru. used at), to find the depth without aline, i. 154 — to ascertain the force of the wind at, i. 157 — to measure the gravities of salt water, ibid — to fetch up water at any depth, ibid — see Navigation, Sea-water. Sealing-wax, light produced by attrition of, v. 452,Hauksbee Seamen, inquiries to be made by them, i. 50, .... Rooke i. 53, 153, Hook Seba, Albertus, biographical account of, vii. 340, . . Note — culture of cinnamon at Ceylon, ibid — anatomical preparation of vegetables, vii. 436 — of the curiosities in his museum, vii. 667 Secants, on the collection of,andon sea- charts, iii. 224, Wallis — demonstration of the sum of iv. 68, Halley — remarks on Dr. Halley's demonstration, x. 89 Secretion, on the nature of animal, v. 492, Keill Seddon, Rev. John, appearance accompanying an earth- quake, x. 114 Seeds, of plants, micros, observ. on, vi. 527, Leuwenhoek — of the musk scabious, angelica, grains of paradise, maple-tree, observations on, ix. 80, Parsons — micros, observ. on some minute, x. 8, Miles ibid, Baker — experts, on the preserving of, xi. 373 ; method of pro- ving acorns, xii. 514, Ellis — see Plants, Vegetables. Seeds (particular) microscop. observs. on orange-seeds, v. 6l, Leuwenhoek — observations on the seeds of polypodium, v. 197, Same — description of the seed of fern, viii. 505, Miles — vegeta. of melon seeds after 42 years, viii. 577, Triewald 33 years, ix. 100, .... Gale — of mushrooms, observs. on, viii. 718, Pickering — on the seeding of moss, ix. 200, Hill Seehl, Ephraim Rinhold, to procure sulphuric acid, ix. I Segner, J. A., m. d., machine to show solar eclipses, viii. 5 10 Seip, J. P., m.d., of a sulphur, cavern at Pyrmont, viii. 204 Sellers, Mr., magnetical experiments, i. 1 66 j discoverer of the artificial magnet, i. 167 Semen, triple nature of, i. 242, Van Horn SHE INDEX. SHO 93 Semen, single nature of, i. 271 , De Graaf — on the course of, i. 303, Note — animals in sem. masc, ii. 451, 473, iv. 419, 541, 668, Leuwenhoek — nature of spermatic animals, ix. 608, Needham — observations on the passage of, x. 9j Haller — see Generation. Seminal vessels (see Vasa Deferentia ; Generation, fyc.) Senegal, account of, and of a putrid disorder at, xiv. 713, Schotte Senckenberg, C. H., analysis of Cheltenham water, viii. 523 Senex, John, biograph. notice, viii. 17 6, Note — account of his celestial globe, ibid Senex, Mrs., letter recommending her husband's globes, ix. 700 Sennertus, biograph. notice of, ii. 237> Note Sense, on the organs of, viii. 6l9, Le Cat Septali, Manfredi, on rinding quicksilver at the roots of plants; and shells on inland mountains, i. 173 Sepulchral inscrip., found at Bonn, 1755, xii. 633, Strange Sepulchral monuments, see Monuments. Serapis, descrip. of the temple of, at Pozzuoli, xi. 106, Nixon Series, general method of infinite, x. 127, Simpson — on infinite series and logarithms, x. 397, Dodson — to determine the distinct sums of a, xi. 278, . . Simpson — new method of computing, xi. 441, Landen ■ — of certain infinite series, xii. 14, Bayer — to find quickly-converging series, xiv. 84, Hutton — of an infinite series of decreasing quantities, xiv. 131, Maseres — on very slowly converging series, xiv. 451, Same — on the sums of infinite series, xv. 309, Vince — summation of series, xv. 586, Waring — on infinite series, xvi. 6l, xvii. 43, Same — new method of investigating the sums of, xvii. 78, Vince computing the value of slowly-converging series, xviii. 312, Heliins — to obtain swiftly-converging series, xviii. 408, .... Same — summation of slowly-con verg. series, xviii. 415, 599, Same Serpents, of the capra (or cobra) capella, i. 307, • . Vernati — of the boa constrictor at Congo, ii. 434 — symptoms attending the bite of, iv. 311, .... Goodyear — of two serpents of Ceylon, iv. 650, Strachan — to distinguish those which are venomous, xvi. 523, Gray — see Vipers, Snakes, Rattlesnakes. Serpent-stone, of the pietra de cobra cabelos, or rhinoceros bezoar; its virtues and how produced, ix. 655, Sloane Serra, Correa de, on the fructification of submersed algae, xviii. 68 — a submarine forest on the coast of England, xviii. 479 Serum, see Blood. Sewell, Rev. Wm., demonstration of Newton's binomial theorem, xviii. 33 Sex, regularity in the number of males and females born, v. 606, Arbuthnot Sex of plants, see Plants. Shark, account of the blue shark, xiv. 423, Watson Sharp, Abraham, biographical account of, v. 294, . . Note Sharp, Samuel, biographical notice of, x. 357, Note — method of opening the cornea of the eye, ibid, and 414 — experiments on the agaric of oak for haemorrhage, x. 479 Sharp, Wm., a new instrument for fractured legs, xii. 391 Shaw, Rev. Thos., biographical account of, vii. 364, Note — geographical description of Tunis, ibid Sheep, of a lamb suckled by a wether, iii. 678, Kirke — a horn growing from the throat of a, x. 601, Parsons Sheerman, Bazaleel, extraordinary surgical cases, viii. 326 Sheldrake, Timothy, of a monstrous child, viii. 401 Sheldrake, Timothy, steel-yard swing for curing deformities, viii. 549 Shells, found on inland mountains, i. 173, Septali — remarks on fossil shells, i. 645, Lister — answers to queries respecting, iii. 501, Same — found in the East Indies, iii. 573, Witzen — petrifactions of marine shells, &c, iv. 66, Scilla — observed in Scotland, iv. Ill, Sibbald — from the Isle Ascension, cata. of, iv. 418, Cunninghame — of a bed of oyster shells in Berkshire, iv. 471, • • Brewer — fossil fish, in a quarry in Lincoln., iv. 521, De la Pryme — fossil shells at Harwich Cliff, v. 1 24, Dale — fossil shells, &c. in Northamptonshire, v. 284, Morton — a methodical table of, vii. 629, Brayne — on Le Bruyn's account of petrif. oysters, viii. 455, Klein — remarks on the hardness of, ix. 15, Collinson — of crabs, on the casting of, x. 254, Parsons — of some minute British shells, xvi. 80, Lightfoot — analytical experts, on shells, xviii. 554, Hatchett Shell-fish, on the copula, of the pholas kind, iii. 107, Lister — pholas dactylus lodged in a stone, ix. 439, • • . . Parsons — description of the pholas conoides, xii. 174, Same — see Barnacles, Cancer, Crab, Muscles, Pholas, Scallop. Shepherd, Samuel, of an explosion in the air, viii. 384 Sherrard, Wm., m.d., biographical account of, vi. 314, Note — several sorts of China varnish, iv. 482 — of a new-raised island in the Archipelago, v. 407 — description of the genus Araliastrum, vi. 314 — of the poison-wood tree of New England, vi. 508 Sherburne, Edward, biographical notice of, ii. 185, . . Note Sherman, B., extraordinary case of costiveness, r. 247 — bones of a calf taken from the cow's uterus, v. 532 — part of the os femoris supplied by a natural callus, ibid — three unusual surgical cases, viii. 326 Sherwood, Noah, remarkable stones from the kidneys, viii. 462 Sherwood, James, eels of paste, viviparous, ix. 202 Shervington, W. transit of Mercury over the sun,1753, x. 414 Shetland, account of the Island, ix. 44, Preston Shield, materials and forma, of a Roman, iv. 279, Thoresby Shining fish, observations and exper. on, i. 75, Beale i. 211, Boyle Shining wood compared with burning coal, i. 215, . . Same Shining flesh, remarks on, ii. 31, Same ii. 294, Beale — on light emitted from various bodies, xviii, 630, Hulme Ships, to preserve from being worm-eaten, i. 65, ii. 123 — progress of naval architecture, i. 650, Witsen — of ancient shipping, i. 678, Meibomius — method of rowing in a calm, vi. 545, Du Quet — method of bending planks for, vi. 577 > Cay — to stop the leakage of worm-eaten bottoms, ix. 125, Cook — method of protecting from lightning, xi. 660, . . Watson — method of preserving stranded ships, xiv. 625, Bernard — propositions for determining the stability of, xvii. 682, xviii. 315, Atwood — see Navigation. Shipton, John, excision of part of a dog's intestines, v. 4 — successlul use of bark in mortifications, vii. 574 Shipton, Sir Philip, bones of a foetus voided through the groin, v. 246 Shipwreck, effects of, on the mariners, xvii. 193 Shirley, Thos., of a well taking fire at a candle, i. 169 Short, James, biographical account of, xi. 649, Note — aurora borealis 1736, viii. 412 — observations of meteoric lights 1737, viii. 460 — solar eclipse, Dec. 1739, viii. 470, July 1748, ix. 591 ; April 1764, xii. 112 94 SIL INDEX. SKI Short, James, lunar eclipse 1740, viii. 470} 1749. '*• 69s ; 1750, x. 11, 95; 1751,2205 1760, xi. 510; 176*2, xi. 632 — observation of a supposed satellite of Venus, viii. 476 — description and use of an equatorial telescope, ix. 695 — remarkable appearance in the moon 1751, x. 175 — of Mr. Serson's horizontal top, x. 229 — of the several inventions to remedy the irregularity of the pendulum arising from heat or cold, x. 283 — account of Frisi's work on the earth, x. 305 — of Savery's improved micrometer, x. 359 — transit of Mercury over the sun 1753, x. 370 — colour of the rays of light from Jupiter, x. 393 — remarks on Euler's theorem on the aberations of tele- scopic glasses, x. 401 — astronomical observations in London 1753, x. 408 — observations on a transit of Mercury, x. 426 ■■ the comet seen January 176O, xi. 428 — transit of Venus over the sun, June 1761, xi. 553 — on observations of the going of a pendulum clock, xi. 631 — determination of the sun's parallax, xi. 649, xu- 22 — - difference of longitude of Greenwich and Paris, xi. 713 — solar parallax deduced from a transit of Venus, xii. 157 — state of the thermometer Jan. 1740 and 1768, xii. 508 — method of working glasses of refracting telescopes truly spherical, xii. 69 1 Short, Thomas, m. d., imposthumation of the liver, vii 500 — account of several meteors, viii. 469 — of an extraordinary dropsy, viii. 607 Short-hand, elements of, ix. 51 6, Jeake — remarks on Mr. Jeake's plan, ix. 530, Byrom Lod wick's plan, ix. 534, Same Shoulder, see Os Humei i. Shrew (quadruped) 2 species of, from Hudson's Bay,xiii. 330 Forster Shrike (bird) from Hudson's Bay, xiii. 332, Forster Shrine, of Croyland Abbey, account of, ix. 590, .. . Stukely Shuckburgh, Sir George, biograph. account, xiv. 203, Note — barometrical measurement of heights in Savoy, xiv. 203 — comparison of his rules for measuring heights by the barometer, with those of Col. Roy, xiv. 405 — variation of the heat of boiling water, xiv. 537 — history of the invention of equatorial instruments and description of his own, xvii. 299 — - endeav. to fix a standard of weight & measure, xviii. 300 — table ofdeprec. of money since the Conquest, xviii. 309 Shuldham, Molyneux, on the sea cow, xiii. 643 Siam, longitude of, iii. 346 Sibbald, Sir Robert, biographical notice of, iii. 599, • • Note — description of shells found in Scotland, iv. Ill — stones voided by a boy, iv. 295 — curiosities, and literary information from Scotland, iv. 526 — description of the pediculus ceti, [lepas diadema,] v. 317 Siberia, geological and botan. ace. of, ix. 491 j x. 351,Gmelin — comparison of thermometrical observ. at, x. 344, Watson Sickness, an uncommon case of, ii. 90, » . . . . Kirk by Sidon, Phenician numerals used at, xi. 291, Swinton Sight, help for decayed sight, by tubulous spect. i. 266, 275 short-sightedness, ii. 508, Hook — case of a partial sight, vii. 44, Vater — restored after 13 years j observ. in consequence ; vii. 235 Cheselden — a new case in squinting, xiv. 297, Darwin — observations on squinting, xviii. 80, Home — a remarkable imperfection of, xvi. 394, Scott — see Eye, Vision, Microscope, Telescope. Sigorgne, P. de, impossib. of the Cartesian Vortices, viii. 424 fcilchester, descrip. of the ancient town of, ix. 86, 599, Ward Silk, average length of, in the pod or ball, i. 32, .... Note — nature and qualities of, iv. 380, Aglionby — account of the first discovery and use of, v. 542,. . . . Bon — experiments on the silk of spiders, ibid, Same — production of from worms in England, vi. 426, Bartram Silk-pod, of a particular sort, from America, xi. 332, Pullein Silk-worms, on the management of, i. 12, Digges — on the same, i. 30$ their generation, i. 32, Isnard — on the structure, growth, food, &c„ of, i. 367, Malpighi Silvabelle, St. Jacques, precession of the equinoxes, motion of the nodes, &c, x. 436 Silver, of the mines in Hungary, i. 441, Brown — micros, observ. on the solution of, v. 56, . . Leuwenhoek — shape of the particles of, dissolved in aquafortis, v. '368, Magliabechi v. 549, Leuwenhoek 170 Note — precipitation of, from nitrous acid by iron, xvi. 703, Keir Silvestre, P., m, d., ace. of some new books in Italy, iv. 504 — state of learning in Italy, iv. 506 — dissection of a woman dead in child-bed, iv. 560 Simmons Samuel Foart, m. d., stones voided through a fis- tulous sore in the loins, xiii. 507 Simon, James, bones of a fcetus voided per anum, ix. — mineral productions in Ireland, ix. 17 1 — petrifactions of Lough Neagh, ix. 282 — register of the weather at Dublin, 1752-3, x. 414 — journal of the weather at Dublin, 1753-5, xi. 41 Simpson, Thomas, biographical account of, ix. 464, . — motion of projectiles near the earth's surface, ibid. — on fluents of multinomials, ix. 513 — general method of infinite series, x. 127 — resolution of isoperimetrical problems, x. 560 j xi. 238 — advantage of taking means in astronom. observ. x. 579 — horary alteration of the earth's equator from the attrac- tion of the sun and moon, xi. 170 — to determine the distinct sums of a series, xi. 278 Simson, Robert, ll. d., biograph. account of, vi. 659, Note — two propositions from Pappus of Alexandria, ibid. — on converging fractions, x. 430 Sinai, journey to the written mount, in, xii. 278, Montagu Sinclar, George, biographical account of, i. 380, .... Note Sinclair, John, a delineating machine, ii. 85 Sinking, of part of a hill in Ireland, vi. 69, Bp. of Clogher — of the earth in Kent, v. 352, Sackette ; further particu- lars, xvi. 91, Lyon — of trees in die ground, vi. 348, Neve — of the ground in Kent, vii. 273 near Auvergne, viii . 376, M. T. — a piece of ground in Norfolk, ix. 169, Arderon Siphon, similar in effect to that of Wurtemb. iii. Ill, Davis — similar to that of Wurtemburg, iii. 112, Papin — account of that of Wurtemburg, iii. 249, Reisil Siren lacertina, description of, xii. 322, Ellis — — — • anatomy of, xii. 360, Hunter Sirius, parallax and magnitude of, vi. 443, Halley — on discovering the annual parallax of, xi. 501, Maskelyne Sisley, J., of a calculus extracted from the scrotum, viii. 405 Six, James, of an improved thermometer, xv. 195 — of the variation of local heat, xv. 609 ; xvi. 404 Skeleton, with back-bone, ribs, tec. united, iv. 10, Connor — - of a large human, vii. 213, Degg — the bones of which were conjoined, viii. 51 6, Bp. of Cork — see Bones. Skelton, Rev. P., account of the cornel caterpillar, ix. 500 Skin, use of the pores, in the hands and feet, iii. 35, Grew — microscopical observations on, iii. 504, 56'2, Leuwenhoek ■ on an elephant's skin, v. 6'99, Same — of a distempered skin, vii. 543, Machin j x, 562, Bakei SMA INDEX. SNO 9S Skin, remarkable cutaneous disease, viii. 59, Vater on the different colours of people, ix. 50, Mitchell cure of an extraordinary disease of the, x. 475, . . Crusio — separation of the cuticle after a fever, xiii. 71, • • Latham Skins, Indians' method of dressing deer skins in America, iii. 458, „ . . . Southwell Skull, of a deformed human skull, iv. 372, Dupre — remarks on the above paper, ibid, Cowper — an extraordinary fracture, v. 435, Amyand Slare, Frederic, m. d., on solid and liquid phosphorus, ii.505 — further experiments on phosphorus, ii. 518 — philosophical experiments before the r. s. ii. 651 — analysis of, and exper. on, human calculi, iii. 18, 317, 319 — particulars of a ruminating man, iii. 457 — effects of air on transparent liquor, iii. 581 — oils that efferv. or explode with or without flame, iii. 663 — product, of effervescence, with 2 cold liquors, iii. 664 — births, deaths, &c. at Frankfort 1695, iv. 169 — examen of chalybeate waters, vi. 61 — of a new set of teeth at 80 years of age, vi. 72 — nature of Pyrmont and Spa waters, vi. 280 Slate, method of estimating the goodness of; and on its use as a covering for houses, i. 377, Colepresse — on the nature of Irish slate, iv. 298 Sleep, case of extraordinary sleepiness, v. 277, Oliver Sloane, Sir Hans, biographical account of, iii. 425, . . Note — description of the pimenta, iii. 425 1. — wild cinnamon tree, iii. 427 ■ .. two plants from the Cape, iii. 513 — effect of eating dog-mercury, iii. 575 — description of the cortex winteranus, [drymis] iii. 586 — description of the cuntur [condor] of Peru, iii. 622 — the coffee shrub, iii. 623 4 sorts of beans from Jamaica cast on shore in Scotland; reflections how floated thither, iv. 103, Sloane — fossil tongue, dug up in England, of an American marine animal, iv. 200 — on the use of ipecacuanha for looseness, iv. 239 — of a Chinese cabinet, &c. iv. 324, 345, 349, 352 — of several plants of Jamaica, iv. 362 — dropsy in the ovarium, iv. 375 •— remark respecting stones, &c. found in Jamaica and En- gland, iv. 381 — on the swallowing of stones, iv. 381 • — account of the bogs in Ireland, v. 636 — of large horns found at Wapping, vii. 180 — remarks on fossil bones of elephants, vii. 240, 255 — medicinal quality of henbane, vii. 6l0 — of the fascinating power of the rattle snake, vii. 655 — a remarkable calculus from the bladder, viii. 242 — on hairy excretions from the body, viii. 490 — description of the gorgonia verrucosa, ix. 198 — of the rhinoceros bezoar, or serpent stone, ix. 655 — various trials of inoculation, x. 690 Sloane, Wm., discovery of the city Aretina, viii. 402 Slow-worm, its bite innoxious, xi. 6l4, Forster Slusius, R. F. W. biographical account of, i. 327, Note — method of drawing tangents to all curves, ii. 38, 74 — solution of Alhazen's problem, ii. 97, 107 Small, Alex., account of the island of Minorca, xiv. 68 Small-pox, case of a woman delivered of a dead child which was covered with pustules, vi. 42, Derham — of a child which had it in the womb, xv. 123, . . Wright 1 — on the infection of, vi. 601, Jurin — * inoculated and natural, mortality of, vi. 608, . . Nettleton ■ v. 610, Jurin • — of an anomalous sort in 1724-5, vii. 110, .... Huxham — effects of, at Hastings, vii. 480, Frewen Small-pox, discharge of bloody urine in, viii. 708, . . Dodd — use of the Peruvian bark in, ix. 369, Wall j ix. 131, Baily — two days after birth, ix. 692, Mortimer — foetus in utero, affected by, ibid, Watson xiv. 628, Hunter Smalt, method of preparing, v. 165, Krieg Smeathman, H., nat. hist, and econ. of the termites, xv. 60 Smeaton, John, biographical account of, x. 67, Note — improvements on the mariner's compass, ibid — improvements in the air-pump, x. 247 — description of M. de Meuron's steam-engine, x. 252 — new combination of pulleys, x. 278 — machine for measuring a ship's way, x. 456 — a new pyrometer, x. 482 — effects of lightning on a church and steeple, xi. 113 — different temperature of the air at Edystone and Ply- mouth, xi. 191 — experiments on water-mills and wind-mills, xi. 338 — on the menstrual parallax of planets, xii. 535 — celestial observations made oat of the meridian, xii. 542 — solar eclipse, 1769, observed at Leeds, xii. 648 — a new hygrometer, xiii. 127 — on mechanic impelling powers, xiv. 72 — experts, on the collision of bodies, xv. 295 — graduation of astronomical instruments, xvi. 30 — Hindley's method of dividing circles, xvi. 40 — right ascension and declination of mercury, xvi. 292 Smelts, on the degenerating of, vi. 619, Dudley Smethurst, Gamal., Chinese arithmetical instrument, ix. 625 Smethwick, Francis, to grind optic and burning-glasses,i.226 Smith, Caleb, improvement of catadioptrical telesc, viii. 393 Smith, Dr. Edw., exper. on a soap-earth near Smyrna, iv. 80 Smith, J. E., m. d., on the irritability of vegetables, xvi. 421 Smith, Rob., successful treatment of hepatitis, xii. 289 Smith, T., d. d., observ. relating to Constantinople, ii. 664 — account of parts of Turkey, iii. 1 — currents at the Gibraltar Straits, iii. 30 — journal of a voyage to Constantinople, iv. 176 Smith, Wm., a fire ball seen in the air, July 1750, x. 124 — transit of Venus, 1769, Philadelphia, xii. 649 Mercury, 1769, Philadelphia, xiii. 83 Smith, P., on the structure of the eyes of birds, xvii. 557 Smithson, Rich., on the winds in an E. India voyage, i. 375 Smoke, an engine for consuming, iii. 292, Justel Smyth, Edw. m. d., on the petrifying power of Lough Neagh, iii. 195 — use of opium among the Turks, iv. 101 Snails, of two uncommon sorts, i. 377 ; considered a delicate food by the Romans, ibid; generation of, ibid, Note — different sorts of, ii. 138, Lister; queries respecting, ibid j answers to queries, 139; table of English snails, 140 — on the breeding of, ii. 668, and note, ibid — on the eggs of, iv. 223, Leuwenhoek — . reviviscence of, after being many years in a cabinet, xiii. 565, Macbride — see Limax. Snake, differt. mode of brooding, of snakes and vipers, i. 49 — death of, by swallowing a porcupine, ix. 102,. . Wollaston — see also Rattle-snake, Serpents. Snake-stones, inefficacy of, ii. 58, Redi Sneyd, T., convers. of the subst. of a bird into fat, xvii. 192 Snipe, of a new species [tringa lobata], xi. 130, ..Edwards Snow, method of preserving with chaff, i. 50, Ball — of an unusual kind of, i. 278, Beckman — external and essential nature of, ii. 54, Grew — of a red colour, at Genoa, ii. 432, Sarotti — of a woman living 6 days under, without food, vi. 69, Bowditch 96 SPE INDEX. SPR Snow, observations on the figures of, vi. 644, . . Langwith — figures of flakes of, viii. 577, ~ Stocke — configuration of the particles of, xi. 1, Nettis — of a family overwhelmed in their cottage by, xi. 41, Bruni — of the quantity of water in a fall of, xii. 338, Brice Soals (fish) shell-fish the food of, ix. l6, Collinson Soap, to make soap-lees for medicinal uses, viii. 565, Geoffroy — efficacy of, in curing the stone, ix. 340, Lucas « xi. 122, Pringle i xi. 161, Whytt Soap-earth, near Smyrna, (carbonate of soda) iv. 80, Smith Soap-tree, account of the, i. 230, Note Soil, singular appearance, on opening a well at Hanby, xv. 117, Englefield Solander, Dan. Cha., m. d., biog. account of, xi. 669, Note — account of the gardenia (cape jasmine) ibid — of hump-backed perch in Sweden, xii. 421, Note — transit of Venus, 1769, at Otaheite, xiii. 177 Solids, of the lunula, to find the dimens. of, iv. 505, Demoivre — on the solid of least resistance, iv. 54.5, Craig Solstices, observations for determining, xiii. 277, Witchell Solutions, that may be called cold, exp. on, iv. 6l 1, Geoffroy Solway moss, irruption of, xiii. 305, Walker Somersham water, analysis of, xii. 275, Layard ibid, Morris Son, M. du, method of breaking rocks, i. 28 — improvement of optic-glasses, i. 36, 41 Sorbus pyriformis [domestica], account of, ii. 434, .... Pitt Sorea, damage by a volcanic eruption at, iv. 13 Sound, degree of velocity of, iii. 633, Note — experiments on the motion of, iv. 338, Walker — on the ring, of a bell in vacuo, v. 202, 203, 499, Hauksbse — experiments and observations on, v. 380, Derham ; table of 1 he degrees of velocity as estimated by different authors, ibid; Mr. D.'s conclusion of the velocity, 393 ; remarks on echos, 394 — nature and properties of, v. 471, Grand i — on the propagation of, through the air, v. 500, Hauksbee ■ . 1 water, ibid, Same — velocity compar. with that of electricity, ix. 440, Watson — experts, and inquiries on the nature of, xviii. 604, Young — see Music. South, Captain, number of houses and hearths in Dublin, 1 696-7, iv. 481 — number of sea-faring men in Ireland, 1697, iv. 481 — — of people in Ireland, 1696, iv. 482 of Romish clergy in Ireland, 16.98, ibid South Sea, some islands discovered at various times, xii. 269, Hornsby Southwell, Sir Robert, description of Pen-park hole, ii. 551 — of dressing deer skins in America, iii. 458 — damage in the Isle of Portland, 1696, iv. 198 — on preserving flowers, fruit, &c. iv. 230 — of a monstrous calf with two heads, iv. 240 — to give various tinctures to water, iv. 243 — to give to iron a copper colour, iv. 304 — method of gilding silver, iv. 305 — some philosophical experiments, iv. 317 Southwell, Robert, esq., extraordinary echos, ix. 253 Spa Water, see Waters (mineral aud medicinal). Spain, geological remarks on the north of, xii. 340, Bowles Spar, on the formation of, xii. 384, King — a remarkable sparry incrustation, xiii. 439, Same Sparrman, Andreas, m. d., description of the honey-bird, [cuculus indicator] xiv. 1*28 Speaking Trumpet, see Trumpet, Specific gravity, of various bodies, experiments on, iii. 138 — see G ratify (specific). Speculum, to make concave parabolic specula, iv. 222, Gray — on glass specula, viii. 393, Smith Speech, recov. by means of a frightful dream, ix. 465, Squire — see Deaf and Dumb, Tongue. Spelter, description of, ix. 305, Mason S pence, Joseph, curiosities found at Herculaneum, x. 447 Sperma-ceti, see Whale. Spermatic vessels, anastomoses in, vii. 420, Mortimer Sphere, meridional parts of a spheroid, viii. 514, Maclaurin - — see Globe. Spheroid, fig. of the shadow of a prolate, xii. 372, Witchell Sphondylium vulgare hirsutum, on a mistake of Gmelin's respecting this plant, x. 355 Sphynx elpenor, account of this insect, iii. 120, Molyneux Spiders, and toads, innoxious to swallow, i. 140, . . Fairfax — of the Bermudas, remarkable web of, i. 284 — method of darting their threads, i. 379 i further parti- culars, 535 — table of 33 kinds, i. 601 , Lister ; natural economy of the spider, 600, Note — darting of the threads, iii. 46, Lister — natural history and economy of, iv. 587, • • Leuwenhoek — experts, of the manufacture of silk from, v. 542,. . Bon — poison of the bite of, vii. 20, Robie Spikenard [nardus Indica] an account of, xvi. 65S, . . Blane Spina ventosa, mercury a cure for, viii. 620, . . Schlichting — observations on the, ix. 245, Amyand Spine, case of a cloven, with preternatural tumour, vi. 487, Rutty — observation of a spina bifida, ix. 5, Aylett — experts, on the spinal marrow of living animals, xvii. 512, Cruikshank Spirit of wine, ascent of between planes, vi. 40, 41, Hawksbee — affinities of substances in, xvi. 79, Elliot Spirit-level, method of using at sea, vii. 620, .... Hadley Spirituous liquors, method of proportioning the excise on, xvi. 675, xvii. 263, Blagden; appendix to the report, xvii. 272, Gilpin — mixed with water, method of ascertaining the quantity of each, xvii. 426, Gilpin Spleen, remarks on the, i. 237, Behm — structure, use, &c. of, i. 324 Malpighi — on the texture of, i. 589, Same — observations on a diseased, iii. 460, Grew — micros, observ. on the structure of, v. 315, Leuwenhoek — observations on the glands of, vi. 262, Douglas — excision of a part of, viii. 263, Ferguson — cure of an abscess of, viii. 620, Schlichting Sponge, micros, observs. on, v. 266, Leuwenhoek — formation of, by worms, xi. 227, Peyssonel — nature and formation of, xii. 257, Ellis — uncommon sorts, on the coast of Italy, xiii. 32, Strange Spottswood, Mr, catalogue of plants at Tangier, iv. 85 Spout, of water, on the river at Topsham, iv. 12, . . Mayne — observed in the Downs, iv. 564, Gordon — water-spouts observed in the Mediterran., iv. 647, Stuart — observed in Yorkshire, iv. 709, De la Piyme — at Hatfield, v. 1 6, Same — in Lancashire, vi. 440, Richardson — at sea, vii. 606, Harris — in Cumberland, x. 18, Lock — raised from the land, x. 27 J , Ray — cause of water-spouts, x. 593, . . Eeeles SprengeU, Conrad, J., m. d., remarks on vipers, vi. (>1> — bills of mortality 1717, Germany, &c. vi. 6*81 1720, vii. 10 — experiments with Dr. Eaton's styptic, vii. 29 STA INDEX. STA 97 X Sprengell, Conrad J., m. d., bills of mortality of Dresden, 1617 to 1717, vii. 610 , Augsburg, 1501 to 1720, ibid Spring, a remarkable periodical one at Paderborn, i. 45 — another near Paderborn, with three streams of different qualities, i. 46 — at Alsace, producing an oily liquor, i. 48 — petrify, quality of a rivulet in Scotland, ii. 21 1, Mackenzy — origin of different sorts of springs, iii. 118, Plott — on boiling fountains, &c, iii. 136, 174, .... Robinson — eruption of a boiling spring, v. 680, Hopton — intermitting spring at Brixham, vii. 544, Atwell ■ — analysis of the hot spring near Tiberiades, viii. 556, Perry — depositing a blue sediment, ix. 254, Durant — a precipitate like white marble from mineral springs in Tuscany, xiii. 10, Raspe — of an unfreezing spring at Hudson's bay, xiii. 27, Wales — medicinal virtues of some hot springs at St. Miguel's, xiv. 393, Masson — temperature of, in Jamaica, xvi. 377, Hunter — see Waters, Mineral and Medicinal. Springs, (mechanics), theory of the action of, ix. 18, Jurin Sproule, G., eclipses of Jupiter's satel., at Gaspee, xiii. 526 Spry, Edw., m. d., case of" a morbid eye, x. 5b 1 — case of a man who swallowed melted lead, x. 673 — exper. on the effects of melted lead poured down the throat, x. 674 — an improved portable barometer, xii. 201 — cure of palsy, and locked jaw, by electricity, xii. 391 Square, see Quadrature. Squilla aquae dulcis, account of,vii. 660, Richardson Squinting, see Sight. Squire, Rev. S., speech recov. by means of a dream, ix. 465 Squirrel,of the sciurus volans, Linn., vii. 588, Klein lemur volans, Linn., ibid, Same — the flying squirrel of America, viii. 104, Dale — two species of, from Hudson's Bay, xiii. 330, . . Forster Stack, T., m. d., account of Huxham de Aere, cmc. viii. 265 — of a woman of 68, who gave suck, viii. 327 Stackhouse, Hugh, account of the death-watch, vii. 49 Stackhouse, Rev.T., bills of mortality, and tumuli, of Bridg- north, viii. 581 Stafford, Rich., on the nat. hist, of the Bermudas, i. 283 Stag, longevity and medical virtues of, i. 281 ; denied, 281, 282, Notes — anatomy of the Canadian, iii. 392 — account of a sort of, in Virginia, viii. 103, Dale Stalactites, remarkable specimen of, ix. 87, Huxham Stamp, an antique, and of Roman stamps, viii. 248, Mortimer Stanhope, Earl, method of secur. buildings from fire, xiv. 447 — on the roots of equations, xv. 86 — remarks on effects of a thunder-storm in Scotland, xvi. 2l6 Stannyan, Capt, observs. of the solar spots, 1703, v. 166 Stars (fixed) translation of Ulug Beig's catalogue, i. 52 — occultation of some, by the moon, ii. 663, .... Hevelius — method of observing their parallax, iii. 562, . . . .Wallis — of their distance, iii. 632, Roberts — on the change in their latitudes, vi. 329, Halley — remarks on Cassini's essay of the parallax of, vi. 443, Same — infinity of the sphere of, vi. 456, Same — number, order, and light of, vi. 457, Same — new apparent motion discovered in, vii. 308, . . . Bradley — occupations of several by the moon, vii. 440, . . Carbone — cause of the appearance and disappearance of, vii. 519, Maupertuis — apparent motion of the, ix. 417, Bradley — on the mutations of the, xi. 432, Barker — probable parallax and magnitude, xii. 423, .... Michell Stars (fixed) cause of their twinkling, xii. 438, .... Same — on their parallax, xv. 196, Herschel — changes in the position and magnitudes of some fixed stars, xv. 397, Herschel — on their distance and magnitude, xv. 465, Michell — relative positions and magnitude, xv. 51 6, . . Wollaston — on their nature and construction, xvii. 478, . . Herschel — method of observing their changes, xvii. 712, ... . Same — plan of a catalogue of their comparative brightness, xvii. 725, j Same — rotation of, on their axes, xviii. 62, Same — correction of Flamsteed's catalogue, xviii. 177,. • . . Same — notes to his own catalogues, xviii. 179, 475, .... Same — diminution of their light when near a planet, xviii. 276, Same — see Nebuloe. Stars, a new one in the Swan's breast, i. 127, .... Hevelius Whale's neck, i. 142, 162, Bulliald Andromeda's girdle, ibid, . . Same another new one in the Swan, i. 528, 607,. . Hevelius — earlier discovery of the same at Dijon, i. 530, 608 — of the appearance and disappearance of, i. 609 — latitude and distance of the Pleiades, i. 673, . . Flamsteed — new ones in the Whale's neck, and the Swan, ii. 384, Hevelius — occultation of t in the Bull, vi. 92, Bianchini — new in the Swan's neck, vi. 153, . Kirch — hist, of new stars, and of that in the Swan's neck, vi. 196 — in Gemini, occultation of by Jupiter, vi. 271 — in Scorpio, transit of Mars over, ibid — occultation of Corleonis by the moon, ix. 336,. . . . Bevis — declination of some southern stars, ix. 664, Condamine — eclipse, by the moon, of /3 Capricorni, xi. 408, . . Short of a Virginis, x. 618, .... Porter — occultation of Spica trjp by the moon, xii. 220, Liesganig Virginis, xii. 221, Same — £Tauri by the moon, xiii. 59, Ludlam »•• ■ » and y Tauri by the moon, xiii. 6"46,Lexel — of a periodical star in Collo Ceti, xiv. 689, ..Herschel — Coma Berenices, a nebula observed in, xv. 37, . . Pigot — discovery of some double stars, xv. 38, Pigott — a catalogue of double stars, xv. 213, Herschel — observations of the variation of light in Algol, xv. 456, Goodricke ■ xv. 460, . . Englefield ibid, Palitch — a catalogue of double stars, xv. 642, Herschel — variation in the brightness of » Antinoi, xv. 649,. . Pigott ,8 Lyrae, xv. 653, Goodricke -- Greenwich, xii. 588, Maskelyne Oxford, &c. xii. 625, Hornsby — — — xii. 6\o, Horsley . Kew, xii. 631, Bevis .1 Spital-square, xii. 633, Canton Leicester, xii. 641, Ludlarn - at the North Cape, xii. 645, .... Bayley Leeds, xii. 648, Smeaton — various observations in France, xii. 663, . . Lalande, &c. at Stockholm, xii. 67 1, Ferner East Dereham, xii. 673 Wollaston — July 1767, at George's Island, xiii. 276, Wallis — Oct. 1772, at Chiselhurst, xiii. 382, Wollaston — June 1778, in London, xiv. 460, Wales ■ at Leicester, xiv. 46l, Ludlam — total eclipse June 1778, at sea, xiv. 4p5, Ulloa at various places, xvi. 529, Piazzi — appearances during an eclipse 17.93, xvii. 351, Herschel — observ. of the eclipse of 1793, xvii. 422, .... Schroeter Sun (parallax) distance from the earth, i. 53, ii. 90, Flamsteed — method of determining the parallax, vi. 242, . . Halley — horizontal parallax of, x. 455, Delisle — parallax determined, xi. 649, xii. 22, Short — distance from the earth, xi. 677, Daval — horizontal parallax of, xi. 717, Short — parallax, from various astronom. observs., xii.44,Hornsby — from observ. of a transit of Venus in 1761, xii. 1 \7, Pingre xii. 157, • . Short — computation of the distance from the earth, xii. 411, Horsley ; inaccuracy in the computation, xii. 415,Note — new method of determining the parallax, xii. 520,Planman — distance computed by gravity, xii. 619, Horsley — parallax from the transit of Venus, I76'9,xiii.220, Hornsby ■ xiii. 284, . . Euler Sun (spots in the) spots discovered by Cassini, i. 6l5 by Paris Royal academy, i. 631, 656 i. 648, Hook — observed at Hamburgh, i. 659 — observations of (1 676) ii. 331, ... . Flamsteed and Halley — the same, ii. 332, Cassini — observations, l6'84, & return predicted, iii. 20, Flamsteed — observations of June, 1703, v. 78, Gray ; 79> • • Derham — observations of June and July, 1703, v. 166, Stannyan — observations of, from 1703 to 171 1, v. 622, ..Derham — remarks on the nature of, v. 625, Crabtree — observations on, and inquiry into the cause of, xiii. 482 ; xv. 366, Wilson — opinion respecting them, xiii. 529, Marshall — remarks on the nature of, xiii. 533, Wollaston Sun-fish [diodon mola] description of, viii. 402, . . Barlow Sun-plant, [crotalaria junceaj of Hindostan, culture and uses of, xiii. 507, Ironsides Superville, Daniel de, m. d., cause of monsters, viii. 385 Supple, Richard, eruption of Vesuvius, 1751, x. 220 Surd roots, method of approximation in extract., iv. 1. Wallis Surfaces, on the division of, xiii. 73, Glenie Surgery, 4 extraordinary cases, iv. 504, Greenhill — see Particular Cases. — see also Machines, and Instruments (Surgical.) Surveying, errors in, from magnetic var. iv. 180, Molyneux — a new plotting table, viii. 502, Beighton Survivorships, on the probabilities of, xvi. 475, 529, Morgan — see Reversions, Sus iEthiopicus, on the teeth of, xviii. 524, Home Sutton's ventilators for ships, account of, viii. 553, Meed — remarks on, viii. 56*0, .,,.... ,,,,,,... Watson Swallows, Hevelius respecting them, 1. 126, i. 127, Scheffer — martins, &c, on the migration of, xi. 425, . . Collinson — taken in a dormant state from holes in the cliffs of the Rhine, xi. 705, Achard — the swallow from Hudson's Bay, xiii. 342, .... Forster — on the torpidity of, xiii. 660, Cornish Swammerdam, John, m. c, biograph. memoir of, i. 190, 442, Notes — on respiration i. 190 — of animals with lungs but no pulmonary artery, ii. 69 — unusual rupture of the mesentery, ii. 199 Swan, anatomical description of the, i. 381 Swartz, Olof. m. d., description of the plant chloranthus, xvi 302 Sweat, cure by sweating in hot turf, vii. 37, Dudley — description of the sweating-rooms of the Indians, vii. 38, Same — see Hypocaust. Sweden, catalogue of minerals from, vi. 49, Petiver Sweets, observations on sweet tastes, iv. 676, Floyer Swelling, see Tumours. Swift, William, electrical experiments, xiv. 314, 571 Swimming, under water, machine for, ii. 500, .... Borelli Swinden, H. Van, of the thermometer ac Francker, Jan 1767, 1768, 1770, xiii. 386 Swinton, Rev. John, d. d., the Palmyrene alphabet, x. 522 — a Parthian coin with characters resembling the Palmy- rene, x. 706 — Parthian coin with Greek and Parthian legend, xi. 109 — Phoenician numerals used at Sidon, xi. 291 — an inedited Parthian coin, xi. 484 — a Samnite Etruscan coin, xi. 500 — an inedited Samnite Denarius, xi. 521 — of an anthelion observed near Oxford, xi. 532, — of a meteor seen at Oxford, xi. 534 — explanation of a Punic inscription at Malta, xii. 17, 172 — observations on two Etruscan coins, xii. 113 — a remarkable meteor seen at Oxford, xii. 162 — on the Abbe Bartlemi's memoire respecting the Phoeni- cian alphabet, xii. 17 1 — of a Palmyrene inscription at Teive, xii. 274 — a coin of Crispina with Greek legend, xii. 275 — explanation of two Parthian coins, ii. 357 — observation of a meteor at Oxford, 1766, xii. 401 — large swarms of gnats at Oxford, 1766, xii, 403 — legend of a Phoenician medal explained, xii. 441 — explanation of a Punic coin of Gozo, xii. 56*1 ■ an Etruscan coin of Paestum, xii. 562 denarius of the Veturian family, ibid, &xiii. 370 Punic coin of Gozo, xii. 563 — an inedited Punic coin, ibid — two aurorae boreales at Oxford, 1769, xii. 66 1 — explanation of two Samnite denarii, xii. 677 — of a Greek coin of Philistis, Queen of Syracuse, xiii. 18 — a remarkable meteor seen at Oxford, 1769, xiii. 88 — explanation of a Punic or Phoenician coin, xiii. 101 — — — — -— two Etruscan weights or coins, ibid two biculo-Punic coins, xiii. 103J — observations on 5 Persian coins, xiii. 169 — a sub-aerated Plaetorian Denarius, xiii. 283 — explanation of a monogram on a quinarius, xiii. 530 Switzerland, of the ice-mountains of, i. 365, ii.123, Muraltus — of the same, v. 488, Burnet Sword-fish, some account of a species of, i. 46, .... Note — of an animal that sticks to the, ii. 119 Sycamore, see Sap, Sydenham, Dr. his merit as a physician, i. 69 Sylvius, F. de la Boe, biographical account of, i. 289, Note 102 TAY INDEX. TEN Symmer, Rob., experts, and observa. on electricity, xi. 405 Sympson, Thos., description of a Roman hypocaust, viii. 532 Syrup, description of Orrae's pectoral syrup, viii. 505 T Tabashir, of the Arabian drug so called, xii. 369, Canning xvi. 653, . . Russel — chemical experiments on it, xvii. 101, Marie Taberg, a mountain of iron ore at, x. 564, .... Ascanius Tables, Halley's and Dupre's mortuary tables compared, x. 383^ Kersseboom — on those by Halley, and others, xi. 523,^ T. W. of the prices of provisions, &c. from the conquest, with the mean depreciat. of money, xviii. 309, Shuckburgh Tabor, John, tessellated pavement, &c. at Bath, &c, vi. 273 — situation of the ancient city Anderida, vi. 351 Tacquet, R. P. Andrew, biographical notice of, i. 314, Note — substance of his book, Opera Mathematica, ibid Tadmor, see Palmyra. Tadpoles, on the production of, iii. 456, Waller — circulation of the blood, iv. 464, Leuwenboek Taiaca, see Musk Hog. Talc, of talc rocks in Hungary, i 456, Brown Tali Lusorii, of the ancients, account of, xi. 85, .... Nixon Tangents, on drawing them to any curve, ii. 38, 74, Sluse — analogy of logarith. tangents to the merid., iv. 68, Halley — of curves deduced from the maxima and minima, v. 17, Ditton — analogy of logarith. tangents to the merid. x. 89, Robertson Tanning, directions and an engine for, ii. 136, 137, Howard — modern improvements in, ibid, Note — improved method of, xiv. 304, Macbride Tapestry, of Le Blon's method of printing in imitation of painting, and of weaving tapestry, vii. 477, Mortimer Tapping, an improved method for ascites, ix. 5, 40, Warrick — method of injecting liquors into the abdomen, ix. 8, Hales — on injecting claret after, x. 676, Warrick — see Ascites, Dropsy. Tar, method of making near Marseilles, iv. 303 Bent Tarantula, remarks on the bite of the, i. 241 — enquiries concerning, i. 649, Lister — disorders pretend, to arise from the bite, i. 719, Cornelio — inoffensiveness of the bite of, xiii. 47, Cirillo Tartar, volatilization of the salt of, ii. 54, Becke Tartary, East, Emperor of China's journey to, iii. 278, 282 Tasman, Abel Jansen, journal of discovery, ii. 542 Taste, on the organ of, i. 1 36, Bellini — class of sweet-tasted plants, iv. 677, Floyer Taube, H. W., rapture of the navel, ix. 41 Taurus, (star,) see Stars. Tavernier, M., biographical notice of, ii. 423, Note — observations in parts of Asia, ii. 343, 355 Taylor, Brooke, biographical account of, v. 706, .... Note — shape of the ascent of water between planes, ibid. — to find the centre of oscillation, vi. 7 — of the motion of a tense string, vi. 14 — experiment of magnetical attraction, vi. 168 — extraction of numeral roots of equations, vi. 299 — method of computing logarithms, vi. 304 — solution of Leibnitz' problem, vi. 308 — apology against John Bernoulli on account of mathema- tical inventions, vi. 397 — parabolic motion of projectiles, vi. 510 — magnetical experiments, vi. 528 — on expansion of liquor In the thermometer, vi. 641 Taylor, John, ll. d., Roman inscrip. at Rochester, ix. 295 — Roman inscriptions at Netherby, xi. 708 Taylor, Silas, the killing of rattle- snakes in Virginia, i. 16 Taylor, Robert, uncommon hail-storm in Hertford, iv. 172 — case of conjoined twins, v. 333 Taylor, W., irregularity of the tide in the Thames, x. 694 Tea, on the quality and virtues of, iii. 120, Pechlin Tears, microscopical observations on, ii. 151, Leuwenboek Teeth, cut at a very advanced age, i. 141 , Colpresse — microscopical observ. on, ii. 438 ; iii. 36, 503; iv. 0O9, Leuwenhoek — cut at 80 years of age, vi. 72, Slare — of the sea-wolf and chaetodon nigricans, xv. 540, Andre — renewal of teeth of cartilaginous fishes, xv. 54-2, . . Same — mode of dentition of elephants, xviii. 509, Corse — structure of the teeth of gramin. animals, xviii.519,Home — see Bones (Fossil.) Telescopes, table of proportionate apertures, i. 22, . . Auzout — improvement of, i. 36, .... Hevelius, Huygens, Du Son — measurement of distances from one station, i. 43, Auzout — on the theory of the, i. 666, Cherubin — invention and use of the reflecting, i. 69 1, 695, 703 ; letter of M. Huygens respecting it, 694, Newton — table of apertures, lengths, &c. of, i. 704, Same — answer to objections against his reflecting, i. 705, Same — a reflecting, by M. Cassegrain, i. 71 1 ; remarks on it, 712, Newton — of telescopic sights, ii. 130, Hevelius — for observations by day or night, iii. 336, .... Molyneux — use of cross hairs in, vi. 494, Halley — account of a catadioptric, vi. 646, Hadley — description and use of an equatorial, ix. 695, Short — improvement of the refracting, x. 341, Dollond — improvement in the cross wires of, xiii. 507,. . . . Wilson — on making and polishing the metals of reflecting teles- copes, xiv. 157, • Mudge — description of an iconantidiptic, xiv. 501, Jeaurat — magnifying powers of Herschel's, xv. 234, .... Herschel — new eye-glasses for, xv. 350, Ramsden — a new system of wires for, xvi. 7, Wollaston — description of his 40 feet reflector, xvii. 593, . . Herschel — on the power of, to penetrate into space, xviii. 580, Same — method of viewing the sun advantageously with power- ful telescopes, xviii. 683, Same — see Object Glasses, Optic Glasses. Temperature, of climate, cold most conducive to health, iii. 96, Lister — influence of cold on the health, xviii. 1, .... Heberden Tempers, conjectured by modulations of voice, ii. 44-1, Ent Tempest, Wm., agitation of the waters, x. 649, Kent Tempests, see Storms. Temple, a Pagan temple at Cannara, v. 501, Stuart — see Antiquities. Temple, Hon. Hy., an earthq at Naples, 1732, viii. 401 Templeman, Peter, m. d., polypus at the heart ; scirrhous tumour in the uterus, ix. 274 Templer, John, two hurricanes in Northamptonshire, i. 593 — remarks on glow-worms, i. 603, 660 — structure of the lungs, ii. 3 — training of vines over the roof of a house, ii. 60 — motion of the hearts of urchins, cut out, ii. 6l — to catch fish by tickling, ii. 78 Tendon, of Achilles, cured after a complete division, iv. 376, Cow per — of the thumb, torn away with the joint, xi. 235, Home — see Muscles. Teneriffe, journey to the peak of, vi. 177, Edens x. 230, Heberden Tenison, Rev. E., on the husbandry of canary-seed, vi. 18 Tennant, Smithson, decomposition of fixed air, xvii. 50 — on the nature of the diamond, xviii. 97 THE INDEX. THU 103 Tennant, Smithson, action of nitre on gold and platina, xviii. 139 — of the sorts of lime used in agriculture, xviii. 54.9 Tenon, William, machine for raising water, iii. 244 Tentzel, W. Ernest, an elephant's bones dug up at Tonne, iv. 218 Tercera, a volcanic island raised near, vi. 584, .... Forster Teredo Navalis, description of, viii- 378, Baster Tern, [Sterna] from Hudson's Bay, xiii. 348, .... Forster Ternata, of the burning mountain at, iv. 13 Termites, nat. hist, and economy of the, xv. 60, Smeathman Terra Ponderosa, see Barytes. Tessellated work at Leicester, v. 643, Carte pavement, &c. at Bath, &c. vi. 273, Tabor at Grantham, vii. 227, Stukeley Tessera, account of a Roman, in Bedfordshire, ix. 484, Ward Testicles, remarks on, i. 241, 271, De Graaf and Van Horn ■ i. 302, Bonglarus — experiments on, i. 391, King; 392, De Graaf; 393, Clark — of a horse, remarks on, i. 590, Malpighi — of the scarabams nasicornis, like the human, ii. 69 — examination of the testicle of a rat, iii. 481, Leuwenhoek — see Generation. Test liquor, for acids and alkalis, xv. 605, Watt Testimony, on the degrees of credibility of human, iv. 438 Tetanus, effect of electricity applied to, xi. 679, • • Watson Tetricus, hist, of the emperor, from medals, x. 349-.Boze Tetrodon, electricus, description of the, xvi, 134, Paterson Tetters, cured by plumb- tree gum and vinegar, i. 304 Thales, on the year of the eclipse foretold by, x. 310, Costard — x. 380,Stukely Thames, see Tides. Thermometer, on ascertaining the divisions of, iii. 505 , Halley — height of the spirit near the Cape, iv. 500, Cunninghame — scale of the different degrees of heat, iv. 572 — of a new one, iv. 616, Geoffroy — on expansion of liquors in, vi. 641, Taylor — degrees of heat of boiling liquors, vii. 1 Fahrenheit — construction of quicksilver thermometers, viii. 66,Delisle — variation of, within doors and without, ix. 372,. . Miles — a new metalline ; construction of thermometers, &c. ix. 397, 460, Mortimer — a new metalline, ix. 459, Johnson — on the construction, &c. of, ix. 6l6, . . .'Miles — agreement of, at London and Tooting, ix. 686, . . Same — observations on the cold of the winter of 1754, x. 454, Arderon — for shewing the greatest degree of heat and of cold during the observer's absence, xi. 138, Cavendish — a new metalline, xi. 491, Fitzgerald — to ascertain the decrease of heat by elevation, xii. 218, Heberden — effect of painting the bulb black, xiii. 371,. . . . Watson — descrip. of the thermoms. of the r. s., xiv. 49, Cavendish — report on the use of xiv. 258, Committee of r. s. — experiments with, xiv. 740, xv. 157, Cavallo — description of a thermometrical barometer, xv. 1 64, Same — an improvement in the, xv. 195,. Six — for measur. high deg. of heat, xv. 278, 570, Wedgwood — experts, on the conducting power of air, &c. xvi. 108, Rumford — for experiments on the conducting power of substances, xvii. 135, , Same Thermometer (tables and observations) i. 415, Beale i. 416, ....Wains — observations in 1723, vii. 2, Cruquius — agreement of, at London and Tooting, ix. 686, . . Miles — journal kept at Brabant, x. 126, , Stedman Thermometer (tables and observations) comparison of ob- servations in Siberia, x. 344, Watson — state of, at the Hague, Jan. 9, 1757, xi. 97, . . Trembley — in London, July, 1757, xi. 176, Huxham. — January, 1740 and 1768, compared, xii. 507, .. — Bevis — remarks on the same subject, xii. 50S, , Short — at Allahabad, and on a voyage from the East Indies to England, xiii. 632, Barker — see Heat, Cold, Weather, Meteorological Observations. Thermoscope, see Thermometer. Thibet, account of the kingdom of, xiv. 188, .... Stewart — letter from the Tayshoo Lama to Mr. Hastings, xiv. 196 Same — vegetable and mineral productions and diseases of, xvi. 539, Saunders Thigh, see Os femoris, Aneurism, Luxation, &c. Thomlinson,Rev.T., agitat. of the waters at Rochford,x,65l — effects of a hurricane in Cumberland, xi. 112 Thompson, Benjamin, see Rumford, Count. Thoracic duct, communicating with the emulgent vein, i. 163, 736, Pecquet; annotations on, 736, Needham — case of the ossification of, xiv. 739, -.. . . Cheston Thorax, experiments on injecting liquor into, iv. 271, Mus- grave ; how absorbed and discharged, 272, .... Note — a bony substance in the cavity of, vii. 159, Rutty — perforated, on respiration with, viii. 68, .... Houstoun Thoresby, Ralph, of a Roman pottery near Leeds, iv. Ill — two Roman altars in north of England, iv. 198 — some Roman antiquities in Yorkshire, iv. 215 — on the fabric of a Roman shield, iv. 279 — a young man killed by thunder and lightning, iv. — cures by Mr. Greatrix with stroking, iv. 427 — accident by thunder and lightning at Leeds, iv. 500 — of several natural curiosities in his museum, iv. 644 — Roman coins, &c, in Lincolnshire, iv. 675 — vestiges of a Roman town near Leeds, iv. 718 — of an earthquake in north of England, v. 104 — of balls voided by stool, v. 135 — of a Roman coffin found near York, v. 196 — of the pewter money coined by James II, v. 199 — a large Swedish coin, or medal, &c, v. 202 I — description of some Norman coins, v. 253 — of a Roman inscription at York, v. 263 ! — Roman coins found in Yorkshire, ibid — of a ball voided by stool, and of calculi, v. 270 — of Roman inscriptions at York, v. 280 I — eruption of waters from a rock in Yorkshire, v. 293 — Roman coins found in Yorkshire, v. 430 — Roman antiquities, account of a storm, v. 480 — Roman antiquities in Yorkshire, v. 487 — brass weapons found in Yorkshire, v. 510 — lunar rainbow, and storm of thunder, &c„ v. 642 — account of a meteor, May, 17 10, v. 6*43 — of a hail-storm in Yorkshire, v. 699 — large stones voided per urethram, v. 706 — effects of violent rain in Yorkshire, vi. 585 — Roman antiquities in Lincolnshire, vi. 660 Thornhill, Wm., successful use of agaric as a styptic, x. 621 Thornton, Rich., rule for finding Easter, v. 202 Thornycroft, E., doctrine of alternations and combin., v. 210 Thorpe, John, m. 0., of worms in the heads of sheep, v. 180 — hydatids in the abdomen, vi. 556 Thorpe, John, chesnut trees indigenous in England, xiii. 116 Threapland, Sam., m.d., of stones voided by stool, iii. 146 Throat, efficacy of black currants for a sore, viii. 479* Baker — cure of the trachea cut through, xi. 623, .... Huxham Thrush, two species of, from Hudson's Bay, xiii. 338, Forster Thumb, the first joint and tendon torn away, xi. 235, Home 104 TID INDEX. TO B Thunberg, C. P., m.t>., descr. of the bread-fruit tree, xiv. 572 — journal of a residence at Japan, xiv. 634 Thunder, cause of, x. 287 Eeles Thunder and lightning, an accident by, at Oxford, i. 74; effects on the interior and exterior of a body deceased by it, ibid, Wallis ->— accident by, in Hampshire, i. 84 — effect of a thunder-clap at Stralsund, i. 526 — effect of, on wheat and rye at Dantzick, ii. 8.9, • • Kirkby — extraordinary effect of, near Aberdeen, iv. 109, Garden — on the production of thunder, lightning, and hail, iv. 197, 212, Wallis — effect of, on a ship, iv. 222, Mawgridge — storm of, at Everdon, iv. 226, Wallis — of a young man killed by, iv. 351, . . Thoresby — an accident by, at Leeds, iv. 500, Same — strange effects of a storm in Ireland, v. 39 >, Molyneux — effects of a storm at Ipswich, v. 431, Bridgman — same storm at Colchester, v. 432, Nelson — storm at Leeds, Nov. 1675, v. 642, Thoresby — storm in Devonshire, v. 702, Chamberlayne — of a person killed by, vii. 153, Beard * — effects of a storm in Wales, vii. 437, Davies ■ — effects of, on trees, viii. 360, Clark June 1748, ix. 528, Miles ■ a storm in Devonshire, x. 223, Palmer — analogy of electricity with, x. 289, Mazeas — effects of a storm in Cornwall, x. 335, Borlase on a hulk at Plymouth, x. 560, .... Huxham • church in London, x. 629, Brander i America, x. 633, .... Franklin at Dorking, x. 634, Child a storm in Cornwall, xi. 86, .... Dyer & Milles — — — • on a church and steeple, xi. 113, . . Smeaton " a storm at Norwich, xi. 327, Cooper Rickmansworth, xi. 392, Whitfield Tides, time of the highest near Bristol, i. 266, 290, Sturmy — tide table for quarters of hours, i. 291, Same — on the doctrine of tides, i. 5l6, Childreyj Wallis' s reply to, 520 — irregular flux and reflux of the Euripns, i. 592, . . Babin — about the Orcades, ii. 106, Moray — on a corrected tide table, ii. 555, Flamsteed — another tide table, iii. 3, Same — at Cabo Corso, on the African Coast, iii. 32, Heathcot — at the bar Tonquin, iii. 67, iv. 148, Halley — course of at Dublin, iii. 333, Molyneux — time of high water on the French coasts, iii. 337 — analogy between the motion of disease and tides, iii. 551, Paschal — beans from Jamaica floated to Scotland, iv. 103, . . Sloane — on the true theoiy of, iv. 142, Halley — a high tide in the Thames, 1726, vii. J 33 3 1736, viii. 59, Jones — observations of tides in the Thames, ibid, .... Saumarez — state of, in Orkney, ix. 667, Mackenzie — in the river Forth, irregular, x. 31, Wright — irregularities observed at Chatham, x. 693, .... Godden Sheerness, ibid, Monarty Woolwich, x 694, .... Taylor — two violent storms in Cornwall, xi. 622, Borlase — effects on a church in Essex, xii. 126, Heberden — of the damage to St. Bride's steeple, 1764,xii. 131, Watson xii. 140, Delaval — effects of the same storm in Essex-st, xii. 144, Laurence at Martinique, xii. 149, Wilson — several cases of its effects on ships, xii. 157, .... Veicht — effects of, in Pembroke college, 1765, xii. 254, Griffith on Buckland Brewer church, xii. 6l0, Paxton St. Keverne church, xiii. 98, Williams Tottenham-court road chapel, xiii. 307, Henley at Leeds, xiii. 420, Kirkshaw Steeple Ashton and Holt, xiii. 435, . King on Lord Tilney's house at Naples, xiii. 455, Hamilton — fatal effects of a storm in Scotland, xvi. 186, . . Brydone — remarks on the storm in Scotland, xvi. 2 1 6, Earl Stanhope Thyme, on the camphor of, vii. 93, 631, Neuman Tiberiades, analysis of the hot spring near, viii. 556, . . Perry Ticunas, experts, with the poison of, x. 144,. . . . Herissant xiv. 641, .... Fontana Tides, in the West Isles of Scotland, extraor , i. 21, Moray — hypothesis on the doctrine of, i. 89, Wallis 5 reply to some animadversions on it, i. 101, Same; Childrey's animadversions, 51 6; Walliss reply, 520 — inquiries concerning, i. 112, Wallis ; i. 113, .. . Moray — apparatus for observing the flowing of, i. 114, Same — tables proposed for the observation of, i. 118, Same — at the Bermudas, i. 206, Norwood ; 283, Stafford — observation of, at Plymouth, i. 227, Colepresse — cause of variety of the ann . tides of England, i. 239, Wallis — plan for calcu. ; and on the tides at London, i. 240, Philips — in the straits of Gibraltar, observations, xi. 607, . . More — St. Helena, observations of, xi. 647, Maskelyne — an unusual tide at Bristol 1764, xii. 109, Tucker — state of, at Suez, xii. 281, '. Montague - at Otaheite, xiii. 177, Green and Cook — observations of, in the South Sea, xiii. 323, xiv. 72, Same — account of the tides in the Adriatic, xiv. 130, . Toaldo — at Naples, xvii. 319, . . Blagden — see Sea, Currents. Timber, proper season for felling, iii. 422, Plott — differ, of, felled at different seasons, iii. 672, Leuwenhoek Time, rectified ace. of, by a luni-solar year,, ii. 497, Wood — to find the hour of the night at sea, ix. 664, Condamine by equal altitudes, xiii. 734, Aubert — method of comput. the equation of, xii. 163, Maskelyne — see Clock, Watch. Timoni, Emanuel, biographical account of, vi. 88, . . Note — account of the plague at Constantinople, vi. 450 — practice of inoculation at Constantinople, vi. 88, vii. 646 Tin, description of the Cornish mines, i. 565 ; art of digging up the ore, and instruments for, i. 568 ; manner of dressing tin, 571 ; of blowing it, 573 — account of the Cornish mines, ii. 424 Merret - vii. 249 Nicholls — method of making tin-plates, vii. 304, Rutty — of the mines of Schlachtenwald, ix. 690,. . . . Mounsey — specimens of native tin, xii. 278, 359, 597, .... Borlase — its effect on gold when mixed, xv. 622, Alchorne Tin-foil, detonation produced, by a contact with nitrous salt, xiii. 404, Higgins Tincal, a production of Thibet, account of, xvi. 54 8, Saunders Tinctures, to give various tinct. to water, iv. 243, Southwell — effects of the opuntia and of indigo in colouring the juices of living animals, xi. 137, Baker — accidental tincture given to a stone, iii. 273, .... Reisel Tissot, Andrew, m. d., biograph. notice of, xii 20S, Note — observations on the disease called ergot, ibid Titmouse [parus] two species from Hudson's Bay, xiii. 342, Forster Tithimalus hibernicus, see Mackenhoy. Toads, noxious quality of the fluid of, i. 147, Note Toad-stone, analysis of the, xv. 293, Withering Toaldo, Abbe Jos., of the tides in the Adriatic, xiv. 130 Tobacco, culture of in Ceylon, iv. 667, Strachaa TOX INDEX. TRE 105 Todd, Hugh, d. d., of a salt spring near Durham, iii. 78 — antiquities at Corbridge, Northumberland, v. 632 Tokay, see Wine. Toledo, Alvarez de, of an earthquake at Peru, 1687, iii- 625 Tommagon, Porbo Nata, effects of an earthquake, 1699, °n the mountains of Batavia, iv. 502 Tones, on discovering tempers from the voice, ii. 441, Ent Tonge, Ezekiel, m. r>., on vegetation, and sap, i. 304, 317; additional remarks, 332, 423 — on the bleeding of walnuts, i. 441 — the bleeding of trees used as a substitute for the baro- meter, i. 559 — method of ordering of birch-water, i. 560 — on retarding the ascent of sap, i. 56*0 — inquiries respecting the running of sap, i. 56 1 Tongue, observations on it; as the organ of taste, i. 172, Malpighi — of a stone cut from under the, i. 7'7> Lister -- observations on the whiteness of, in fevers, v. 374, 449, Leuwenhoek — structure of the tongue, v. 425, Same — description of the woodpecker's tongue, vi. 264 — of a woman who could talk without, viii. 586, . . Baker — further particulars of the same case, ix. 375, Parsons — natural state and use of the, ix. 376, Same — of a person born with two tongues, ix. 484, . . Mortimer Tonquinese medicine, efficacy in the bite of a mad dog, ix. 89, Reid Top, account of Serson's horizontal, x. 229, Short Topaz, table of the specific gravities of, xviii. 377 Topping, M., measure of a base on the Coromandel coast, xvii. 146 Torkos, Justus John, of a double female, xi. 142 Torlese, John, account of a monstrous birth, xv. 180 Torpedo, anatomical description of the, ii. 485, Fiorentino — electrical powers of the, xiii. 469, Walsh — anatomical observations on, xiii. 478, Hunter — of torpedoes found near the British coasts, xiii. 570 Walsh — experiments on torpedoes, xiii. 575, Jngenhousz — expert, on the electricity of, xiv. 23 Cavendish Torques, agolden torquesfound in England, viii. 550, Mostyn Torres, Ignatius Jos., case of the heart inverted, viii. 508 Torricellian expert, trial of, on Snowden, iv. 174, . . Halley — on the monument, iv. 225, Derhatn — see Barometer. Tortoises, particulars of, at the Caribbees, Mexico, &c. i. 175, 295 — anatomy of the land tortoise, iii. 393 — weight at retiring into the ground, and at re-appearing in the spring, iii. 459, Ent — of the American land tortoise, iv. 324, Petiver — anat. of the heart of the land tortoise, v. 598, Bussiere — description of the testudo ferox, and coriacea, xiii. 144, Pennant Tourmalin, electrical experts, on the, xi. 396, Wilson — on the electric nature of the, xii. 343, Bergman Tournefort, M. Pitton, biograph. account of, iv. 323, Note Towns, Dr. T., on the nat. hist, of Barbadoes, ii. 228 Townly, Richard, biographical notice of, iii. 619, . , . Note — observations on Gascoigne's micrometer, i. i6"i — method of estimating the fall of rain, iii. 619 — quantity of rain in 1697, 1698, iv. 350 — fall of rain at Upminster 1703, 1704, v. 200 Toxicodendron [rhus] use of, in dyeing, x. 594-, . . Mazeas ! x. 596, . . . Miller — synonym of the China varnish-tree, xi. 46, Ellis — • remarks on the above paper of Mr. Ellis's, xi. 177. Miller — reply to Mr. Miller's observations, xi. 181, Ellis Trade winds, cause of the general, viii. 19, Hadley — see Monsoons. Tradescant, John, biographical account of, rix. 668, . . Note — account of his garden at Lambeth, ix. 668, .... Watson — some particulars respecting him, xiii. 385, .... Ducarel Transfusion of blood, Dr. Lower's method, i. 128, ..Boyle — considerations on its utility, i. 131, Same — trials of, proposed to Dr. Lower, i. 143, Same — an easy way without opening an artery, i. 158, . . King — an experiment on a mangy and sound dog, ibid, . . Coxe — experiments on, and a new method, i. 159, . . . .Denis two dogs at Paris, i. 167 — where and by whom it originated, i. 170, 185, Oldenburg; same opinion confirmed by Dr. Clarck, i. 248 ; a more remote antiquity asserted, 268 — trials of, and caution recommended, i. 183, Oldenburg; safe method proposed by Dr. Edm. King, i. 185 — experts, by Prof. Harwood, of Cambridge, i. 185, Note at Arundel house by Drs. Lower and King, i. 203 — relation of some trials in France, i. 204, Oldenburg — particular case of a phrensy cured by, i. 219, Denis; con- tinuation of, 258; remarks on, 2 o9, 263, notes; some further particulars of the case, 404 — its efficacy to cure diseases doubted, i. 248, .... Clarck — practised by Labavius, i. 268 — two experiments from the Giornale de Letterati, i. 300 Transits, see Venus, fyc. Transplanting, on the best season for, i. 581, Reed Travels, see Voyages and Travels. Tredway, R., ambergris thrown on shore at Jamaica, iv. 205 Trees, on reuniting the separated bark, i. 160, Merret — connexion of parts of a tree with the fruit, i. 334, Beale — found under ground in Lincolnshire, i. 551 — texture of, ii. 312, Leuwenhoek, Grew — experiments on the growth of, iii. 363, Brotherton — description of several, native of India, iii. 519, 540 — dug up in Yorkshire, iv. 162, Richardson — of subter. trees and their cause, iv. 624, 645, De la Pryme near the Thames, v. 68 1, Derham — a sinking of, in the ground, vi. 348, Neve — of subterraneous trees in Cornwall, xi. 80, Borlase — comparative growth of several sorts, xi. 320 ; xviii. 100, Marsha m — of the indigenous in Britain, xii. 594, Barrington — on the annual growth of, xvi. 507, Barker — on the grafting of, xvii. 569, Knight — on the recovery of injured trees, xviii. 442, Barker — of subterra. trees on the east coast of England, xviii. 479, Correa de Serra — see Birch, Chesnut, Elm, Fraxinus sylvestris, Oak, Querctts coccifera, Walnut, Willow. — see Fruit-trees, Plants, Sap, Bark, Roots. Trembley, Abraham, biographical notice of, viii. 623, Note — experiments on the fresh- water polypus, ibid. — newly discovered species of polypi, ix. 75 — electric light from quicksilver, ix. 199 — observations of several sorts of polypi, ix. 377 — abstract of Bonnet's memoir on caterpillars, ix. 504 — earthquake of Dec, 9> 1755, at Geneva, x. 665 — of basal tes in Germany, x. 703 — account of Donati's essay towards a natural history of the Adriatic sea, x. 704 — earthquake at Cologn, Liege, &c, 1756, xi. 55 — of earthquakes in Germany and Italy, xi. 83 — remarks on the polypi of coral, ibid. Donati's opinion of inland fossil shells, &e. xi. 84 — state of the therm., at the Hague, Jan., 9, 1757, xi. 97 Trew, Chr. Jas., m. »., biog. account of, vii. 441, ..Note o 106' TUM INDEX. URE Trew, Chr. Jas, m. d., of the cereus peruvianus, vii. 441 Triangles, descrip. of, in and about circles, xiii. 65 l,Stedman — see Trigonometrical Survey. a Triewald, Martin, queries on the cause of cohesion, vu. 33o instantaneous freezing of water, vii. 466 rapid flowering of bulbous roots in water, ibid improvement in the diving bell, viii. 98 description of a new water bellows, viii. 192 vegetation of old melon-seeds, viii. 577 Trigonometrical survey, measurement of a base on Hounslow- Heath, xvi. 22, Roy — proposed method for determining the relative positions of Greenwich and Paris, xvi. 240, Same — completion of the survey, xvi. 649, Same — longitudes of Dunkirk and Paris, ascertained from the survey, xvii. 67, Dalby measurement of a base at Coromandel, xvii. 146, Topping — survey of Denmark, 1762, xvii. 353, Bugge — survey in England, 1792—1794, by Williams, Mudge, and Dalby, xvii. 6l3; 1795, 1796', xviii. 236, 1797— 1 799, 787, D. of Richmond Trigonometry, diagonal divisions, ii. 1 89, Wallis — spherical reduced to plane, x. 255, Blake an abridgment or simplification of, xi. 210,. . Murdock — calculations in spherical, abridged, xiii. 690, Lyons elements of the trigonometric functions of circular arcs xvii. 703, L'Huillier Trinidad, geological account of, xvi. 531, Anderson Tripe, Nicholas, body buried 80 years undecayed, x. 202 Tripoli, or Terra Tripolitana, remarks on, xi. 372, Hubner . ibid,. . Da Costa Tripos, see Antiquities. Trobe, Nich. de la, meteorological journals at Labradore, xiv. 597, xv. 87 Trochar, see Instruments (surgical). Trochitae and Entrochi, see Rock-plants. Trout, of a sort with crooked tails in Wales, xii. 421, Barrington — account of the gillaroo trout, xiii. 509, Same Truffles, found in Northamptonshire, iii. 554, . Robinson Trumpet, defects in the musical notes of, iii. 467, Roberts Trumpet (Speaking) invention and use of, i. 670, Moreland — improvement of Moreland's, ii. 445, Conyers Tuba Eustachiana, see Ear. Tubes, ascent of water in small tubes, v. 289, • • Hauksbee 1 capillary tubes, vi. 330, 432,Jurin — rotation of glass tubes before a fire, ix. 114, . . Wheeler Tubularia indivisa, account of the, vi. 73, Lhwyd Tucker, Josiah, n. v., biograph. notice of, xii. 109, Note — a remarkable tide at Bristol, 1764, ibid Tulips, rapid flowering of, in water, vii. 466, ..Triewald Tull's (Mr.) method of castrating fish, x. 554, ..Watson Tulpius, N., M. D., biograph notice of, ii. 152, .... Note — remarkable case of dropsy, ibid Tumour, of a strange one in the lower part of the belly, iv. 132, Giles — a scirrhous tumour in the breast, v. 237, Greenhill — of an ossified tumour in the neck, v. 285, .... Douglas — in the neck filled with hydatids, v. 332, Tyson — of a scirrhous tumour in a cystis, vi. 73, Russel — of an extraordinary wen in the cheek, vi. 319, • • Bowen . — a preternatural tumour with cloven spine, vi. 487, Rutty — extraordinary case of tumours, vii 97 > Atkinson — cases of, in the abdomen, vii. 277, Rutty — in the lumbar region of an infant, vii. 386, . . Huxham — glandular, in the pelvis, viii. 158, Cant well — extraordinary in the knee, viii. 294, Peirce ■ - - » ■ thigh, viii. 410, .... Malfalguerat Tumour, which rendered the bones soft, viii. 464, .... Pott — in the ovarium with hair, ix. 29, Haller — near the anus of an infant, containing the rudiments of an embryo, ix. 512, Huxham — extraction of, inside the bladder, x. 32, Warner — extraordinary, on the head, xi. 155, Parsons — a steatomatous, in the abdomen, xiii. 108, .... Henley — in the human placenta, xviii. 338, Clarke Tumuli, see Antiquities. Tunis, geographical description of, vii. 364, Shaw Tunstall, Marmaduke, observ. of lunar rainbows, xv. 353 Turberville, Daubeney, m. d , on diseases of the eye, iii. 81 — two cases of disordered eyes, iii. 109 — cure of worms voided with urine, ibid Turkey, inquiries for a description of, i. 132 — of several diseases, ii. 6l ; way of dressing leather, ii. 62 Turkey, (bird) natural history of the, xv. 32, .... Pennant — a bird between a turkey and pheasant, xi. 493, Edwards Turner, D., m. d., dissection of a body dead of ascites, iii. 606 — case of dropsy in the tunics of the uterus, iii. 607 — case of hydrophobia, iii. 608 — a worm voided through the urethra, vii. 125 Turnips, to make bread from, iii. 599, Dale — speedy vegetation of, vi. 404, Desaguliers Tumor, E., an earthquake in Lincolnshire, 1792, xvii. 220 Turpentine, method of making near Marseilles, iv. 302, Bent Turquoise, remarks on the, ix. 324, Mortimer Twins, see Monsters. Tycho Brahe, account of his observatory, iv. 525, . . Gordon Tyger cat, of the Cape, description of, xv. 1, Forster Tyson, Edward, m. d., biographical account of, ii.448, Note — anatomical observations, ibid — of double ureters ; andglandulae renales, ii. 450 — physiological observns. on hair, teeth, bones, &c, ii. 490 — dissection of a rattle-snake, ii. 56l — on the lumbricus latus (taenia solium) ii. 591 lumbricus teres, (ascaris lumbricoides) ii. 605 — a hairy production from the womb, ii. 648 — anatomy of the musk-hog, ii. 668 — dissection of the body of Mr. Smith, iii. 374 — lumbricus hydropicus ; hydatids a sort of worms, iii. 445 — of an infant's brain depressed into the vertebrae, iv. 16*4 — hemisphere of the brain sphacelated, and a stone in it, iv. l65 — anatomy of the opossum, iv. 248 — remarks on the carnivorous nature of man, iv. 552 — anatomical description of the callionymus lyra, v. l62 — a tumour in the neck filled with hydatids, v 332 — a species of chaetodon from the South sea, xiii. 136 U Ulcer, account of a verminous ulcer, iv. 498, . . Steenveldt — cure of sinuous ulcers in the arm, v. 378, Fawler — of an extremely large scirrhous ulcer, v. 435, Amyand Ulug Beigh, catalogue of fixed stars translated, i. 52 Ulloa, Ant. biographical account of, ix. 620, Note — solar and lunar eclipses, Madrid, ibid — of 1 he earthquake Nov. 1, 1775, at Cadiz, x. 662 — total solar eclipse June 1778, at sea, xiv. 495 Unicorn Fish, descrip. of theNarhwal, viii. 160, Steigerthal — the same described, viii. l6l, Hampe Universe, on the System of the, iv. 428, Huygens Urchin, motion of the heart of, when cut out, ii. 6l,Templer — of the sea-urchin of Carolina, v. 2(>9, Petiver Ureters, case of double to each kidney, ii. 450, .... Tyson — case of one grown up, ix. 87, Huxham Urethra, of two glands with excre. ducts in, iv.445,Cowper — figure of the, viii. 485, . . . : Le Cat — strictures and callosity of the, x. 222, Same VAR INDEX. VEN ior Urine, expts. for finding a new passage for, i. 550, Hauton — suppression of, cured by acids, iv. 9> • • • Baynard — on the passage of drink and urine, iv. 653, .... Morin — of several solid bodies voided by, v. 521, Yonge — case of a boy who never made water, vi. 45, Richardson — case of the suppression of in a woman, vii. 528, Amyand — disch. of bloody urine in the small-pox, viii. 708, Dodd — ■ case of a long suppression of, xi. 376, Dawson — remarkable case of suppression of, xi. 663, .... Lysons — cure of a suppression of, by puncturing the bladder by the anus, xiv. 113, Hamilton Urns, Roman urns near York, ii. 518, Lister — and monuments found in Ireland, vi. 63, Nevill — dug up in Norfolk, vi. 65, Le Neve Urtica Marina, see Actinia. Uterus, description of that of a cow, iii. 57, .... Malpighi — of a large sarcoma or excrescence, iv. 78, .... Connor — of a foetus lying outside of, iv. 110, Savard — case of a scirrhous, v. 287, Douglas — delineation of, at childbirth, v. 324, Same — of several extra-uterine foetuses, v. 521, Yonge — a scirrhous tumour in the, ix. 274, Tern pieman — case of a double uterus and vagina, xiii. 572, . . Purcell — see Fcetus. Uvea, see Eye. V. Vacuum, boiling of water, and spirits of wine in vacuo, ii. 272, Papin — firing of gunpowder, in, ibid, Same — experiment of the dissolution of iron in, iii. 373, Same — on the motion of pendulums in, v. 172, Derham — firing of gunpowder on hot iron in, v. 182, . . Ilauksbee — quality of air by firing gunpowder in, v. 183, .... Same — production of light from phosphorus in, v. 196, . . Same — experiment on the sound of a bell in, v. 202, .... Same — resilition of bodies in, v. 208, Same — descent of dust in, ibid, Same — experiment on the attrition of bodies in, v. 270, . . Same — sound not transmittable through, v. 499* Same ■ — experiment of an interspersed, vi. 321, 480, Desaguliers — experiments of freezing in, vii. 22, Fahrenheit ■ electricity in, x. 233, Watson experts, on animal fluids in the receiver, xiii. 537,. • Darwin — see Air-Pump, (experiments with) Vagina, a double vagina and uterus, xiii. 572 Purcell Vaillant, Sebast., m. d., biograph. account of, vi. 314, Note — account of the genus araliastrum, ibid Valentine, Basil, biographical account of, i. 596 .... Note Vallemont, M. de, account of an egg within an egg, iv. 183 Valletta, S., eruption of Vesuvius, 1707, vi. 12 Vallisneri, Antony, biographical notice of, v. 248, . . . Note Valsalva, Ant. Maria, m.d., biog. notice of, v. 220. . Note — treatise on the human ear, ibid — excretory duct from the renal gland, vii. 55 Valvasor, J. W., way to cast statues extremely thin, iii 347 — account of the Zirchnitzer sea, iii. 411 Vans, Robt., a butter-like substance falling in Ireland, iv. 78 Vanbrugh, G.R. obs. of the comet of 1737, Lisbon, viii 155 Vapour, drawn from the sea by the sun, iii. 387, . . Halley — circulation, return of to the sea, iii. 427, Same — clouds and rain accounted for, vii. 323, .... Desaguliers — conjectures on the rise of, viii. 584, Same — cause of the ascent of, x. 587, Eeles — on Mr. Eele's theory of the ascent of, xi. 124 . . Darwin — from intensely heated water, force of, xi. 458, . . Note — see Evaporation, Damps. Varelaz, Jos., disparition of Saturn's ring observed, xiii 509 Varenius, Bernard, biographical notice of, ii. 50, .... Note Varnish, manufacture and method of using the japan, iv.299 — several sorts of Chinese, 482, Sherard — poisonous effects of the Indian, iv. 608, Del Papa — of the varnish tree of China, x. 387, D'Incarville — on the species of the China varnish-tree, xi. 46, 181,Ellis — see Toxicodendron. Vassal, M., of a foetus in the fallopian tube, i. 358 Vassen, Berger, solar eclipse at Gottenburg, vii.-6l8 Vater, Abm., m.d., biographical account of, vi. 483, Note — case of a colon propendent from the abdomen, ibid. — stones voided bv drinking Pyrmont waters, vi. 656 — case of a partial sight of objects, vii. 44 — dissection of a body dead of calculous complaints, vii. 144 — case of a plica polonica, and the cause, vii. 462 — of the Mexican filtring stone, viii. 30 — remarkable cutaneous disease, viii. 59 — cure of a viper's bite by oil, viii. 265 Vaughan, H., m. d., poisonous quality of the oenanthe crocata, iv. 242 — bad effect of swallowing fruit-stones, iv. 710 Vautravers, M. de, earthquakes Nov., 1, Dec, 9> 1755, in Switzerland, x. 665 Veay, M., account of an extraord. hermaphrodite, iii. 356 Vegetables, anatomy, structure, &c. of, i. 060 ; ii. 255, Grew of, ii. 229, 483, Malpighi — veins of plants and their use, i. 668 j ii. 34, .... Lister — same subject, ii. 74, Wallis — remarks on the food of, iii. 365, Brotherton — propagation of plants, iii. 525, Leuwenhoek — nature and difference of the juices of, iv. 123,. . . . Lister — experiments on the food of, iv. 382, Woodward — similar virtues in same class of plants, iv. 4l6, . .Petiver — anatomical preparation of, vii. 436, Seba — description of vegetable balls, x. 280, Dixon — remarks on the byssus, x. 426, Boze, Watson — micros, observ. of the impregnation of, xii. 249, . . Stiles — experiments on the heat of, xiv. 278, Hunter — influence of, on animal life, xv. 319, Ingenhousz — observations on their irritability, xvi. 421, Smith — on the impregnation of, xvi. 424, Same — on the fecundation of, xviii. 504, Knight — see Plants, Trees, &c. Vegetables, (chemistry,) volatile salt from, ii. 124, ..Coxe — method of discovering the qualities of, ii. 485, .. Dodart Vegetable fly, description of the, xii. 15, Watson Vegetable lamb, see Agnus Scythicus. Vegetation, queries concerning, i. 285 ; answers to, 304 — remarks on, i. 304,317, Beale and Tonge ; additional remarks, 332, Tonge — to make trees, &c. grow to a great size, ii. 219 — experts, on, and the food of plants, iv. 382, Woodward — experiments and observations on, iv. 697 > De la Pryme — speedy vegetation of turnips, vi. 404, Desaguliers — remarkable instances of rapid, vii. 56, Dudley — of melon seeds 42 years old, viii. 577, Triewald 33 years old, ix. 100, Gale — of plants in moss, experiments on, ix. 468, Bonnet — generat. decomp. &c. of veget. bodies, ix. 605, Needham — vapours from mines not destructive of, xii. 342, Bowles — experiments and observations on, xiii. 399i • • • • Mustel — see Sap. Veicht, Robt. effect of lightning on ships, xii. 157 Veins, remarks on the extremities of, &c, iv. 680, Cowper — see particular veins, as Pulmonary Veins, Vena Cava, &c. — see also Transfusion, Injection, Blood. — for veins of plants, see Vegetables. Velocity, see Motion, (Force of Moving Bodies.) Vena cava, contraction of the, ix. 348, Haller 0 2 VEN INDEX. VE S Venereal disease, on the antiquity of, vi. 368, 467, 492, Beckett — remarkable case of, viii. 480, Huxham — of the grandgor at Edinburgh 1497, viii. 675, . . Macky — medical treatment of, in Siberia, x. 353, Gmelin — method of cure, in Thibet, xvi. 550, Saunders Ventilation, of use in distillations, x. 635, Hales — sweetens ill-tasted milk, and putrid water, x. 643, Same Ventilators, machine for ventilating rooms, viii. 12, 13, 15, Desaguliers — for ships, account of Mr. Sutton's, viii. 555, .... Mead viii. 560, . . Watson — account and utility of Hales's, x. 195, Ellis — used in Newgate, x. 318, Pringle — good effects of, in ships, x. 641, Hales — method of working by steam-engine, xi. 266, Fitzgerald Ventricle, see Heart, Venus (planet) spots discovered in, i. 217, Cassini; rota- tion of, 218, Note — conjunctions of with the sun, iii. 448 — error in Halley's predic. of the transit of 176l, vi. 249, Note — cause of its unusual brightness in 1761, vi. 250, Halley — meridian altitudes of, vii. 144, Laval — eclipsed by the moon, Bologna, vii. 265, .... Manfredi 1 Berlin, vii. 385, Kirch — conjunction with Mercury, 1737, viii. 470, Bevis — observation of a supposed satellite, viii. 476, .... Short — phaenomena of, ix. 226, Ferguson — conjunction with Mars, Pekin, x. 3, Hallerstein . Jupiter, , ibid, Same — occulted by the Moon, 1751, x. 1 74, Bevis x. 189, Bradley — eclipsed by the Moon, 1753, x. 408, . . Bevis and Short — transit, June, 1761, at Greenwich, xi. 552, Bliss — — — London, xi. 553, .... Short — London, xi. 555, .... Canton Chelsea, ibid, Dunn — — — — — — St. Helena, xi. 557, Maskelyne ■ — — Leskeard, xi. 559, • • Haydon — — — — — — — — Stockholm, xi. 560, Wargentin ■ ■ Sweden, xi. 56l, . . Various ' Paris, xi. 562, .... Lalande ■ ' ■ — in and near Paris, ibid, Ferner — — — Constantinople, xi. 563, Porter Upsal, xi. 564, .... Bergman — general deduction from the various observations of the same transit, xi. 564, Bliss — — ■ — Cajaneburg, ibid, . . . Planman • Madrid, xi. 571, . . . . Ximenes ' " Tobolsk, ibid, Chappe — ■■ Ley den, ibid, Lulofs Isle Bodrigues, xi. 595, Pingre Cape of Good Hope, xi. 595, Mason and Dixon Madras, xi. 596, Hirst — Bologna, xi. 597, Zanotti 7—— Calcutta, xi. 645, .... Magee — observations of the same transit in Europe compared with an observation made at the Cape, and the Sun's parallax thence deduced, xi. 640, xii. 22, Short — delineation of an expected transit, xi. 685, . . Ferguson — on the transit of June, 1761, xi. 695, Wargentin — obs. of transit, June, 1761, at Schwezinga, xii. 1 19,Mayer Newfoundland, xii. 156, Winthrop — proposals for observing the transit to take place in 1769, xii- 265, Hornsby — transit, June, 1761, at Upsal, xii. 289, Mallet Naples, xii. 554, Zannoni Venus, transit, June, 1761, at Malta, xii. 554,. . . . Zannoni June, 1769, at Greenwich, xii. 583, Maskelyne London, xii. 625, Horsfall Shirburn and Oxford, xii. 625, Hornsby Oxford, xii. 629, Horsley Kew, xii. 631, Bevis Spital square, xii. 632, . . Canton xii. 639, .... Hirst at Leicester, xii. 641, Ludlara in North America, xii. 643, Holland at island of Hammerfost, xii. 644, Dixon the North Cape, xii. 645, Bayley near Quebec, xii. 646, .... Wright at Gryphswald, xii. 648, .... Mayer in Philadelphia, xii. 649, American Committee Sweden, xii. 651,. .. .Wargentin. — Glasgow, xii. 652, Wilson near Edinburg, xii. 655, Lind Gibraltar, xii. 657, .... Jardine New England, xii. 608, xiii. 60, Winthrop several places in France, xii. 663, Lalande, &c. — — — — Cape Francois, ibid, ....Pingre — Martinique, xii. 664 at Paris, ibid, Messier in London, xii. 665, Aubert at Stockholm, xii. 67 1, .... Ferner East Dereham, xii. 672, Wollaston in Pennsylvania, xii 673, Biddle and Bayley Windsor-castle, xii. 676, . . Harris in Maryland, xii. 679, Leeds Hudson's Bay, xii. 682, Wales and Dymond — moment of contacts in the transits of I76l, I769,xiii.l4. Dunn — transit of 1769, observed at Dinapoor, xvi. 47, Degloss — various observations of the transit of I769, reduced to the meridian of Paris, xiii. 49, Pigott — transit of 1769, Ponoi, xiii. 6l, Mallett India, xiii. 78, Rose — — Strabane, xiii. 80, Masoq West Indies, xiii. 81, Pingre — effect of the aberration of light, on an observation of a transit xiii. 89, Price — transit of 1769, at California, xiii. 91, Doz xiii. 92, Chappe — at Otaheite, xiii. 175, Green and Cook — heliocentric longitude, &c., of, xvi. 621, Bugge — remarks on the atmosphere of, xvii. 232, .... Schroeter — rotation, atmosphere, &c, of, xvii. 330, Herschel — mountainous inequalities, atmosphere, &c. of, xvii. 506 Schroeter Venus (Antiquities) a statue of, discovered at Rome, xi.523 Mack inlay Venuti, Abbate de, antiquities found in Italy, xi. 372, 473 Verbiest, Emperor of China's journey to Eastern Tartary, 1682-3, iii. 278, 2S2 Verditer, method of making, ii. 455, Merret Vernati, Philabert, stone found in the head of a serpent an antidote for its bite, i. 38 — answers to queries respecting the East Indies, i. 307 — method of making cerusse,, ii. 421 Vernede, M., earthquakes at Maestricht 1756, xi. 8 Verney, Guichard, Jos.du, biograph. noticeof, ii. 432, Note — anatomical structure of the nose, ibid Vernon, F., travels through Istria, &c. to Smyrna, ii. 284 Verny, M., use and preparation of kermes for dyeing, i. 134 Versailles, account of the aqueduct at, iii. 167, 231 Vessels, delmeation of the seminal vessels, i. 250, Clarck — see Lymphatic Vessels, Lacteals, SfC, VI R INDEX VOY 109 Vesuvius, eruption of, 1694, iv. 78, Connor — 1707, vi. 12, Valetta ■ 1717, vi. 316, Berkeley 1730, vii. 555, Cyrillus 1737, viii. 36l ; analysis of some — articles thrown out, viii. 365, Prince of Cassano . 1737, viii. 369, . .An English Gent. . . 1751, x. 245 x. 270, Parker ■ - ■ ■ ■ — 1754, x. 563, Jamineaux 1758, xi. 236, Pademi 1760, xi. 521, 522, Stiles ■ ■ ■ xi. 522, Mackinlay 1765, xii. 417, Hamilton ■ 1767, xii. 494, Same — and other volcanoes in the neighbourhood, remarks on, xii. 592, Same — heat of the ground on, xiii. 93, Howard — eruption of 1779* xiv. 6l3, Hamilton — state of, after the eruption of 1784, xvi. 131, .. . Same — eruption of 1794, xvii. 492, Same Vibration, on the motion of a tense string, vi 14, . . Taylor Vievar, Rev. A., of an explosion in the air, viii. 383 Vieussen, Raymond, biographical notice of, iii. 210, Note — on the structure of the brain, ibid. — chemical experiments on human blood, iv. 283, 503 — on the structure of the ear, iv. 448 Villette, M., form and efficacy of his burning glass, i. 34 ; compared with those of Maginus and Septalius, i. 35 j of another larger, iii. 67 — effects of his burning glass, vi. 405, Harris & Desaguliers Vinadio, on the hot baths of, xi. 495, Bruni Vince, Rev. S., on progressive and rotatory motion, xiv. 726 — on the sums of infinite series, xv. 309, 638 — on motion as affected by friction, xv. 6*54 — method of rinding fluents by continuation, xvi. 150 — on the precession of the equinoxes, xvi. 303 — of investigating infinite series, xvii. 78 — on the fundamental property of the lever, xvii. 348 — of the motion and resist, of fluids, xvii. 466 5 xviii. 248 — an unusual refraction of the air, xviii. 436 Vincent, Nathaniel, on Dr. Papin's hydraulic engine, iii.239 Vinegar, method of making in France, i. 47 1 — of the four thieves, origin of the appellation, x. 573, Note Vines, to train over the roof of a house, ii. 6*0, .... Templer Vipers, different manner of brooding from snakes, i. 49 — experiments on the poison of, i. 411, Charasj reply to, 544, Redi — observations on the poison of, i. 58, Redi j erroneous opinions corrected, ibid, Note — on the poison of, i. 654, Bourdelot — experiments to ascertain the seat of the poison, ii. 8, Piatt — poison of, and several antidotes, iii. 653, Mayerne — some observations on, vi. 6*43, Sprengal — remedy used by the catchers for their bite, viii. 84, Burton — experiments on persons bitten by, ibid, Mortimer 5 fur- ther experiments, viii. 107, Atwell — plants efficacious in curing the bites of, viii. 87, . . . Note — efficacy of olive-oil, in curing the bite of, viii. 124, Wil- liams 5 viii. 26*7, Dufay — cure of the bite by sallad-oil, viii. 265, Vater — process of slipping off their skins, ix. 351, Mortimer — description of the coluber cerastes, xii. 355, Ellis Virginia, method of propagating the mulberry tree at, i. 66 -L- advantage of building ships at, ii. 6*0 — natural history, &c, of, ii. 301, Glover — account of a voyage to, iii. 544, 588, 639, Clayton — observations on some insects in, iv. 565, Banister Virginia, answers to queries respecting, viii. 328, . . Clayton Viscera, see Bowels. Vision, remarks on, deducing that the choroides is the prin- cipal organ of, i. 243, Marriotte ; reply to, by M. Pec- quet, 245 ; Marriotte's reply, 443 — new theory of, ii. 540, 6l 1, Briggs — controversy of Marriotte and Perrault on, ii. 644 — two cases of extraordinary vision, iii. 33, 99, • • • • Brigga — case of, affected by the jaundice, iii. 652, Dale — use, by myopes, of telescopes without eye-glasses, vi. 424 Desaguliers — of a person who could not distinguish colours, xiv. 143, Huddart — another similar case, xiv. 394, Whisson — as affected by the size of the optic pencil, experts, on, xvi. 165, Herschel — effect of the different refrangibility of light on it, xvi. 595 Maskelyne — observations on, xvii. 318, Young xvii. 403, Hosack — on the causes of double vision, xviii. 77, Home — power of natural vision compared with that by teles- copes to penetrate into space, xviii. 580, .... Herschel — see Eye, Sight. Visme, Stephen, de, earthquake at Macao, 1 767, xii. 60/ — of a species of monkey without tails, xii. 608 — Chinese method of heating rooms, xiii. 95 Vitriol, method of extracting from the Liege mineral, i. 17 — observations on, by a F. R. S-, ii. 133 ; continued, ibid. — oil of, augmentation in weight on exposure to air, iii. 11, Gould — origin of the white, and fig. of its crystals, iv. 427, Lister — manufacture of, in Bareith, ix. 69 1, Mounsey Vitrum antimonii ceratum, on the effects of, x. 207, Geoffroy Vitulus marinus, see Phoca. Vitus's dance, curt- d by electricity, xiv. 476, . . Fothergill Viviani, Vincent, biograp. account of, iii. 609, v. 137,Notes Viviparous, of viviparous flies, i. 600, iii. 47; Lister, ib.,Note Voight, Dr., chemical controversy with Kunckel, iii. 1 25 Volcano, eruption at Sorea, iv. 13, Witserv — burning mountains of the Molucco isles, 163, .... Same — at sea near Santerini, producing an island, v. 446, Bourgignon- — remarks on various, in Italy, xii. 593, Hamilton — of a volcanic hill near Inverness, xiv. 179* West — traces of, on the banks of the Rhine, xiv. 276, Hamilton — descr. of Morne Garou, at St. Vincent, xv. 634, Anderson — see jEtna, Vesuvius. Voluntaries, see Music. Volta, A., to render sensible weak electricity, xv. 263 — account of some of Galvani's experiments, xvii. 285 — electricity excited by contact of conduct, subst., xviii. 744 Vomit, of the black vomit of S. America, ix. 66 1, Watson Vomiting medicines, practice of, v. 399y Cockburn Vorticella, see Polypus (animal). Vortices, impossibility of the Cartesian, viii. 424, Sigorgne Vossius, Isaac, biographical account of, i. 1 16, Note — origin of the Nile and other rivers, i. 117 — inscription on a pillar dug at Rome, iii. 331 Voyages and travels, directions for seamen on, i. 50, 153, Rooke — from England to the Caribbees, i. 1 73, Stubbes Spain to Mexico, i. 292 — to the East Indies, i. 375, Sraithson — from Venice through Greece to Smyrna, ii. 284, Vernon Aleppo to Palmyra, iv. 33, Halifax - iv. 49, Merchants- 110 WAL INDEX. WAR Voyages, to Chusan in China, iv. 693, Cunninghame — from Cairo to the desart of Sinai, xii. 278, . .Montagu — to Hudson's Bay, xiii. 21, Wales Judda and Mocha, xiii. 287, Newland Voye, M. de la, of worms eating stones and mortar, i. 120 Vullyamy, B., of obtaining an overflowing well, xviii. 184 Vultures, descrip. of the vultur serpentarius, xiii. 93, Edwards W Wadd, chemical experiments on the black wadd [ochra fri- abilis nigro-fusca], xv. 409, Wedgwood Waddel, John, effects of lightning on the compass, ix. 652 Wagtail [calendula], from Hudson's Bay, xiii. 341, Forster Waite, Nich., incombustible cloth from China, iii. 178 Wales, on the nat. hist, of, v. 6*76', 6'77, 693, vi. 19,73,Lhwyd Wales, Wm., biographical account of, xii. 682, .... Note — transit of Venus, 1769, at Hudson's Bay, ibid — magnetic variation at Hudson's Bay, xii. 684 — a voyage to, and residence at, Hudson's Bay, xiii. 22 — meteorolog. observ. at Hudson's Bay, 1768, 1769, xiii. 32 — solar eclipse, June 1778, London, xiv. 460 — on the roots of affected equations, xiv. 139 Walker, — experiments and observations on sound, iv. 338 Walker, Adam, description of Dunmore Cavern, xiii. 36*8 Walker, John, account of the Hartsell Spa waters, xi. 87 — irruption of Solway moss, Dec. 1772, xiii. 203 Walker, Rich., prod, of artific. cold, xvi. 502, 579; xvii.560 — congelation of quicksilver in England, xvi. 579 Wall, — ?.i. d., phosphoric quality of amber, diamonds, gumlac, v. 408 Wall, J., m. d., biographical account of, ix. 369, .... Note — use of musk in convulsions, ix. 89 — use of Peruvian bark in the small pox, ix. 369 — essay on the Malvern waters, x. 673 — efficacy of the Malvern waters, xi. 68 — efficacy of oil as a vermifuge, xi. 307 Wallace, James, m. d., account of New Caledonia, iv. 487 — - of a hairy stone cut from the bladder, iv. 524 Waller, Rich., descrip. of the flying glow worm, iii. 109 — catalogue of simple and mixed colours, iii. 274 — spawn of frogs, production of tadpoles, iii. 456 — dissection of a paroquet, iii. 652 — two deaf per-ons who understood by the motion of the lips, v . 379 — anatomy of the wood-pecker, of its tongue, vi. 264 Wallis, John, d. d., biographical account of, i. 59, Note — account of an earthquake near Oxford, i. 59 — observations on the barometer, i. 60 — an accident by thunder and lightning, i. 74 — hypothesis of the flux and reflux of the sea, i. 89; reply to animadversions on it, i. 101 j Childrey's remarks on it, 5l6; Wallis's reply, 520 — idea of a universal principle of attraction, i. 102, Note — criticism on Vossius de Motu Marium et Venlorum : and on Gassendus de iEstu Maris, i. 105 — animadversions on Hobbes, i. 107, 6ll, 623 — inquiries concerning tides, i. 112 — annual tides of England various, i. 238 Wallis — account of Mercator's Logarithmotechnia, i. 273 ' — on the general laws of motion, i. 307 — observations on the baroscope and thermoscope, i. 4l6 — of teaching the deaf and dumb, i. #6'4 ; instance of a person so taught, i. 468 — on the Physica Nova of Leibnitz, i. 6l8 — answer to Hobbes' Lux Mathematica, ii. 11 — on the cener of gravity, ii. 12 — cause of mercurial suspension in a tube, ii. 44 — observations on a remarkable frost, ii. 56 US 98 Wallis, John, n. d., on veins in plants, ii. 74 — invention of a right line equal to a curve, ii. — on diagonal divisions, ii. 189 — on the trembling of consonant strings, ii. 380 — of an unusual meteor, ii. 389 — on the antiquity of Indian numerals, ii. 677 — account of two curious old chimney-pieces, iii. — of the varying gravity of the atmosphere, iii. 162 — secants, and division of meridians on sea charts, iii. 224 — instance of the strength of memory, iii. 248 — of a stone voided by urine, iii. 249 — resistance of the air to motion, iii. 350 — on the size of the horizontal sun, iii. 369 — geometrical problem on the construction of the dome of the temple at Delos, iii. 479 — to observe the parallax of the fixed stars, iii. 562 — approximation on the extraction of surd roots, iv. I — on cycloidal spaces perfectly quadrable, iv. 39 — cure of a horse staked in the stomach, iv. 65 — the cycloid known as early as 1450, iv. 169 — product, of hail, thunder, and lightning, iv. 197, 212 — storm of thunder, &c. at Everdon, iv. 2J6 — division of the monochord, iv. 240 — explanation of the rubrics for Easter, iv. 273 — on the imperfections in an organ, iv. 287 — remarks on ancient music and its effects, iv. 305 — reply to Leibnitz' remarks on philosoph. pursuits, iv. 414 — on an alteration of the meridian line, affecting the de- clination of the needle and the pole's elevation, iv. 414 — disadvantage of adopting the Gregorian calendar, iv. 434 — on the quadrature of the lunula of Hippocrates, iv. 455 — ways of measuring curved figures, iv. 488 — whether man is by nature carnivorous, iv. 550, 556 — of an isthmus supposed to have formerly existed between Calais and Dover, iv. 618, 637 — on the bones of large animals found in England, iv. 637 — invention and improvements of the compass, iv. 639, 655 — on Halley's chart of magnetic variations, iv. 655 Wallis, Capt. , solar eclipse at George's Island, 1 767, xiii. 276 Wallot, J. W., transit of Mercury, 1782, at Paris, xv. 553 Walmesley, Chas., biographical account of, xi. 17, .. Note — precession of the equinoxes, and nutatiou of the earth's axis, xi. 19 — theory of the inequalities of the earth's motions, x. 31 j theory compared with observed phenomena, 37 — motion of a satellite dependant on the shape of its planet, xi. 295 — irregularities in the planetary motions, xi. 579 Walnuts, of a new sort of walnut-tree, iv. 603, Reneaume Walpole, Horace, biographical account of, x. 135, . . Note — his own case, of the stone cured by soap and lime water, x. 135, 269 — further particulars of his case, xi. 1 1 5, 122, .... Pringle xi. 1 17, Whytt Walsh, John, electric power of the torpedo, xiii. 469 — torpedoes found near the British coast, xiii. 570 Wanley, Humphry, on judging the age of mss. v. 227 Ward/John, biographical account of, vii. 381, Note — of the equuleus of the ancients, ibid — of ancient dates in Indian figures, via 32, 39 — of Weidler*9 dissertation on numeral figures, ix. 46 — Roman inscription at Silchester, ix. 86, 599 — two ancient dates in Arabian figures, ix. 107 — explanation of some antiquities, ix. 118 — description of the town of Silchester; a Romangold coin } an ancient Arabic date, ix. 599 — Roman inscription in the country of the Sabines, x. 1. — explanation of a Greek inscription, x. 63 WAT INDEX. WAT ill Ward, John, Roman altar and inscription at York, x. 316 — explanation of a Roman inscription at Bath, x. 419 — a Roman inscription in Yorkshire, x. 577 — - Roman inscriptions near Wroxeter, x. 6'06 at Bath, x. 626 •——-—— on two pieces of lead, xi. 17 — • account of the black assize at Oxford, xi. 26*3 Wargentin, Peter, biographical notice of, x. l65, .... Note — variation of the magnetic needle, ibid — transit of Venus, June 176*1, and other astronomical observations, at Stockholm, xi. 56*0 — same transit at various places in Sweden, xi. 56*1 — remarks on the same transit, xi. 695 — longitude by eclipses of Jupiter's satellites, xii. 352 — state of the weather at Stockholm, 1767-8, xii. 534 — transit of Venus 176.9, in Sweden, xii. 6*51 — occupations of at and y tauri, xiii. 6±6 — differ, of the longitude of-Paris and Greenwich, xiv. 131 Waring, Edward, biographical account of, xii. 19, . . Note — algebraical and geometrical problems, ibid — new properties in conic sections, xii. 124 — theorems on the ellipse and polygon, xii. 222 — problems concerning interpolations, xiv. 483 — resolution of algebraic equations, xiv. 487 — on the summation of series, xv. 586 — on infinite series, xvi 6*1, xvii. 43 — to find the values of algebraic quantities, xvi. 191 — on centripetal forces, xvi. 384 — properties of the sum of divisors, xvi. 407 — method of correspondent values, xvi. 563 — resolution of attractive powers, xvi 572 Waring, Rich. Hill, of plants indigenous in England, xiii.171 Wark, Rev. David, utility of furze for dam-heads, xi. 514 Warner, Joseph, tumour inside the bladder extracted, x. 32 — on the operation of the empyema, x. 244 — bone extracted with a stone from the bladder, x. 270 — successful operation of the empyema, x. 394 — exper. on the agaric of oak, in stopping bleedings, x.479 — effects of the agaric of oak, x. 546" — successful treatment of diseased knee-joints, x. 671 — aneurism of the principal artery of the thigh, xi. 157 — stones extracted by the lateral method, xi. 225 — case of empyema, xi. 372 — stones fixed in the urethra for 6 years, and afterwards successfully cut out, xi. 395 — a small foetus produced with a live child, xiii. 79 Warren, George, dissection of an ostrich, vii. 150 Warren, Sam., earthquake of 1756 in England, x. 703 Warrick, Christ., remarkable formation of a child, viii. 5S9 — improved method of tapping for ascites, ix. 5, 40 — success of injecting claret after tapping, x. 676 Wasps, on the sexes of, vii. 16, Derham — curious nests of clay in Pennsylvania, ix. 123, Bartram — great black wasp of Pennsylvania, ix. 6"99> Same — economy of a small sort, in England, x. 182, Harrison «— an American wasp's nest, x. 607, Mauduit — of the yellow wasp or Pennsylvania, xi 6S5, . . Bartram — of a singular species of, Jamaica, xii. 99> Felton Wasse, Rev. Mr., difference in height of the human body at morning and night, vii. 24 — effects of lightning, vii. 105 — an earthquake in Northamptonshire, Oct. 1731, viii. 98 Watches, description of his portable, ii 199, • • • Huygens — — ii. °03, .... Leibnitz — remarks by the editor of the p. t., on the invention of a spring to the balance, in reply to animadversions by Mr. Hook, ii. 237 Watches, on the times of vibration of the balance, xvii. 380, Atwood — for pendulum watches, see Longitude. Water, difference between Thames and other water in keeping at sea, i. 174, ii. 311 — difference in the quality of, at Jamaica and the Caymar Jsles, i. 175 — of the salt and fresh water at Bermudas, i. 206, Norwood — extraordinary eruption from a rock, iv. 322, RP. j r. 293, . . Thoresby — cause of the different tastes of, iv. 601, . . Leuwenhoek — peculiar quality of the water of a morass in Lincolnshire ix. 364, Stovin — see Sia-nater, Springs, SfC Waters, extraordinary agitation of at various places, Nov. 1, 1755, viz. at Portsmouth, x. 647, Robertson ' ■ in Sussex, &c, ibid, Webb at Cobham, x. 649, Adee Medhurst, ibid, Hodgson Cranbrook, ibid, Tempest _______ Tunbridge, ibid, Pringle ■ ■■ the Thames, x. 650, Mills ' ■ ■ Peerless Pool, ibid, Birch ■ - Rochford, x. 657, .... Tomlinson near Reading, ibid, Philips ibid, Blair — Oxfordshire, x. 652. Lord Parker Devon and Cornwall,ibid,Huxham coast of Cornwall, x. 653, Borlase Tophtz in Bohemia, x.655,Steplin the Hague, ibid, De Hondt ■ Haarlem and Rotterdam, ibid, Allamand Feb. 1, 1756, Dumfrieshire, x. 692, Kilpatrick Lake Ontario, x.695, Mrs.Belcher Nov. 1, 1755, Scotland and Hamburgh, x. 6*97, Pringle Dartmouth, xi. 1, . . Holdsworth the sea at Antigua, xi. 9, Affleck in Hert fords., xi. 16, Rutherforth — March 31, 176*1, Cornwall and elsewhere, xi.6l, Borlase Water (nat. and exper. philosophy) on the ascent and descent of bodies in, i. 76 — to estimate its weight, in water, i. 374, Boyle — to find the quantity of air in, i. 479> Same — cause of the swimming of a heavy body in a lighter men- struum in which it was dissolved, iii. 295, . . Molyneux — to determine its specific gravity, iii. 437, Boyle — of its pressure at great depths, iii. 444 — way to ascertain the degree of saltness, iii. 496, . . Boyle — of its pressure at great depths, iii. 585, Oliver — its weight compared with that of air, v. 288,. . Hauksbee — ascent in small tubes, in vacuo and in air, v. 289, Same — weight under different circumstances, v. 452, 470, Same — on its seeming spontaneous ascent, v. 464, Same — different densities at different temperatures, v. 469, Same — shape of its ascent between planes, v. 706, Taylor v. 707, vi. 40, Hauksbee — experts, on the electricity of, vii. 513, Gray — cause of intermitting springs, vii. 544, Atwell — on the heat of boiling water, ix. 13, Montesquieu — on the compressibility of, xi. 6*63, xii. 151,.... Canton — specific g avity of salt and fresh, xii. 207, . . • Wilkinson — to distil fre-^h from salt, xiii. 289, Newland — to separate fresh from salt by freezing, xiv. 48 . . Barker — variat. of the temperat. of boiling, xiv. 537, ^huck burgh — on the heat of the Gulph stream, xv. 1 15, .... Blagden — on the constituent parts of, xv. 555, 569) ........ Watt 112 W AT INDEX. WE A Water (nat. and exper. philosophy) to cool below the freez- ing point, xvi. 409, Blagden — experiments on the composition of, xvi. 419, 473, 5 IS, Priestley — theory of floating bodies, xvii. 682, xviii. 315,.. Atwood -r- see Hydraulics, Fluids. Waters, (mineral and medicinal) remarkable spring at Pader- born, i. 47 — three springs at Basil, ibid — rich salt springs in Germany, i. 48 — nature and efficacy of the Bath waters, i. 36*1, . . Glanvil — at Farrington, Dorsetshire, i. 420, Highmore — method of analyzing, ii. 577, Note — enquiries to ascertain the nature of, iii. 99> Petty — on an experimental history of, iii. 183 — of a hot spring in Jamaica, iv. 79, Beeston — a medicated spring in Glamorganshire, iv. 211, . . Aubry — vitriolic water at Eglingham, iv. 317, Cay — at St. Amand near Tournay, iv. 337, Geoffroy — St. George's bath near Landeck, v. 333, Ehm — at Canterbury, analysis and virtues of, v. 375, Moulins — examen of chalybeate waters, vi. 6l, Slare — at Westashton well, analysis of, viii. 522, Hanckewitz, — a purging spring at Dulwich, viii. 523, Marfyn — of the Fontaine deSalut, atBagneres, ix. 12, Montesquieu — strength of several purging waters, x. 48, Hales — of the Wicklow copper-springs, experts, on, x. 366, Bond ■i- enq. into the air in spa- water, xii . 235, xiii. 541, Brownrigg — salt purging waters of Pitkeathly, xiii. 272, Same — analysis of the water of the Mere Diss, xviii. 423,Hatchett — see Springs ; also, Amlwch, Bath, Bristol, Carlsbad, Castel-leod, Hammam-pharoan, Hartsell, Holt, Jessops well, Kilburn, Matlock, Pyrmont, Scarborough. Water (medicine) of cold water in fevers, vii. 353, Cyrillus — of a man who lived 1 8 years on, viii. 6l6, . . . . Campbell — effects of hot and cold, salt and fresh, on the powers of the body, xvii. 193, Currie Water (nat. hist.) eruption of a boiling spring, v. 680, Hopton — luminousness of, in the Indian seas, vi. 53, . . Bourzes — see Springs. Water-spout, see Spout. Water-clock, see Clepsydra. Wathen, Jon., operation for remedying an obstruction of the eustachian tube, x. 609 Watkins, Thomas, method of computing interest, vi. 97 Watson, H., of the lymphatics of the urethra, &c. xii. 667 — of the stomach of the gillaroo trout, xiii. 510 Watson, Richard, d. d., [Bp. of Llandaff ] of the solution of salts, xiii. 59 — effects of the cold in Feb. 1771, xiii. 130 — effect of painting the bulb of a thermometer, xiii. 370 — chemical experiments on lead ore, xiv. 447 — on the sulphur wells at Harrowgate, xvi. 83 Watson, Wm., m.d., biograph. account of, ix. 38,.. Note — case of part of the lungs coughed up, viii. 468 — hydatids voided per vaginam, viii. 494 — observ. on Sutton's ventilators, and on windsails, viii. 560 — on the seeds of mushrooms, viii. 721, ix. 41 — persons poisoned by boiled hemlock, ix. 38 — on mushrooms ; poisonous nature of fungi, ix. 41 — figure of the lycoperdon fornicatum, ix. 93 — large stone in a horse's stomach, ix. 101 — experiments and observations on electricity, ix. 151, 195, 408, 410. 440 — of Beccaria's book on articles emitting phosphoric light, ix. 209 — poisonous effects of the cenanthe crocata, ix. 256, xi. 31 1 Watson, Wm., m.d., to communicate electricity to non- electrics, ix. 308 — velocity of electricity, &c. ix. 440 — abstract of Brownrigg on making salt, ix. 518 — experts, to ascertain the velocity of electricity, ix. 553 — account of the black vomit of South America, ix. 66l John Tradescant's garden at Lambeth, ix. 668 — small-pox capable of infecting the foetus in utero, ix. 692 — on odours made to pervade glass by electricity, x. 13 — on the experiment, in eleciricity, of beatification, ibid — account of the [then] new metal platina, x. 97 — observations on the sex of plants, x. 176 — poisonous effects of henbane, x. 186 — account of Dr. Franklin's treatise on electricity, x. 189 — Bishcp of London's botanic garden at Fulham, x. 200 — account of the cinnamon tree, x. 217 — account of Bohadsch's treatise on electricity, x. 227 — experiments on electricity in vacuo, x. 233 — of Bianchini's book on medical electricity, x. 242 — rare plants unnoticed in Ray's Synopsis, x. 250 — account of Peyssonel's ms. treatise on coral, x. 257 — remarks on some vegetable balls, x. 280 — electrical experiments on thunder-clouds, x. 302 — on sweetening sea-water, x. 327 — comparison of thermometrical observ. in Siberia, x. 344 — account of Gmelin's Flora Sibirica, x. 351 — on the Abbe Nollet's letters on electricity, x. 372, xi. 580 — remarks on the vegetable byssus, x. 425 — on the sex of holly, x. 487 — death of Professor Richman by electricity, x. 525 — large calculus found in a mare, x. 541 — an enquiry into the species of the agaric, x. 546 — Mr. Tull's method of castrating fish, x. 554 — species of plant of the French agaric, x. 563 — Mr. Pulteney's account of Leicestershire plants, xi. 45 — ace. of Springsfeld's treat, on the Carlsbad waters, xi. 57 — plants of the genus lichen, xi. 246 — some extraordinary effects of convulsions, xi. 272 — observations on the lyncurium of the ancients, xi. 419 — of the cicuta recommended for medicinal uses, xi. 530 — account of experts, by Professor Braun on artificial cold, xi. 544 — method of protecting ships from lightning, xi. 660 — of an influenza and dysentery in London, 1762, xi. 667 — effects of electricity applied to a tetanus, xi. 679 — description of the vegetable fly, xii. 15 — of the American armadilla, xii. 99 — an apparatus for protecting buildings, and particularly powder-mills, from lightning, xii. 127 — dissection of a person dead of asthma, xii. 145 — account of the severe cold of Feb. 1767, xii. 474 • — of the plant arachidna of North Carolina, very productive of oil, xii. 665 Watson, W., Jun., m.d., account of the blue shark, xiv. 423 Watson, Rob., M. d., date of the death of, x. 686, . . Note — remarks on a piece of music by Philodemus found at Herculaneum, x. 685; an epigram of Philodemus, 686 Watt, James, component parts of water, and dephlogisticated air, xv. 555, 569 — a test liquor for acids and alkalies, xv. 605 Wax, produced from insects in China, x. 388, D'Incarville — see Chermes. Weather, on the doctrine of vapours, rain, &c. iii. 157, 210, Garden — reply to Garden's doctrine, iii. 162, Wall's — effect of its changes on mercury, iii. 304, Halley — plan of a register of the weather, v. 206, Locke — comparison of, at Zurich and Upminster, v. 497, Derham WEN INDEX. WIL 113 Weather, on the making of observations on it, vi. 67 5,Jurin — cause of a dry and a wet summer, viii. 447 — plan and instruments for a diary, ix. 34, Pickering — remarks on weather and thermometers, ix. 6l7, Miles — phenomena attributed to electricity, x. 591* Eeles — plan for keeping journals, xiii. 6l6, Horsley — general state of, at Bengal, xiii. 632, Barker ■ ■ - in the windward islands, xiv. 521, Cazaud — extraordinary drought at Sumatra, and an attendant phe- nomenon, xv. 1 27, Marsden — on the influence of cold weather on the health of the in- habitants of London, xviii. 1, Heberden — see Barometer, Thermometer, Meteorological Observations, Rain, Frost, fyc. Weather cord, see Hygrometer. Weaver's larum, see Larum. Weaving, mach. acting without an artificer, ii. 439, Gennes — Le Blon's method of weaving tapestry, vii. 477, Mortimer Webb, Phil. Cart,, an inverted rainbow on the grass, x. 201 — agitation of the waters, Sussex, x. 6*47 Wedge, powerful effect of wedges, xi. 136, .... Robertson Wedgwood, Josiah, biographical account of, xv. 27$, Note — thermom. for high degrees of heat, xv. 278, 571, xvi. 136 — chemical experts, with Derbyshire black wadd, xv. 409 — analysis of a mineral from New South Wales, xvi. 667 — production of light by heat and attrition, xvii. 128, 215 Weesel, from Hudson's Bay [mustela nivalis], xiii. 327, Forster Weidler, John Fred., biographical account of, vii. 384,Note — lunar eclipse at Wittemberg, vii. 364} viii. 96, 147 — astronomical observations, 1728, 1729, vii. 384 — solar eclipse at Wittem., vii. 427, 660j viii. 176, 306,359 — aurorae boreales at Wittemberg, vii. 644 — of caterpillars. &c. at Wittemberg, vii. 645 — meteorological observations at Wittemberg, viii. 68, 76 — parhelia seen at Wittemberg, viii. 137 — transit of Mercury over the sun, 1736, viii. 149 — observations on an anthelium, viii. 358 - — occultation of Aldebaran by the moon, 1738, viii. 358 Weighelius, philosophical instruments invented by, i. 6l7 Weight, pressure of, on moving bodies, x. 558, .... Hee — of bodies, diminished by heat, xvi. 13, Fordyce — see Gravity. Weights, of Paris compared with English, vi. 494, Desaguliers Weights and measures, comparison of ancient and modern, iii. 241 , Bernard — - of the Jews, iii. 276, Cumberland — analogy of the English, viii. 432, Barlow — comparison of the English and French, viii. 604, . . R. S. — Standard of English, viii. 698, Same ■ ix. 637, Reynardson — of England, prior to Henry VII., xiii. 582, Norris — endeav. to ascertain a standard of, xviii. 300, Shuckburgh Wells, of a well taking fire at a candle, i. 169, .... Shirley — of an ebbing and flowing well nearTorbay, iii. 585, Oliver — description of a burning well at Brosely, ix.305,. . Mason — of a burning well in the East Indies, xi. 600, .... Wood — description of the King's wells at Sheerness, Landguard Fort, and Harwich, xv. 46l, Page — temperature of, in Jamaica, xvi. 277, ...... . Hunter — to obtain an overflowing well, xviii. 184, .... Vullyamy — see Waters {Mineral and Medicinal;) Damps. Wells, Wm., Chas, m. v., cause of muscular contraction in galvanic experiments, xvii. 548 — observs. and experts, on the colour of blood, xviii. 228 Wen, see Tumour. Wendland, Caspar, case of 38 stones in a bladder, ii. 115 Wendlebury, wood petrified without water, found at, i. 38 Wendlingen, J. lunar eclipse at Malritus, 1757, xi. 245 Weredale, of a subterraneous cavern at, ix. 254, . . Durant West, Thos., of a volcanic hill near Inverness, xiv. 179 Weymarn, Mons., of an earthquake in Siberia 1761, xii. 3 Whale, of the Bermudas, description of, i. 6, 283 — species of, on the coast of New England, i. 46 — microscopical observations on the flesh and eye of, v. 155, Leuwenhoek — on the seminal vessels, blood, &c. of, v. 672, Same — of New England, nat. history of, vii. 78, .... Dudley — machine for throwing the harpoon at, x. 251, . . Bond — description of rhe spermaceti whale, xv.395, Schwaediawer — structure and economy of whales, xvi. 306, .... Hunter — some particulars in the anatomy of, xvii. 673, Abernethy — see Cachalot. Whale fishery, at the Bermudas, account of, i. 6, 46, 106 Wharton, Thos., m. d., biographical notice of, i. 322, Note Wheat, experiments on the culture of, xii. 554, .... Miller Wheels, advantage of high wheels for carriages, iii. 1 14 — best construction of water-wheels, xii. 446, .... Mallet Wheeler, Rev., chronometer on an inclined plane, iii. 58 Wheler, Granville, solar eclipse, 1733, vii 6l4 — repulsive force of electrical bodies, viii. 306 — his electrical experiments before the r.s., viii. 313 — remarks on Mr. Gray's circular electrical experts, viii. 3l6 — rotation of glass tubes before a fire, ix. 114 Whirlwind, see Wind. Whiston, G., four parhelia, observed at Kensington, vii. 186 Whiston, Rev. Wm., biographical account of, vi. 532, Note — parhelia, and an inverted rainbow, ibid. White, Chas., remark, operation on a fractured arm, xi. 475 — complete luxation of the thigh bone, xi. 482 — removal of the os humeri without loss of the arm's mo- tion, xii. 597 White, Rev. Gilbert, account of the house martin, xiii. 529 — of the house swallow, swift, and sand martin, xiii. 645 White, Taylor, difference between the cinnamon of Ceylon and Malabar, xi. 3 1 3 White, Wm., m. d., effects of effluvia on the air, xiv. 322 — bills of mortality of York, xv. 177 Whitfield, Anne, of a storm of thunder and lightning, xi. 392 Whitehurst, John, biographical account of, xii. 440, Note — extreme cold at Derby, Jan. 1767, ibid. — description of a machine for raising water, xiii. 645 — experiments on the weight of ignited bodies, xiv. 112 Whytt, Robert, m. d., biographical account of, xi. 117, Note — earthquake at Glasgow, 1755, x. 687 — a shower of ashes at sea, ibid — efficacy of soap and lime water in the stone, xi. 117, xi. 160 — comparative efficacy of Carlsbad waters, lime-water, and soap, in curing the stone, xi. l6l — cases of the efficacy of blisters in coughs, xi. 220 Wilbraham, Thomas, case of hydrophobia, x. 245 Wildbore, Rev. C, biographical account of, xvi. 740. Note — on spherical motion, xvi. 740 Wilcox, Joseph, discovery of some subterraneous apartments in Italy, with paintings, &c, xi. 706 Wilkins, John, d. d , biographical memoir of, i. 254, Note Wilkins, W , a star-like light on the dark part of the moon, xvii. 450 Wilkinson, John, m. d., experiments on the buoyancy of cork, xii. 204 Willard, Joseph, longitude of Cambridge, New Eng., xv. 1 57 Williams, Rev. A., remarkable storm of thunder, &c, xiii. 93 Williams, J. Lloyd, description of the Benares observatory, xvii. 291 — method of making ice at Benares, xvii. 294, 305 P ZAC INDEX. zuc fear, on the solar and lunar, x. 33, . . Earl of Macclesfield — division by the Fantee nation, xv. 27, Dobson — table of years of the Christian Era corresponding with those of the Mahometan, xvi. 514, Marsden — on the Hindoo civil year, xvii. 250, Cavendish Yew tree, of the farinaTcecundans of, ix. 243, .... Badcock Yonge, J., internal use of cantharides, iv. 696 — of a plum-stone in the bowels 30 years, iv. 715 — cases of hair-balls extracted from the uterus, &c. v. 347 — of a bunch of hair voided by urine, v. 518 — several solid bodies voided by urine, v. 520 — an unusual blackness of the face, v. 521 — - several extra-uterine foetuses, v. 522 — dropsical distention of the gall-bladder, v. 66*7 — instance of the menses continuing to 70 years of age, vi. 55 York, on the population and salubrity of, xv. 177, . . White — its latitude and longitude determined, xvi. 145, . . Pigott Yorkshire, observs. on the nat. hist, of, vi. 45, . . Richardson Younes Ebn, translation of a passage in, xiv. 133, . . Costard Young, Charles, reduction of a luxated thigh bone, xi. 496 Young, Thomas, m. d. observations of vision, xvii. 318 — experiments and inquiries on sound and light, xviii. 604 Zach, Francis de, astronomical observations, xv. 60 1 Zangari, Countess, narrative of her death, ix. 138, Bianchini Zannoni, J. A. Rizzi, astronomical observations at Naples and Sicily, xii. 554 Zanotti, Eust., meteoric lights observed Dec. 1737, viii. 459 — orbid of the comet of 1739, viii. 515 — transit of Venus over the sun, 1761, xi. 597 Zetland, see Shetland. Zeus Luna, description of, x. 79 Mortimer Zinc, use of an amalgam of, for electrical excitation, xiv. 446, , Higgins Zirchnitz, account of the lake of, i. 409, ii. "70,. . Brown iii. 411, Valvasor Zodiac, opinion of the ancients on the obliquity of, iii. 75, Bernard — ancient carvings of, in India, xiii. 321, Call Zoophyta, descr. of the actinia calendula, viii. 717, Hughes — gorgonia verrucosa, ix. 198,. . Miles — figures of, xi. 537, Baster — description of the isis asteria, xi. 591, Ellis — on the animal nature of, xii. 458, Same — nature of the gorgonia, xiii. 720, Same — chemical experiments on, xviii. 706, Hatchett — seeAlcyonium, Corallines, Gorgonia, Pennafula, Tubularia, Polypus, Sertularia. Zucchius, probably the inventor of the reflecting telescope, xviii. 230, Note ERRATA. Vol. I. Page 233, line 3, for fig. 7 read fig. 1. 711, line 2 from bottom, after ABCD add (fig. 5, plate 15.) Vol. II. Page 199, line 15, for fig. l read fig. 18. Vol. III. Page 45, line 20, for plate 2 read plate 1. 59, last line, for G. read C. 1 19, line 28, for thee read thea. 452, table 2, line 2, for 25. 2. 4. read 25. 2. 3. and in line 4, for 1944 read 1644. ■ ' 453, table I, line 1, page 1, for 2.44 read 2. 44&. and in line 7, for 2.33£ read 2.33. - table 2, line 12, for 2.44. read 2.54. - 455, table 1, line 2, for 6.55. read i.55$, and in line 3, for 27- 7- 20. read 23. 7- 20. Vol. VIII. In the Contents, page 4, col. 2, line 32, and page 10, col. 2, line 3 1 , for Committee of the R. «. read Geo. Graham. Vol. IX. Vol. X. Page 244, line 30, for tittle read little. — 56l, 562, 563, for d. M. read U. R. Page 70, line 10, read plate I. 106, line 11, read fig. 16. 381, line 3, for A read a. — 676, line 22, for for read from. Vol. X II. Page 356, line 16, for 94 read 5£. Vol. XIII. In the Contents, page iii. line 14, dele Chro- nology. Vol. XVII. Page 284, note, for subiategra read subintegra. See also a few Errata at the ends, or on the pages containing references to the plates, of Vol. I. II. IV. V. VI. VII X. XIV. XV. XVI. XVII. but some of these have been cor- rected in a large portion of the impression while going through the press. FINIS. C. »ixl R. Baldwin, Printer?, Wew Bridge . 3$. %c . JIBCIW&IH VWS* IwaFflCire^ /w. 10 MMair S fuJAulicd by c't-R Baldwin, of 5few 3ridx]c Strcet,lcndon,i8off . * • 'H Vol. XVJ1L . fhilos. Trans . fl AM. 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